Electrical junction for facilitating an integration of electrical crossing

Abstract

An electrical junction comprising a first pair of leads and a second pair of leads. The first pair of leads and the second pair of leads comprise a Weyl semimetal. The junction comprises an electrical crossing arranged between the leads of the first pair and the leads of the second pair and is configured to provide an electrical connection between the leads of the first pair and the leads of the second pair. A related electrical device and a related neural network may be also presented.

Claims

1. An electrical junction comprising: a first pair of leads comprising a Weyl semimetal; a second pair of leads comprising a Weyl semimetal; and an electrical crossing arranged between the leads of the first pair and the leads of the second pair and configured to provide an electrical connection between the leads of the first pair and the leads of the second pair, wherein the Weyl semimetal of the leads of the first pair is magnetized in a first magnetization direction and the Weyl semimetal of the leads of the second pair is magnetized in a second magnetization direction, the second magnetization direction being different from the first magnetization direction.

2. An electrical junction according to claim 1, wherein the first pair of leads and the second pair of leads are configured to transport Weyl-fermions; the first magnetization direction is parallel to a direction of propagation of the Weyl-fermions in the first pair of leads; and the second magnetization direction is antiparallel to the direction of propagation of the Weyl-fermions in the second pair of leads.

3. An electrical junction according to claim 1, wherein the first pair of leads is configured to transport Weyl-fermions of a first chirality; and the second pair of leads is configured to transport Weyl-fermions of a second chirality.

4. An electrical junction according to claim 1, wherein the first pair of leads comprises a plurality of first magnetized elements being configured to apply a directed magnetic field in the first magnetization direction on the Weyl-semimetal of the first pair of leads; and the second pair of leads comprises a plurality of magnetized elements being configured to apply a directed magnetic field in the second magnetization direction on the Weyl-semimetal of the second pair of leads.

5. An electrical junction according to claim 4, wherein the plurality of first magnetized elements and the plurality of second magnetized elements are arranged adjacent to the Weyl-semimetal of the first pair of leads and adjacent to the Weyl semimetal of the second pair of leads respectively.

6. An electrical junction according to claim 4, wherein the plurality of first magnetized elements are embodied as magnetized layers and/or the plurality of second magnetized elements are embodied as magnetized layers.

7. An electrical junction according to claim 4, wherein the plurality of first magnetized elements are embedded in the Weyl semimetal of the first pair of leads and the plurality of second magnetized elements are embedded in the Weyl semimetal of the second pair of leads.

8. An electrical junction according to claim 1, wherein the leads of the first pair of leads and/or the leads of the second pair of leads are arranged in different layers respect to one another.

9. An electrical junction according to claim 4, wherein the plurality of first magnetized elements and/or the plurality of second magnetized elements comprise rare earth magnets.

10. An electrical junction according to claim 4, wherein the plurality of first magnetized elements and/or the plurality of second magnetized elements comprise a material selected from the group consisting of: Neodymium-iron-boron, manganese aluminum, samarium cobalt and aluminum nickel cobalt.

11. An electrical junction according to claim 1, wherein the Weyl-semimetal is selected from the group consisting of: TaAs, NbP, TaP, RPtBi and GdPtBi.

12. An electrical junction according to claim 1, wherein the Weyl-semimetal is a Dirac metal.

13. An electrical junction according to claim 12, wherein the Dirac metal is selected from the group consisting of: Cd.sub.2As.sub.3 and Na.sub.3Bi.

14. An electrical junction according to claim 1, wherein a crossing angle between the leads of the first pair and the leads of the second pair is less than 30 degree, in particular less than 20 degree.

15. An electrical junction according to claim 3, wherein the crossing is configured to provide a distance between the leads of the first pair that is sufficiently small to keep the first chirality of the Weyl-fermions during their transport through the crossing; and to provide a distance between the leads of the second pair that is sufficiently small to keep the second chirality of the Weyl-fermions during their transport through the crossing.

16. An electrical junction according to claim 1, wherein the crossing is configured to provide a distance between the leads of the first pair and the leads of the second pair between 50 nm and 300 nm.

17. An electrical junction comprising: a first pair of leads comprising a Weyl semimetal; a second pair of leads comprising a Weyl semimetal; and an electrical crossing arranged between the leads of the first pair and the leads of the second pair and configured to provide an electrical connection between the leads of the first pair and the leads of the second pair, wherein the crossing comprises a non-magnetized Weyl-semimetal.

18. An electrical device comprising a plurality of junctions according to claim 1.

19. An electrical device comprising a plurality of junctions according to claim 17.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) FIG. 1 shows a schematic view of a neural network according to an embodiment of the invention;

(2) FIG. 2 shows a more detailed view of a part of a neural network according to an embodiment of the invention;

(3) FIG. 3 illustrates a signal flow of an electrical signal in a first pair of leads of an electrical junction according to an embodiment of the invention;

(4) FIG. 4 illustrates a signal flow of an electrical signal in a second pair of leads of an electrical junction according to an embodiment of the invention;

(5) FIG. 5 shows an electrical junction according to an embodiment of the invention comprising magnetized elements adjacent to a Weyl-semimetal;

(6) FIG. 6 shows an electrical junction according to an embodiment of the invention comprising magnetized elements embedded in a Weyl-semimetal;

(7) FIG. 7 shows a top view of an electrical junction according to an embodiment of the invention having a layer of magnetized elements on top of the Weyl-semimetal;

(8) FIG. 8a shows a corresponding cross-sectional view of a first pair of leads and a crossing taken along the section line I-I of FIG. 7;

(9) FIG. 8b shows a corresponding cross-sectional view of a second pair of leads and the crossing taken along the section line II-II of FIG. 7; and

(10) FIG. 9 shows a cross-sectional view of another embodiment taken along the section line I-I of FIG. 7, comprising a vertical junction.

DETAILED DESCRIPTION

(11) FIG. 1 shows a schematic view of a neural network 100 according to an embodiment of the invention. The neural network 100 comprises an input layer 110 comprising a plurality of neurons 10, two hidden layers 120 comprising a plurality of neurons 10 and an output layer 130 comprising a plurality of neurons 10. The neural network 100 comprises a plurality of electrical connections 20 between the neurons 10. The electrical connections 20 connect the outputs of neurons from one layer, e.g. from the input layer110, to the inputs of neurons from the next layer, e.g. one of the hidden layers 120. As illustrated in FIG. 1, the number of such connections 20 may be very large.

(12) FIG. 2 shows a more detailed view of a part of a neural network 200 according to an embodiment of the invention. The neural network 200 comprises four neurons 10a, 10b, 10c and 10d. The two upper neurons 10a and 10b and the two lower neurons 10c and 10d are connected by electrical connections 20a which have no crossings with other electrical connections. The upper neuron 10a and the lower neuron 10d as well as the lower neuron 10c and the upper neuron 10b are connected by electrical connections 20b which cross each other at a crossing 30. The crossing 30 forms a central point of an electrical junction 40.

(13) FIG. 3 and FIG. 4 show an enlarged view of the electrical junction 40 of FIG. 2 and illustrates the desired signal flow of the electrical junction 40.

(14) The electrical junction 40 comprises a first pair of leads comprising a lead 50a and a lead 50b. Furthermore, the electrical junction 40 comprises a second pair of leads comprising a lead 51a and a lead 51b. The leads 50a, 50b as well as the leads 51a and 51b each comprise a Weyl semimetal 55. The electrical crossing 30 is arranged between the leads 50a, 50b of the first pair and the leads 51a, 51b of the second pair. The electrical crossing 30 provides an electrical connection between the leads 50a, 50b as well as between the leads 51a and 51b.

(15) The Weyl semimetal 55 of the leads 50a, 50b of the first pair is magnetized in a first magnetization direction 60 and the Weyl semimetal 55 of the leads 51a, 51b of the second pair is magnetized in a second magnetization direction 61.

(16) The Weyl semimetal 55 is a new state of matter that hosts Weyl fermions as emergent quasiparticles and admits a topological classification that protects Fermi arc surface states on the boundary of a bulk sample. Weyl semimetals have an unusual band structure in which the linearly dispersing valence and conduction bands meet at discrete Weyl points.

(17) According to some embodiments, the Weyl-semimetal 55 may comprise TaAs, NbP or TaP.

(18) According to other embodiments, the Weyl-semimetal 55 may be a Dirac metal. Such a Dirac metal turns into a Weyl semimetal by the application of the magnetic field B. Such a Dirac metal may be e.g. Cd2As3 or Na3Bi.

(19) According to other embodiments, the Weyl semimetal 55 may comprise RPtBi or GdPtBi. These materials turn also into a Weyl semimetal by applying the magnetic field B.

(20) FIG. 3 illustrates a signal flow of an electrical signal 70 in the first pair comprising the leads 50a and 50b. The electrical signal 70 is e.g. a signal that shall be transferred from the neuron 10a to the neuron 10d. Accordingly, it is desired that the electrical signal 70 is forwarded from the lead 50a only to the lead 50b. More particularly, according to embodiments of the invention any crosstalk of the electrical signal 70 into the lead 51b of the second pair shall be minimized and preferably completely avoided. The electrical signal 70 may be in particular embodied as Weyl-fermions that are transported by the leads 50a, 50b of the first pair.

(21) FIG. 4 illustrates a signal flow of an electrical signal 71 in the second pair comprising the leads 51a and 51b. The electrical signal 71 is e.g. a signal that shall be transferred from the neuron 10c to the neuron 10b. Accordingly, it is desired that the electrical signal 71 is forwarded from the lead 51a only to the lead 51b. More particularly, according to embodiments of the invention any crosstalk of the electrical signal 71 into the lead 50b of the first pair shall be minimized and preferably completely avoided. The electrical signal 71 may be in particular embodied as Weyl-fermions that are transported by the leads 51a, 51b of the second pair.

(22) The separation of the two electrical signals 70, 71 is achieved by the different magnetization directions of the Weyl semimetal 55. More particularly, the first magnetization direction 60 of the leads 50a, 50b of the first pair is parallel to the direction of propagation of the electrical signal 70, i.e. the Weyl-fermions in the first pair of leads. And the second magnetization direction 61 of the leads 51a, 51b of the second pair is antiparallel to the direction of propagation of the electrical signal 71, i.e. the Weyl-fermions in the second pair of leads. As a result of such a different magnetization of the leads 50a, 50b of the first pair and the leads 51a, 51b of the second pair, the leads 50a, 50b of the first pair are configured to transport Weyl-fermions of a first chirality and the leads 51a, 51b of the second pair are configured to transport Weyl-fermions of a second chirality. According to embodiments, the first chirality is a right-handed chirality and the second chirality is a left-handed chirality. According to other embodiments, the second chirality is a right-handed chirality and the first chirality is a left-handed chirality.

(23) The chirality may be defined as the product of the spin of the Weyl-fermions and the direction of propagation of the Weyl-fermions.

(24) Between the leads 50a, 50b of the first pair and the leads 51a, 51b of the second pair a crossing angle is provided. The crossing angle is according to preferred embodiments less than 30 degree and according to even more preferred embodiments less than 20 degree. Such rather small crossing angles facilitate an efficient separation of the electrical signals 70 and 71 and reduce and/or minimize any crosstalk between the different pairs of leads.

(25) According to preferred embodiments, the crossing 30 provides a distance d.sub.1 between the leads 50a and 50b of the first pair that is sufficiently small to keep the first chirality of the Weyl-fermions during their transport through the crossing 30. The distance d.sub.1 may be also denoted as transport length.

(26) Furthermore, according to preferred embodiments, the crossing 30 provides a distance d.sub.2 between the leads 51a and 51b of the second pair that is sufficiently small to keep the second chirality of the Weyl-fermions during their transport through the crossing 30. The distance d.sub.2 may be also denoted as transport length.

(27) According to embodiments the distance d.sub.1 between the leads 50a and 50b of the first pair and the distance d.sub.2 between the leads 51a, 51b of the second pair is between 100 nm and 300 nm.

(28) According to the embodiment of FIGS. 3 and 4, the crossing 30 has a circular shape. However, according to other embodiments other shapes may be provided, e.g. hexagonal or octagonal shapes or other suitable shapes.

(29) The material of the crossing 30 may be according to embodiments a metallic material. According to preferred embodiments the material of the crossing may be a non-magnetized Weyl-semimetal.

(30) FIG. 5 shows an electrical junction 500 according to an embodiment of the invention.

(31) The electrical junction 500 comprises a first pair of leads comprising a lead 50a and a lead 50b. Furthermore, the electrical junction 500 comprises a second pair of leads comprising a lead 51a and a lead 51b. The leads 50a, 50b as well as the leads 51a and 51b each comprise a Weyl semimetal 55. An electrical crossing 30 is arranged between the leads 50a, 50b of the first pair and the leads 51a, 51b of the second pair.

(32) The first pair 50 of leads 50a, 50b comprises first magnetized elements 80 which are arranged adjacent to the Weyl-semimetal of the first pair of leads 50a, 50b. The magnetized elements 80 apply a directed magnetic field B in the first magnetization direction 60 on the Weyl-semimetal 55 of the first pair of leads 50a, 50b. The magnetized elements 80 are electrically insulated from the Weyl semimetal 55 by an insulating layer 65.

(33) The second pair of leads 51a, 51b comprises second magnetized elements 81 which are arranged adjacent to the Weyl-semimetal of the second pair of leads 51a, 51b. The magnetized elements 81 apply a directed magnetic field B in the second magnetization direction 61 on the Weyl-semimetal of the second pair of leads 51a, 51b.

(34) The magnetized elements 81 are electrically insulated from the Weyl semimetal 55 by an insulating layer 65.

(35) Accordingly, the Weyl semimetal 55 of the leads 50a, 50b of the first pair is magnetized in the first magnetization direction 60 and the Weyl semimetal of the leads 51a, 51b of the second pair is magnetized in the second magnetization direction 61.

(36) According to embodiments, the first magnetized elements 80 and the second magnetized elements 81 may comprise rare earth magnets. According to other embodiments, the magnetized elements 80, 81 may comprise Neodymium-iron-boron, mangan aluminum, samarium cobalt or aluminum nickel cobalt.

(37) FIG. 6 shows an electrical junction 600 according to an embodiment of the invention.

(38) The electrical junction 600 comprises a first pair of leads comprising a lead 50a and a lead 50b. Furthermore, the electrical junction 600 comprises a second pair of leads comprising a lead 51a and a lead 51b. The leads 50a, 50b as well as the leads 51a and 51b each comprise a Weyl semimetal 55. The Weyl semimetal 55 is illustrated with a grey-shading. An electrical crossing 30 is arranged between the leads 50a, 50b of the first pair and the leads 51a, 51b of the second pair.

(39) The first pair of leads 50a, 50b comprises a plurality of first magnetized elements 80 which are embedded in the Weyl semimetal of the leads 50a, 50b. The first magnetized elements 80 are illustrated with white dots in FIG. 6. The embedded magnetized elements 80 may be in particular atoms. The embedded magnetized elements 80 may be integrated into the Weyl-semimetal e.g. by magnetic doping techniques. The magnetized elements 80 apply a directed magnetic field B in the first magnetization direction 60 on the Weyl-semimetal of the first pair of leads 50a, 50b.

(40) The second pair of leads 51a, 51b comprises a plurality of second magnetized elements 81 which are embedded in the Weyl semimetal of the leads 51a, 51b. The second magnetized elements 81 are illustrated with white dots in FIG. 6. The embedded magnetized elements 81 may be in particular atoms. The embedded magnetized elements 81 may be integrated into the Weyl-semimetal e.g. by magnetic doping techniques. The second magnetized elements 81 apply a directed magnetic field B in the second magnetization direction 61 on the Weyl-semimetal of the second pair of leads 51a, 51b.

(41) FIG. 7 shows a top view of an electrical junction 700 according to an embodiment of the invention.

(42) The electrical junction 700 comprises a first pair of leads comprising a lead 50a and a lead 50b. Furthermore, the electrical junction 700 comprises a second pair of leads comprising a lead 51a and a lead 51b. The leads 50a, 50b as well as the leads 51a and 51b each comprise a Weyl semimetal. An electrical crossing 30 is arranged between the leads 50a, 50b of the first pair and the leads 51a, 51b of the second pair.

(43) FIG. 8a shows a corresponding cross-sectional view of the first pair and the crossing 30 taken along the section line I-I of FIG. 7.

(44) FIG. 8b shows a corresponding cross-sectional view of the second pair and the crossing 30 taken along the section line II-II of FIG. 7.

(45) The first pair of leads 50a, 50b comprises first magnetized elements 80 which are embodied as magnetized layers and are arranged on top of the Weyl semimetal 55 of the first pair of leads 50a, 50b. An insulating layer 65 is provided between the first magnetized elements 80 and the Weyl semimetal 55. The first magnetized elements 80 apply a directed magnetic field B in the first magnetization direction 60 on the Weyl-semimetal 55 of the first pair of leads 50a, 50b.

(46) The second pair of leads 51a, 51b comprises second magnetized elements 81 which are also embodied as magnetized layers and are arranged on top of the Weyl semimetal 55 of the second pair of leads 51a, 51b. An insulating layer 65 is provided between the second magnetized elements 81 and the Weyl semimetal 55. The second magnetized elements 81 apply a directed magnetic field B in the second magnetization direction 61 on the Weyl-semimetal 55 of the second pair of leads 51a, 51b.

(47) FIG. 9 shows a cross-sectional view of another embodiment of an electrical junction, taken along the section line I-I of FIG. 7. The electrical junction according to this embodiment comprises a lead 50a of the first pair of leads and a lead 50b of the first pair which are arranged in different vertical layers, i.e. in a different vertical positions in the vertical z-direction. More particularly, the lead 50a is arranged in a vertical layer VL1 and the lead 50b in a vertical layer VL2. In other words, the lead 50b is arranged in a higher layer above the lead 50a with respect to the vertical z-direction.

(48) The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.