METHOD FOR THE RECONFIGURATION OF A VORTEX DENSITY IN A RARE EARTH MANGANATE, A NON-VOLATILE IMPEDANCE SWITCH AND USE THEREOF

Abstract

A method for reconfiguration of a vortex density in a rare earth manganate, to a non-volatile impedance switch having reconfigurable impedance, and to the use thereof as micro-inductance is disclosed. A unique voltage-time profile is applied between a first and a second electrically conductive contact attached to the rare earth manganate, such that the rare earth manganate passes through an ordering temperature in a region of an electric field forming between the two electrically conductive contacts during a cooling process during and after application of the voltage pulse or the voltage ramp, and the vortex density is thus influenced and adjusted locally in the region of the electric field forming between the two electrically conductive contacts.

Claims

1. A method for reconfiguring a vortex density in a rare earth manganate comprising: applying a one-off voltage-time profile between a first and a second electrically conductive contact of the rare earth manganate attached to the rare earth manganate; allowing a cooling process so that the rare earth manganate goes through an ordering temperature in a region of an electric field established between the two electrically conductive contacts during and after application of the one-off voltage-time profile; and wherein the vortex density is thus influenced and set locally in the region of the electric field established between the two electrically conductive contacts.

2. The method for reconfiguring a vortex density in a rare earth manganate as claimed in claim 1, wherein the voltage-time profile is a voltage impulse or a voltage ramp.

3. The method for reconfiguring a vortex density as claimed in claim 1, wherein a temperature gradient of greater than 1 K/min, preferably greater than 10 K/min, more preferably greater than 100 K/min, is generated for reconfiguring the vortex density with a resulting impedance having a dominant inductive reactance.

4. The method for reconfiguring a vortex density as claimed in claim 1, wherein a temperature gradient of less than 100 K/min, preferably less than 10 K/min, more preferably less than 1 K/min, is generated for reconfiguring the vortex density with a resulting impedance having a dominant capacitive reactance.

5. A nonvolatile impedance switch having a vortex density reconfigured by the method as claimed in claim 1, comprising a layer sequence consisting of at least one layer composed of a rare earth manganate and a first contact which is arranged on one side of the rare earth manganate and also a second contact which is arranged on the side opposite the first contact or on the same side as the first contact and also insulating structures for heat removal controlled over time and for setting of a temperature gradient while an ordering temperature of the rare earth manganate is gone through.

6. The nonvolatile impedance switch as claimed in claim 5, wherein at least one of the two contacts has a structured configuration.

7. The nonvolatile impedance switch as claimed in claim 5, wherein the rare earth manganate is the material hexagonal YMnO.sub.3.

8. The nonvolatile impedance switch as claimed in claim 5, wherein the thickness of the layer sequence is greater than 5 nm and less than 5000 nm.

9. The nonvolatile impedance switch as claimed in claim 5, wherein the first contact and/or second contact has an area of from 10.sup.1 to 10.sup.5 μm.sup.2, preferably an area of from 10.sup.1 to 10.sup.3 μm.sup.2.

10. The use of the nonvolatile impedance switch as claimed in claim 5 wherein the impedance switch is incorporated as discrete component in an electronic circuit for adapting a phase shift.

11. The nonvolatile impedance switch as claimed in claim 5 wherein the impedance switch is configured as tunable filter.

12. The nonvolatile impedance switch as claimed in claim 5 wherein the impedance switch is configured as two-pin component for discrete passive components.

13. The nonvolatile impedance switch as claimed in claim 5 wherein the impedance switch is configured as flip chip for integration into circuits for energy-efficient voltage transformers.

14. The method for reconfiguring a vortex density as claimed in claim 2, wherein a temperature gradient of greater than 1 K/min, preferably greater than 10 K/min, more preferably greater than 100 K/min, is generated for reconfiguring the vortex density with a resulting impedance having a dominant inductive reactance.

15. The method for reconfiguring a vortex density as claimed in claim 3, wherein a temperature gradient of less than 100 K/min, preferably less than 10 K/min, more preferably less than 1 K/min, is generated for reconfiguring the vortex density with a resulting impedance having a dominant capacitive reactance.

16. The nonvolatile impedance switch as claimed in claim 6, wherein the rare earth manganate is the material hexagonal YMnO.sub.3.

17. The nonvolatile impedance switch as claimed in claim 7, wherein the thickness of the layer sequence is greater than 5 nm and less than 5000 nm.

18. The nonvolatile impedance switch as claimed in claim 8, wherein the first contact and/or second contact has an area of from 10.sup.1 to 10.sup.5 μm.sup.2, preferably an area of from 10.sup.1 to 10.sup.3 μm.sup.2.

19. The nonvolatile impedance switch as claimed in claim 9 wherein the impedance switch is configured as tunable filter.

20. The nonvolatile impedance switch as claimed in claim 9 wherein the impedance switch is configured as two-pin component for discrete passive components or as flip chip for integration into circuits for energy-efficient voltage transformers.

Description

[0032] The drawings show:

[0033] FIG. 1 nonvolatile impedance switch of the invention with charged domain walls (and insulation structures) —unconfigured (a) with two electrodes on the front side, (b) an electrode on the front side and an electrode on the rear side, (c) hexagonal domain structure with vortex in the center;

[0034] FIG. 2 a) nonvolatile impedance switch of the invention with charged domain walls and low vortex density and dominant capacitive reactance, b) nonvolatile impedance switch of the invention with charged domain walls and high vortex density and dominant inductive reactance;

[0035] FIG. 3 frequency-dependent behavior of the configured impedance switch;

[0036] FIG. 4 confirmation of the nonvolatility of a) the reactance of the impedance switch and b) the temperature stability thereof;

[0037] FIG. 5 modeling of the measured complex impedance Z with dominant inductive reactance;

[0038] FIG. 6 modeling of the measured complex impedance Z with dominant capacitive reactance;

[0039] FIG. 7 comparison between modeling and measurement results for the quality factor and the resonant frequency for material in the low-resistance state (LRS) having a thickness d=110 nm and connected external capacitances of different values;

[0040] FIG. 8 comparison between modeling and measurement results for the quality factor and the resonant frequency for material in the low-resistance state (LRS) having a thickness d=160 nm and connected external capacitances of different sizes;

[0041] FIG. 9 comparison between modeling and measurement results for the quality factor and the resonant frequency for material in the low-resistance state (LRS) having a thickness d=190 nm and connected external capacitances of different sizes;

[0042] FIG. 10 comparison between modeling and measurement results for the quality factor and the resonant frequency for material in the high-resistance state (HRS) having a thickness d=110 nm and connected external inductances of different sizes;

[0043] FIG. 11 comparison between modeling and measurement results for the quality factor and the resonant frequency for material in the high-resistance state (HRS) having a thickness d=160 nm and connected external inductances of different sizes;

[0044] FIG. 12 comparison between modeling and measurement results for the quality factor and the resonant frequency for material in the high-resistance state (HRS) having a thickness d=190 nm and connected external inductances of different sizes;

[0045] FIG. 13 voltage-time profiles: a) short voltage pulse, b) short voltage ramp, c) long voltage pulse, d) long voltage ramp.

[0046] FIG. 1 shows the schematic structure of the nonvolatile impedance switch 1 of the invention composed of a rare earth manganate 4 with charged domain walls 5 and insulation structures 8. In one possible embodiment, an electrically conductive rear side contact 2 has been deposited on the layer sequence on a substrate layer 6 by means of thin film technology. The total thickness of the layer sequence in tunable electrical resonators and filters should be greater than 5 nm and less than 5000 nm. Finally, an electrically conductive front side contact 3 has been applied to the opposite side of the rear side contact 2. The second contact 3 can also be applied to the same side as the rear side contact 2 on the layer sequence 4. At least one of the two contacts 2, 3, i.e. either the front side contact 3 and/or the rear side contact 2, is structured. The layer sequence 4 comprises at least one layer which has charged domain walls 5. This layer is a rare earth manganate, for example YMnO3. In the production process, the material is typically heated to a substrate temperature below the ferroelectric ordering temperature, resulting in the vortex 7 density being established spontaneously.

[0047] FIG. 2a shows the nonvolatile impedance switch 1 of the invention with charged domain walls 5 having a lower vortex 7 density and dominant capacitive reactance. As a result of the application of a short voltage pulse of high amplitude to the contacted layer sequence, charged domain walls 5 having a high vortex 7 density are formed.

[0048] FIG. 2b shows the nonvolatile impedance switch of the invention with charged domain walls 5 of high density and dominant inductive reactance. As a result of application of a long voltage pulse of low amplitude to the contacted layer sequence, charged domain walls having a low vortex 7 density are formed.

[0049] FIG. 3 shows the frequency-dependent behavior of the configured impedance switch 1 in a frequency range from 1 kHz to 40 MHz. After application of the threshold voltage USET, the resistance of the rare earth manganate thin layer switches from high (HRS: high-resistance state) to low (LRS: low-resistance state). After application of the threshold voltage URESET, the resistance of the rare earth manganate thin layer switches from low (LRS) to high (HRS).

[0050] FIGS. 4a and 4b show that the impedance of the impedance switch 1 of the invention is independent of time and temperature, i.e. the impedance behavior can be set in a nonvolatile manner.

[0051] FIG. 5a depicts an equivalent circuit of the material having charged domain walls 5 for modeling the measured complex impedance Z with dominant inductive reactance. Essentially, modeling is done by an inductance Lp in series with a resistance Rp and, parallel thereto, two (Rp, Cp) pairs (Rp1, Cp1 and Rp2, Cp2). The impedance and the quality factor as depicted in FIGS. 5b to 5d were modeled by the equivalent circuit shown in FIG. 5a. The modeled values of the parallel capacitance Cp1 and Cp2 and also the parallel resistances Rp1 and Rp2 decrease with the thickness of the material of the at least one layer. The inductance Lp and the quality factor Qmax increase with increasing thickness. The measured and modeled quality factors and impedance data are shown for the material having a thickness of d=110 nm (FIG. 5b), d=160 nm (FIG. 5c) and d=190 nm (FIG. 5d).

[0052] Table 1 shows the modeled values of the equivalent circuit of the material having a thickness of d=110 nm, 160 nm and 190 nm in the LRS with charged domain walls, as per FIG. 5.

TABLE-US-00001 TABLE 1 Modeling of the impedance and the quality factor in FIG. 5. LRS YMO 110 nm YMO 160 nm YMO 190 nm Impedance- Cp.sub.1 240 pF 182 pF 145 pF modeled Rp.sub.1 750 Ω 308.6 Ω 176 Ω Cp.sub.2 270 pF 201 pF 118 pF Rp.sub.2 275.1 Ω 250 Ω 185 Ω RLp 17.85 Ω 9.51 Ω 4.92 Ω Lp 1016.2 nH 1045.75 nH 1064.37 nH Quality Cp.sub.1 265 pF 182 pF 119 pF factor- Rp.sub.1 770 Ω 305 Ω 116 Ω modeled Cp.sub.2 277 pF 141 pF 101 pF Rp.sub.2 280 Ω 250 Ω 175 Ω RLp 9.85 Ω 7.31 Ω 4.72 Ω Lp 1010.37 nH 1041.05 nH 1051.3 nH Q.sub.max 2.61 3.36 3.70

[0053] FIG. 6a depicts an equivalent circuit of the material having charged domain walls in order to model the measured complex impedance Z with dominant capacitive reactance (FIG. 6a). Essentially, modeling is effected by two (Rp, Cp) pairs (Rp.sub.1, Cp.sub.1 and Rp.sub.2, Cp.sub.2). The impedance and the quality factor were modeled by means of the equivalent circuit depicted in FIG. 6a. The modeled values of the parallel capacitance Cp.sub.1 and Cp.sub.2 decrease with the thickness of the material of the at least one layer. The parallel resistances Rp.sub.1 and Rp.sub.2 and the quality factor Q.sub.max increase with the thickness of the material. The measured and modelled quality factors and impedance data are shown for the material having a thickness of d=110 nm (FIG. 6b), d=160 nm (FIG. 6c) and d=190 nm (FIG. 6d).

[0054] Table 2 shows the modeled values of the equivalent circuit of the material having a thickness of d=110 nm, 160 nm and 190 nm in the HRS with charged domain walls, as per FIG. 6.

TABLE-US-00002 TABLE 2 Modeling of the impedance and the quality factor in FIG. 6. HRS YMO 110 nm YMO 160 nm YMO 190 nm Impedance- Cp.sub.1 980 pF 780 pF 130 pF modeled Rp.sub.1 262500 Ω 282500 Ω 302500 Ω Cp.sub.2 294 pF 190 pF 50 pF Rp.sub.2 770 Ω 1770 Ω 2270 Ω Quality Cp.sub.1 540 pF 200 pF 140 pF factor- Rp.sub.1 265500 Ω 310500 Ω 350500 Ω modeled Cp.sub.2 100 pF 50 pF 10 pF Rp.sub.2 550 Ω 1000 Ω 5400 Ω Q.sub.max 3.965 8.775 11.05

[0055] The quality factor and the resonant frequency are set in a controlled manner by means of discrete electronic components supplemented in parallel. This is shown for the material in the LRS having charged domain walls having a thickness of d=110 nm (FIG. 7), d=160 nm (FIG. 8) and d=190 nm (FIG. 9) with different external capacitances C=0.47 μF (FIGS. 7b, 8b, 9b), C=1.00 μF (FIGS. 7c, 8c, 9c) and C=4.00 μF (FIGS. 7d, 8d, 9d). The quality factors and impedance data measured with an external capacitance C were modeled for the material having domain walls in the LRS using the equivalent circuits shown in FIGS. 7a, 8a, 9a, with the external capacitance C being entered with its nominal value into the model.

[0056] This is also shown for the material in the HRS having charged domain walls 5 having a thickness of d=110 nm (FIG. 10), d=160 nm (FIG. 11) and d=190 nm (FIG. 12) with different external inductances L=0.10 mH (FIGS. 10b, 11b, 12b), L=0.68 mH (FIGS. 10c, 11c, 12c) and C=4.00 mH (FIGS. 10d, 11d, 12d). The quality factors and impedance data measured with an external inductance L were modeled for the material having domain walls 5 in the HRS using the equivalent circuits shown in FIGS. 10a, 11a, 12a, with the external inductance L being entered with its nominal value in the model.

LIST OF REFERENCE SYMBOLS

[0057] 1 Non-volatile impedance switch [0058] 2 First contact [0059] 3 Second contact [0060] 4 Layer sequence containing charged domain walls, rare [0061] earth manganate [0062] 5 Charged domain walls [0063] 6 Substrate [0064] 7 Vortex [0065] 8 Insulation structure [0066] 9 Heating and/or cooling element [0067] d Thickness of the layer sequence