High sensitive micro sized magnetometer

Abstract

The magnetometers possess detector part with a magnetic wire sensitive to magnetic field consisting of a domain structure of the surface domain with circular spin alignment and core domain with longitudinal spin alignment and micro coil surrounding its magnetic wire to pick up the change of longitudinal magnetizing caused by spin rotation in surface domain with circular spin alignment called as GSR effect excited by pulse with frequency of 0.5 GHz to 4 GHz. Peak coil voltage is detected by a circuit characterized with pulse generator, GSR element, Buffer circuit, sample holding circuit, amplifier circuit and means to invert it to external magnetic field. The induced coil voltage caused by parasitic coil capacitance and wiring loop is vanished by combination coil of right and left turn coil. The magnetometers can provide lower noise, wide measuring range with a small size detector part and is applied to smartphones, wearable computer and so on.

Claims

1. A high sensitive micro sized magnetometer, comprising: a detector part with a magnetic wire sensitive to magnetic field and a coil surrounding the magnetic wire, the detector part being configured to pick up a change of longitudinal magnetizing caused by spin rotation in a surface domain with circular spin alignment; a pulse generator circuit configured to supply a pulse current to the magnetic wire; a buffer circuit and a sample holding circuit, the sample holding circuit comprising an electronic switch synchronized with a pulse current timing for switching the electronic switch on and off, and a holding capacitance to charge a peak coil voltage by switching off the electronic switch; and an amplifier circuit configured to amplify the voltage of the holding capacitance and to invert a value of the peak coil voltage to a strength of an external magnetic field, wherein the magnetometer, which has the magnetic wire consisting of a domain structure of a surface domain with circular spin alignment and a core domain with longitudinal spin alignment to provide an anisotropy field of the magnetic wire of under 10 G of and the coil with the inner diameter of under 25 m and the coil pitch of under 10 m excited by the pulse with the frequency of from 0.5 GHz to 4 GHZ and the current strength to make over 1.5 times larger circular magnetic field than the anisotropy field of the magnetic wire, and wherein the peak coil voltage is detected under a condition to secure the skin depth to make smaller than the thickness of the surface domain to detect only a GSR effect, which means high speed spin rotation with GHz frequency induced in the surface domain, and the peak coil voltage is converted to the external magnetic field using the sine equation (1)
Vs=Vo.Math.sin(H/2Hm)(1) where Vs is a coil voltage, Vo is a constant, Hm is a magnetic field to give a maximum coil voltage and H is an external magnetic field.

2. The high sensitive micro sized magnetometer according to claim 1, wherein the peak coil voltage is detected by combination coils connected by four types coil of R.sup.+, R.sup., L.sup.+, L.sup. expressed as (R.sup.++R.sup.), (L.sup.++L.sup.), (R.sup.+L.sup.+), (R.sup.L.sup.), (R.sup.++R.sup.) (L.sup.++L.sup.), R.sup.+L.sup.+)+(R.sup.L.sup.) where R or L indicate right or left turning coil, respectively, and signs of + or indicate the direction of the current same to plus or minus direction of the external magnetic field, respectively, to give addition of all signal voltages corresponding to the external magnetic field and vanish all induced coil voltages caused by parasitic coil capacitance.

3. The high sensitive micro sized magnetometer according to claim 1, wherein a combination coil expressed as (R.sup.+L.sup.+) , (R.sup.L.sup.) consists of one wire surrounding a right turn coil and a left turn coil and the wiring to connect two electrodes and four coil terminals such that a pulse electrode connects to a pulse terminal of a coil through a minus coil terminal, a pulse coil terminal of another coil, the minus coil terminal finally to the minus coil electrode which has a grand separation between coil terminals and electrodes to form a wiring loop which can give addition of all signal voltages corresponding to the external magnetic field and vanish all induced coil voltages induced in the wiring loop.

4. The high sensitive micro sized magnetometer according to claim 1, wherein a combination coil expressed as (R.sup.++R.sup.)(L.sup.++L.sup.), (R.sup.+L.sup.+)+(R.sup.L.sup.)consists of two wires surrounding a right turn coil and a left turn coil and wiring to connect two electrodes and eight coil terminals such that a pulse electrode connects to a pulse terminal of a coil subsequently connecting a minus coil terminal to a pulse coil terminal of another coil and a pulse coil to a minus coil terminal of a next coil in turn to the minus coil electrode which has two grand separations positioned between coil terminals and electrodes to form two loops which can give addition of all signal voltages corresponding to the external magnetic field and vanish all induced coil voltages induced in the wiring loop.

5. The high sensitive micro sized magnetometer according to claim 1, wherein a calculation program or operation circuit is configured to calculate an actual coil voltage by subtracting an induced coil voltage measured at the external magnetic field of zero from a measured coil voltage Vm.

6. The high sensitive micro sized magnetometer according to claim 1, wherein an effect of temperature with respect to the peak coil voltage is calibrated using a temperature sensor and a calibration program.

7. The high sensitive micro sized magnetometer according to claim 1, wherein the magnetic wire is an amorphous or nanostructure wire of CoFeSiB alloy consisting of the core domain with longitudinal spin alignment and the surface domain with circular spin alignment formed by: (i) a tension annealing to make a circular anisotropy; or (ii) a pulse annealing to vanish a magnetic hysteresis using the pulse current with a strong current strength.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1A and 1B are schematic view of the magnetizing curve of the amorphous magnetic wire.

(2) FIG. 1A is the schematic view of the magnetizing curve for the longitudinal external magnetic field.

(3) FIG. 1B is the schematic view of the relationship between the coil voltage and the longitudinal external magnetic field.

(4) FIG. 2 is a schematic view of the change of the magnetic domains of the amorphous wire by increase of the external magnetic field. a) H=0, b) H=Hk/2, c) H=Hk, d)H>Hm

(5) FIGS. 3A and 3B are schematic view of the effect of the external magnetic field on the coil voltage for Example 1.

(6) FIG. 3A is the schematic view of the relationship between the external magnetic field and the coil voltage.

(7) FIG. 3B is the schematic view of the relationship between the external magnetic field and the converted coil voltage.

(8) FIG. 4. is a schematic view of the effect of the pulse frequency on the coil voltage for Example 1.

(9) FIG. 5. is a schematic top view of GSR element introduced as Example 1.

(10) FIGS. 6A, 6B, and 6C are schematic cross section view of GSR element introduced as Example 1.

(11) FIG. 6A is the schematic top view of GSR element.

(12) FIG. 6B is the schematic cross section view of the coil of GSR element.

(13) FIG. 6C is the schematic cross section view of the electrode of GSR element.

(14) FIG. 7 is a schematic top view of GSR element introduced as Example 2.

(15) FIG. 8 is a schematic top view of GSR element introduced as Example 3.

(16) FIG. 9 is a schematic top view of GSR element introduced as Example 4.

(17) FIG. 10 is a schematic of the circuit applied to examples.

DESCRIPTION OF EMBODIMENTS

(18) The optimum embodiments of the present invention on GSR sensor based on spin rotation effect caused by the pulse current with GHz frequency is explained as bellow. The first embodiment of the present invention is applied mainly to electronics compass detecting the earth magnetic field of 0.5 G used for smartphone or wearable computer.

(19) The embodiment is expected to provide the excellent performance and small size with the length of under 0.4 mm and width of under 0.2 mm.

(20) The sensor performance requested for electronics compass are noise of under 1 mG, measuring range of over 20 G, sensitivity of under 1 mG/bit, measurement interval of under 1 msec,and current consumption of about 0.2 mA. The above performance is far better than that of conventional MI sensor used for electronics compass which has 2 mG, 12 G, 1.5 mG/bit, 5 msec, 0.4 mA respectively.

(21) GSR sensor consists of a GSR element and a circuit detecting the coil voltage. The coil voltage measured is converted to the external magnetic field using the equation (2). GSR element consists of wires, pickup coils, electrodes and wirings on the substrate. The circuit consists of a pulse generator, a GSR element, a buffer circuit, a sample holding circuit, a detection timing modification circuit and a programming amplifier.

(22) The magnetic wire used is an amorphous wire of CoFeSiB alloy with the diameter of 3 m to 10 m coated with the glass of under 1 m thickness. The amorphous structure is desirable but the nanocrystal structure is available. The magnetic properties are characterized by the anisotropy field of under 10 G, the magneto-striction of zero or minus small value, the permeability of 1000 to 100,000 and the specific resistivity of over 80 cm.

(23) The wire is needed to be insulated against the coil by coating the wire with glass or resign. Another way to hold the insulation is to inset insulating material into the gap between the wire and the coil but this way is apt to produce the bigger gap between coil and wire than that to use coated wire. So this way in not favorable.

(24) The high permeability of the magnetic wire which corresponds to low anisotropy field can improve the sensitivity of GSR sensor proportional to the coil voltage but makes the measuring range to be narrow.

(25) The micro coil used for the invention can solve the tradeoff problem between the sensitivity and measuring range. The micro coil is produced with narrow coil pith of under 10 m improved from 30 m of coil pitch of MI sensor. It can increase coil numbers regardless of short length of the wire and can improve the sensitivity.

(26) When the wire of the micro coil prepares the length of under 0.20 mm, the output can provide the measuring range of over 30 G. On the contrary, the plating coil type MI sensor has the wire length of 0.6 mm to make the measuring range of 12 G.

(27) The wire has a particular structure which consists of the core domain with longitudinal spin alignment and the surface domain with circular spin alignment. This structure is formed by longitudinal anisotropy field Ku and circular anisotropy field K produced by tension annealing. The thickness of the surface domain is proportional to K. The more thickness, the less sensitivity. So that it is desirable to prepare that of 0.1 m to 1 m.

(28) For pulse current causes spin rotation of the surface domain massively, strength of pulse current is needed over 50 mA to produce the circular magnetic field H of more than 1.5 Hm around the wire. The strength of circular magnetic field H is enlarged according to anisotropy field K of the wire but an unreasonable big pulse current should not be used because it causes heating and increase of the current consumption. In the present embodiment, the suitable range of the pulse current and circular magnetic field are 100 mA to 200 mA and 40 G to 80 G respectively.

(29) The effect of the frequency on the coil voltage is characterized as below.

(30) At the frequency of 0.5 GHz to 1 GHz the coil voltage increases with the frequency proportional to f.sup.1/2 and then at 1 GHz to 2 GHz it has peak voltage. But at 2 GHz to 4 GHz, it decreases gradually and at over 4 GHz it drops drastically because the precession appears or strong eddy current produce heating on the surface. It is concluded that the pulse frequency applied are suitable within 0.5 GHz to 4 GHz.

(31) The optimum range of frequency is from 1 GHz to 3 GHz. It makes skin depth of 0.05 m to 0.5 m. Thickness of the surface domain controlled by anisotropy field K should be enlarged than the skin depth. The pulse width of more than 1 nsec is needed. The range are suitable with over 5 nsec to 10 nsec which can avoid the interference between both coil wave voltages, that is, rising pulse and falling pulse.

(32) The coil voltage is caused by circular magnetic field of over 60 G produced by pulse current passing through the wire. The circular magnetic field is reversal proportional to the diameter D of the wire. For decreasing the pulse current, it is desirable the diameter should become smaller as far as possible. The diameter should be at least under 20 m for forming the surface domain with circular spin alignment. The diameter of over 20 m cannot form the specified structure. Moreover making the micro coil, the small diameter is better in production. But the coil voltage is proportional to the diameter so that too small diameter is not good. It is resulted that the diameter is suitable for 5 m to 12 m.

(33) The wire length influences in the coil voltage and measuring range Hm which are restricted by tradeoff relationship. Wider measuring range can be obtained by shorter wire. Higher coil voltage can be obtained by longer wire. So the suitable range of the wire length is recommended to 0.1 mm to 0.5 mm for electronics compass application. The invention can provide the noise of under 1 mG and measuring range of over 30 G under the wire length of 0.2 mm and micro coil with coil pitch of 5 m.

(34) The micro coil with the coil pitch of under 10 m is produced using 3 dimensional photolithography. The process is to produce at first a groove with width of under 20 m and depth of 7 m on the Si substrate, secondary a lower side coil pattern on the groove. Thirdly the wire coated by insulating material is inserted into the groove following fixed using adhesive and finally a upper side coil pattern is made on the wire. Subsequently the terminal on the wire is prepared by stripping off the coating material and it is connected to wire electrodes by conductive wire produced using sputtering equipment.

(35) The smaller in the coil pitch, the better for increasing coil turn numbers. But considering the difficulty to produce the ultra-micro coil, the suitable range of the coil pitch must be from 1 m to 6 m.

(36) The GSR element design is important to vanish the induced coil voltage which increases with increase of the pulse frequency. The main sources of the induced coil voltages are the parasitic capacitance of the coil and the wiring loop formed by combination coil wiring.

(37) As shown in FIG. 8 the combination coil of the present embodiment has two wires binding right turn coil each other passing the pulse current through two wires with opposite directions. This combination coil is expressed as R.sup.++R.sup..

(38) The signal voltage proportional to the external magnetic field is added because of same sig. But the induced coil voltage caused by the parasitic capacitance is cancelled because of opposite sign.

(39) As for wiring loop design, two loops are formed by two grade separation which detects the magnetic field with same sign produced by the pulse current. But two voltages is added with opposite current directions of the loop each other. If the loops have same area with a line symmetry, the induced coil voltages in two loops are cancelled to vanish. But it is hard to produce two loops with perfect equal area using this combination coil wiring design.

(40) FIG. 5 shows another combination coil of the present embodiment has two wire binding both of a right turn coil and a left turn coil each other passing the pulse through two wires with opposite direction. This combination coil is expressed as (R.sup.++R.sup.)(L.sup.++L.sup.).sup.. The above discussion makes clear that both combination coils expressed as (R.sup.++R.sup.) and (L.sup.++L.sup.) provide addition for signal voltage proportional to the external magnetic field because of same sign and subtraction for the induced coil voltage by the parasitic capacitance of opposite sign. Subtracting the coil voltage of (L.sup.++L.sup.) from that of (R.sup.++R.sup.), the combination coil voltage as (R.sup.++R.sup.)(L.sup.++L.sup.) gives addition of four signal coil voltages.

(41) As for wiring loop design, two loops are formed by two grade separation which detects the magnetic field with same sign produced by the pulse current. But two induced voltages are added with opposite current directions of the loop each other. If the loops have same area with a line symmetry, the induced coil voltages in two loops are cancelled to vanish. Moreover this combination coil wiring design is easy to make two loops with equal area.

(42) The distortion from symmetrical structures on producing the coils and the wiring mentioned above make residence Vc of the induced coil voltage. In this case, it is desirable to obtain the true coil voltage Vs by subtracting the induced coil voltage Ye measured at Hex=0 from the measured coil voltage Vm using calculation program or operation circuit. When residence Vc of the induced coil voltage Vc measured at Hex=0 is not negligible compared to the maximum output voltage .Math.E max of operation amplifier, the sensitivity of GSR sensor decrease dependent on the residence Vc. Because effective voltage of .Math.E max decreases to EmaxVc. As example, when .Math.E max=1V, Vc=0.5V, at the worst case, the output of GSR sensor decreases from 1V to 0.5V which means the sensitivity makes decreases of 50%.

(43) The other reason why it is important to vanish or decrease the induced coil voltage is explained. The coil voltage is induced a little later than the induced coil voltage because the induced coil voltage is induced with synchronization to the circular magnetic field but the coil voltage is induced with synchronization to spin rotation moving behind the circular magnetic field because eddy current makes braking force.

(44) The peak coil voltage is detected at the timing when the external magnetic field gives the most sensitive effect to the coil voltage. Even if the temperature affects circuit to shift the detection timing, the influence in the coil voltage is small because the top of the peak is flat against time deviation. GSR sensor with combination coil to vanish the induced coil voltage has good temperature dependence on origin drift of 0.02 mG per degree corrected by using the temperature measured by the temperature sensor equipped inside of the sensor circuit.

(45) However if the induced coil voltage wave remains, its detection timing is delayed from the peak point of the induced coil voltage and it is detected at the sharp slope which makes bad temperature dependence. So that it is desirable to vanish the induced coil voltage.

(46) The present embodiment provide the performance mentioned above under the numbers of the coil turn numbers of over 20 and the resistance of over 10 however it can provide suitable performance within the coil turn numbers of 40 to 100 and the coil resistance of 100 to 400 . The wire resistance of 4 to 40 is suitable.

(47) The outputs of the present embodiments are measured by the GSR sensor circuit having a buffer circuit 55 shown in FIG. 10. It is resulted that the designated output voltages are obtained. As for connection with GSR elements and ASIC (integrated circuit) of GSR sensor, electrodes of elements are soldered to electrodes of ASIC directly.

(48) The circuit 5 shown in FIG. 10 consists of a pulse generator 51, a GSR element 52, a buffer circuit 55, a sample holding circuit 56, a programming amplifier 59 and an AD converter and a digital circuit for signal processing.

(49) The pulse generator 51 generates the pulse current with the pulse frequency of 2 GHz passing through the wire of GSR element 52 and the coil of the element detects the coil wave voltage transferring to the buffer circuit 55 following the sample holding circuit 56 to hold the peak voltage in the capacitance 58 which corresponds to the external magnetic field.

(50) The buffer circuit 55 suppress the pulse current through the coil to nearly zero so that IR drop voltage becomes negligible level even if the resistance is large.

(51) The peak voltage is inverted to digital signal within 8 bit to 16 bit by an analog digital converter ADC transferring to a digital circuit where it converts the value of the external magnetic field and output to outside processors. The digital circuit equips a memory to hold the measured data, calibrate program and initial numerical values.

(52) The embodiments provide the excellent performance and small size with the length of under 0.4 mm and width of under 0.4 mm. The performance achieved are noise of 0.05 mG to 1 mG, measuring range of 20 G to 60 G, sensitivity of under 1 mG/bit, measurement interval of 1 msec, and consumption current of about 0.2 mA. The above performance is better than that of conventional MI sensor used for electronics compass which are 2 mG, 12 G, 1.5 mG/bit, 5 msec, and 0.4 mA respectively.

(53) The present embodiments used for the electronics compass can improve the performance index S of over 100 times better than that of conventional MI sensor used in the commercial electronics compass.

(54) The second embodiment of the present invention is applied to pT sensor detecting the bio magnetism of 1 pT level used for Magnetocardiography or magnetoencephalogram.

(55) The second embodiments prepare same design and basic parameter same to the first embodiments. However the wire length is 1 mm to 5 mm to increase the coil voltage and the sensitivity of the present embodiments. The size of the elements are length of 1 mm to 5 mm, width of 0.6 mm to 1.8 mm. The coil turn numbers are increased by 300 to 2000 to make detection of the ultra-small bio magnetism possible. The structure of the element consists of single or plural combination coil with combination of right turn coil and left turn coil. It is desirable to control the resistance of the combination coil from 500 to 2 k and the wire resistance from 20 to 40 k.

(56) The embodiments provide the excellent performance characterized by noise of 1 pT to 100 pT, measuring range of under 30 mT, sensitivity of 0.1 pT/bit to 1 pT/bit, measurement interval of 1 msec to 10 msec, the linearity of under 1% and current consumption of about 10 mA. The above performance is better than that of conventional MI sensor used for electronics compass which are 2 mG, 12 G, 1.5 mG/bit, 5 msec, 0.4 mA respectively. The present embodiments used for the bio magnetism sensor can provide the noise of 1 pT 1000 times better than that of 1 nT (where nT =10 G) achieved by a commercial nT sensor based on MI sensor.

(57) The third embodiment of the present invention is applied to industrial use such as home appliance, automotive, Robot and so on detecting the signal magnetic field of 10 G to 300 G emitted by magnets attached into the artificial system. This embodiments are characterized by the wide measuring range of over 100 G given by the design with the wire length of under 0.1 mm, the coil pitch of 2 m to 6 m, and the coil turn numbers of 15 to 50. The detail performance of the embodiments such as noise, measuring range, measuring cycle, power consumption sensor size and so on are designed with the main factors of GSR sensor optimized according to applications.

(58) As shown in FIG. 8 the combination coil of the present embodiment has two wire binding right turn coil each other passing the pulse through two wires with opposite direction. The combination coil is expressed as R.sup.++R.sup.. The signal voltage proportional to the external magnetic field is added because of same sign and the induced coil voltage by the parasitic capacitance is cancelled because of opposite sign.

(59) As for wiring loop design, two loops are formed by two grade separations which detect the magnetic field with same sign produced by the pulse current. But two induced voltages are added with opposite current directions of the loop each other. If the loops have same area with a line symmetry, the induced coil voltages in two loops are cancelled to vanish.

(60) The fourth embodiment of the present invention is applied to electronics compass detecting the earth magnetic field of 0.5 mG used for a catheter, a gastro scope and an endoscope characterized by ultra-small size and high sensitivity which are achieved by the design with the wire diameter of under 5 m, the wire length of under 0.02 mm, the coil pitch of under 1 m, and the coil turn numbers of 10 to 20.

(61) Every type of combination coil designs can be used for this embodiment, but one wire type might be suitable to make element size small because of the simple structure.

(62) The combination coil wiring expressed as (R.sup.+L.sup.+) or (R.sup.L.sup.) is explained using the Example 4 shown in FIG. 9 drawing the top view.

(63) The wire on the GSR element substrate has two terminals of plus terminal and minus terminal which are connected by the plus wire electrode and minus wire electrode respectively. The current direction of plus is defined to be same to the external magnetic field direction of plus which is base direction. Each coil has two terminals of plus and minus and similarly a combination coil has two terminals of plus and minus. The wiring of the combination coil expressed as (R.sup.+L.sup.+) is made as bellow.

(64) Plus coil electrode is connected to plus terminal of combination coil which means plus terminal of R.sup.+ coil following minus terminal of R.sup.+ coil is connected to plus terminal of L.sup.+subsequently minus terminal of L.sup.+ is connected to minus coil electrode. It is necessary that two connecting wires of plus coil electrode joining plus combination coil terminal and minus coil electrode joining minus combination coil terminal must prepare grade separation.

(65) The combination coil of (R.sup.+L.sup.+) which makes subtraction of both coil voltage can output the additional coil voltage of right turn coil and left turn coil, dependent on the external magnetic field, because both coil voltages have opposite sign. It also can cancel both induced coil voltages dependent on parasitic capacitance of both coils produced by plus current because both induced coil voltages have same sign.

(66) The wiring loop on the element substrate is formed by a grade separation and divided to cross section by the wire. Both side crosses can catch flux with same strength but opposite sign to achieve zero summation of flux passing through the wiring loop so that the induced coil voltage by wiring loop is vanished.

(67) By the way, similar wiring design is applied can be applied to the combination coil expressed as (R.sup.L.sup.).

(68) The fifth embodiment of the present invention is applied to magnetic imaging applications detecting the earth magnetic field of 0.5 mG used for a magnetic microscope, a magnetic camera, a paper money detection and so on. This embodiments are characterized by ultra-high measuring speed of 10 MHz to 100 MGz and low noise of under 1 mG as well as its small size. The embodiments equip the arrayed GSR elements controlled by high speed switch.

(69) As mentioned above using five embodiments, the present sensors are used for many applications by making a lot of designs according to the applications which request very different specifications such as the noise of from 100 nT to 1 pT, measuring range of 0.1 mT to 30 mT, measuring speed of 20 Hz to 100 MHz and elements length of 0.02 mm to 2 mm. One of advantages of the present invention is to make possible many designs according to many applications.

EXAMPLES

Example 1

(70) The first example according to the first embodiment of the present invention is applied to electronics compass detecting the earth magnetic field of 0.5 mG used for smartphone or wearable computer. The example provide the excellent performance and the small size with the length of 0.2 mm and width of 0.2 mm. The performance are noise of 0.2 mG, measuring range of 50 G, sensitivity of 0.2 mG/bit, measurement interval of 1 msec, and current consumption of 0.1 mA. The above performance is better than that of conventional MI sensor used for electronics compass which are 2 mG, 12 G, 1.5 mG/bit, 5 msec, 0.4 mA respectively. GSR sensor consists of the GSR element and the circuit detecting the coil voltage and measures the external magnetic field converted from the coil voltage using the equation (1).

(71) The GSR element consists of the wire, pickup coil, electrodes and wiring on the substrate. The circuit consists of a pulse generator, an element, a buffer circuit, a sample holding circuit, a detect timing modification circuit and a programming amplifier.

(72) The top view of GSR element used in the first example is shown in FIG. 5. It is a combination coil expressed as (R.sup.++R.sup.)(L.sup.++L.sup.) which has two wire 21, 22 respectively with right turn coil 21R, 22R and left turn coil 21L, 22L passing pulse current of opposite sign with each other. The detail structure of the element 2 is explained by the top view and cross section view of the single element shown in FIG. 6.

(73) The magnetic wire used is an amorphous wire of CoFeSiB alloy with the diameter of 10 m coated with the glass of 1 m thickness. The amorphous structure is desirable but the nanocrystal structure is available. The magnetic properties are characterized by the anisotropy field of under 5 G, the magneto-striction of 10.sup.6, the permeability of 10,000 and the specific resistivity of 100 cm.

(74) The wire is insulated against the coil by coating the wire with glass. The wire has a particular domain structure which consists of the core domain with longitudinal spin alignment and the surface domain with circular spin alignment. This structure is formed by longitudinal anisotropy field Ku and circular anisotropy field K produced by tension annealing.

(75) The thickness of the surface domain increases to result the decrease of the sensitivity because the thickness is proportional to K. So that it is desirable for under 1 m. The strength of pulse current is 200 mA to produce the circular magnetic field H of 60 G on the wire surface so that it causes spin rotation of the surface domain massively. The width of the pulse is 5 msec to make pulse annealing to the wire for vanishing the core domain as well as magnetic hysteresis by means that the 90 degree magnetic wall moves from surface to the center to produce vortex structure.

(76) The frequency of 2 GHz is used to make the skin depth of 0.12 m which is below the thickness of the surface core of about 0.5 m. The amorphous wire has the diameter of 10 m and the length of 0.2 mm which makes the measuring range Hm of 40 G.

(77) The coil turn numbers is 48 turns and the coil pitch is 5 m.

(78) The cross section of the coil 43 shown in FIG. 6 consists of the magnetic wire 42 with glass coating positioned on the coil center fixed by adhesive resign 47, Si substrate 4 with the groove 41, the lower side coil 431 wiring on the groove 41, the upper side coil 432 wiring on the magnetic wire 42 and the step joint part 433 with both coil wirings.

(79) The wire 42 is fixed inside the groove 41 by the adhesive resign 47 and the insulation with the coil and the wire is kept by the glass coating on the wire. The wire terminals 44 which are formed by removal of the glass are connected to the wire electrodes 45 with joint part 46 produced by metal vaporing.

(80) As for the wire wiring of the combination coil shown in FIG. 5, the pulse current pass through the wires with opposite direction with each other by the connection from the plus wire electrode 23 through wire connection part 25, plus terminal 21+ of left hand wire 21, minus terminal 21 of it, plus terminal 22+ of right hand wire 22, minus terminal 22 of it to the grand wire electrode 24. As for the coil wiring, the coil voltage is added by the wiring connection from plus coil electrode 26 through plus terminal 261 of L.sup.22L, minus terminal 262 of L.sup.22L, plus terminal 263 of L.sup.+21L, minus terminal 264 of L.sup.+21L, plus terminal 265 of R.sup.22R, minus terminal 266 of R.sup.22R, plus terminal 267 of R.sup.+21R, minus terminal 268 of R.sup.++21R to grand coil electrode 27 with grade separation 269 of two connecting wires of plus electrode 26 joining plus combination coil terminal and grand coil electrode 27 joining minus combination coil terminal.

(81) This combination coil is expressed as (R.sup.++R.sup.)(L.sup.++L.sup.). The above discussion makes clear that both combination coils expressed as (R.sup.++R.sup.) and (L.sup.++L.sup.) provide addition for signal voltage proportional to the external magnetic field because of same sign and subtraction for the induced coil voltage by the parasitic capacitance of opposite sign. Subtracting the coil voltage of (L.sup.++L.sup.) from that of (R.sup.++R.sup.), the combination coil voltage as (R.sup.++R.sup.)(L.sup.++L.sup.) gives addition of four signal coil voltages.

(82) As for wiring loop design, two loops are formed by two grade separation 269 and coil terminals 261 to 268 which detect the magnetic field with same sign produced by the pulse current. But two voltages are added with opposite current directions of the loop each other. If the loops have same area with a symmetry, the induced coil voltages in two loops are cancelled to vanish.

(83) The distortion from symmetrical structures on producing the coils and the wiring mentioned above makes the difference between coil voltages which results in the residence Vc of the induced coil voltage. The true coil voltage Vs is obtained by subtracting the induced coil voltage Vc measured at Hex=0 from the measured coil voltage Vm using calculation program or operation circuit.

(84) The present Example 1 provides the performance mentioned above under the numbers of the coil turn numbers of 48 turns and the resistance of 220 . The output of the present Example 1 is measured by the GSR sensor circuit having a buffer circuit shown in FIG. 10. It is resulted that the designated output voltage is obtained. As for connection with an elements and ASIC (integrated circuit) of GSR sensor electrodes of elements are soldered to electrodes of ASIC directly.

(85) The circuit 5 shown in FIG. 10 consists of pulse generator 51, GSR element 52, buffer circuit 55, a sample holding circuit 56, programming amplifier 59 and AD converter and digital circuit for signal processing. The pulse generator 51 generates the pulse current with the pulse frequency of 1 GHz passing through the wire of GSR element 52 and the pickup coil of the element detects the coil wave voltage transferring to the buffer circuit 55 following the sample holding circuit 56 to hold the peak voltage which corresponds to the external magnetic field.

(86) The buffer circuit suppress the pulse current through the wire to nearly zero so that IR drop voltage becomes negligible level even if the resistance is large. The peak voltage is inverted to digital signal within 14 bit by an analog digital converter (ADC) transferring to a digital circuit where it is converted to the value of the external magnetic field and is output to outside processors. The digital circuit equips a memory to hold the measured data, calibrate program and initial numerical values.

(87) The Example 1 provides the excellent performance and small size with the length of 0.2 mm and width of 0.2 mm. The performance are noise of 0.2 mG, measuring range of 50 G,sensitivity of 0.2 mG/bit, measurement interval of 1 msec, and consumption current of 0.1 mA. The above performance is better than that of conventional MI sensor used for electronics compass which are 2 mG, 12 G, 1.6 mG/bit, 5 msec, 0.4 mA respectively. It is concluded that the performance index of the Example 1 is achieved 160 better than that of conventional MI sensor produced by considering tradeoff relationship between sensor properties.

(88) The second Example 2 according to the second embodiment of the present invention is applied to pT sensor detecting the bio magnetism of 100 pT level with the noise of 1 pT used for Magneto cardiograph or magneto encephalogram. FIG. 7 shows a top view of the element 3 of the Example 2. That equips four wires binding both right turn coil 31R,32R,33R,34R and left turn coil 31L,32L,33L,34L per each wire passing the pulse through four wires 31,32,33,34 with opposite direction. The combination coil is expressed as (R.sup.++R.sup.)(L.sup.++L.sup.)+(R.sup.++R.sup.)(L.sup.++L.sup.). The pulse current pass through from the pulse wire electrode 35+ through four wires to the grand wire electrode 35G. As for the coil wiring, the coil voltage is added by the wiring connection from plus coil electrode 36+ through 16 coil terminals and 4 grand separations 37 to grand coil electrode 36G.

(89) The present combination coil expressed as 2(R.sup.++R.sup.)2(L.sup.++L.sup.) provide addition for signal voltage proportional to the external magnetic field and subtraction for the induced coil voltage by the parasitic capacitance 54 of opposite sign.

(90) The wiring loop design with four loops is formed by four grade separations 37 which detects the magnetic field with same sign produced by the pulse current. All of loops make same induced voltage due to same area with opposite current directions of the loop each other. As the wiring connected four loops, it is resulted that the induced coil voltages in the wiring is cancelled to vanish.

(91) Comparing with the Example 1, the wire length of the Example 2 is lengthened from 0.2 mm to 2 mm. The coil turn numbers are increased from 48 turns to 1000 turns, that is, 20 times bigger. The magnetic wire used has excellent magnetic property with the anisotropy of 1.5 G from 5 G. The measuring range is decreased from 40 G to 2 G, that is, 20 times smaller. The resistance of the combination coil is 5 k and the wire resistance is 40 .

(92) The above optimum design increases the coil voltage accompanied with increase of the sensitivity and decrease of the noise of 2 pT from 20nT to make detection of the ultra-small bio magnetism of under 100 pT possible at room temperature. The Example 2 for bio magnetism detector provides excellent performance of the noise of 2 pT, measuring range of 2 G, sensitivity of 1 pT/bit, linearity of under 1%, temperature origin drift of 0.2 pT/degree and current consumption of under 10 mA.

Example 3

(93) The third Example 3 according to the third embodiment of the present invention is applied to industrial use such as home appliance, automotive, Robot and so on detecting the signal magnetic field of 200 G emitted by magnets attached into the artificial system.

(94) As shown in FIG. 8 the combination coil 2 of the present embodiment which has two wires 21,22 binding left turn coil 1L,22L each other passing the pulse from pulse wire electrode 23 through two wires with opposite direction to grand wire electrode 24 and coil wiring connected from pulse coil electrode 26 through coil terminals 261,262,263,264 to grand coil electrode27 expressed as L.sup.++L.sup..

(95) The signal voltage proportional to the external magnetic field is added because of same sign and the induced coil voltage by the parasitic capacitance is cancelled because of opposite sign.

(96) As for wiring loop design, two loops are formed by two grade separation 269 which detects the magnetic field with same sign produced by the pulse current. But two voltages are added with opposite current directions of the loop each other. If the loops have same area with a line symmetry, the induced coil voltages in two loops are cancelled to vanish.

(97) This embodiments are characterized by the wide measuring range of +200 G given by the design with the wire length of 0.08 mm, the coil pitch of 2 m,and the coil turn numbers of 48 turns keeping other design factors such as the pulse frequency, the magnetic wire, and the electronics circuit to be same to the Example 1.

(98) The performance provides the noise of 1 mG, the measuring range of 200 G, the linearity of under 1%, the temperature original drift of 0.1 mG/degree C and the current consumption of 0.1 mA at the measuring cycle of 200 Hz. The Example 3 is suitable for industrial applications such as home appliance, automotive, Robot, electric power sensor and so on.

Example 4

(99) The fourth Example 4 according to the fourth embodiment of the present invention is applied to electronics compass used for medical devices used in human body such as a catheter, a gastro scope and an endoscope. It is characterized by ultra-small element size with the wire diameter of 2 m and the wire length of 40 m in addition to the magnetic wire with the anisotropy field of 1.5 G and the diameter of 2 m, the coil pitch of 1 m and the coil turn numbers of 32 turns which gives high sensitivity to detecting the earth magnetic field of 0.5 G.

(100) The Example 4 has the combination coil wiring expressed as (R.sup.+L.sup.+) shown in FIG. 9 drawing the top view. It has one wire 21 binding right turn coil 21R and left turn coil 21L passing the pulse through one wires with one direction is expressed as R.sup.+L.sup.+. The coil wiring 21 is connected from the plus coil electrode 23 through four terminals 261, 262, 263, 264 and a grand separation 269 to grand coil electrode 24.

(101) The wiring loop on the substrate 2 is formed by a grade separation 269 and is divided to two sections by the wire passing through pulse current. Both side sections can prepare flux with same strength but opposite sin to achieve zero summation of flux passing through the wiring loop so that the induced coil voltage by wiring loop is vanished.

(102) The performance provides the noise of 2 mG, the measuring range of 50 G, the linearity of 1%, the temperature original drift of under 0.02 mG/degree C. and the current consumption of 0.05 mA at the measuring cycle of 200 Hz.

(103) The Example 3 is suitable for electronics compass applications used for medical devices used in human body such as a catheter, a gastro scope and an endoscope.

Example 5

(104) The fifth Example 5 according to the fifth embodiment of the present invention is applied to magnetic imaging applications used for a magnetic microscope, a magnetic camera, a paper money detection and so on characterized by ultra-high measuring speed of 20 MHz.

(105) The Example 5 equips the arrayed GSR elements derived with pulse interval of 50 nsec and each element is detected by high speed switch to output by the measuring cycle of 20 MHz.

INDUSTRIAL APPLICABILITY

(106) The present invention is based on GHz spin rotation phenomena in the surface domain of the amorphous magnetic wire called as GSR effect. It comes true to detect the magnetic field of pT, high sensitivity, very high speed measuring of 20 MHz, and low current consumption with very small size. It is expected for a lot of applications such as electronics compass, magnetic gyro, bio magnetism sensor, micro sensor in medical device used in human body, magnetic camera, and industrial sensor.

(107) TABLE-US-00001 [Reference Signs List] 10: BH curve 11: Coil voltage vs the external magnetic field 12: Longitudinal cross section of the wire 13: Cross section of the wire 14: Surface domain 15: Core domain 16: Left oriented spin 17: Right oriented spin 18: Spin orientation in the surface domain 19: Spin orientation in the core domain 2: GSR elements for Examples of 1, 2 and 4 21: Left side wire 21+: Plus wire terminal of left side wire 21: Grand wire terminal of left side wire 22: Right side wire 22+: Plus wire terminal of right side wire 22: Grand wire terminal of right side wire 21L: Left turn coil of left side wire 21R: Right turn coil of left side wire 22L: Left turn coil of right side wire 22R: Right turn coil of right side wire 23: Plus wire electrode 24: Grand wire electrode 25: Wire connection part 26: Plus coil electrode 27: Grand coil electrode 261 to 268: Coil terminal 269: Grand separation 28: Groove on the substrate 3: GSR element of Example 2 31: First wire 32: Second wire 33: Third wire 34: Fourth wire 31R, 32R, 33R, 34R: Right turn coil 31L, 32L, 33L, 34L: Left turn coil 35+: Plus wire electrode 35G: Grand wire electrode 351, 352, 353: Wire connection part 36+: Plus coil electrode 36G: Grand coil electrode 37: Grand separation 4: Substrate of combination coil 41: Groove on the substrate 42: Magnetic wire 43: Coil 431: Lower side coil wiring 432: Upper side coil wiring 433: Step of joint part 44: Wire terminal 45: Wire electrode 46: Joint part 47: Resign 5: Electronics circuit 51: Pulse generator 52: GSR element 53: Input side circuit 54: Parasitic coil capacitance 55: Buffer circuit 56: Sample hold circuit 57: Electronics switch 58: Sample holding capacitance 59: Amplifier