Direct Electrical Detection of Current-Induced Spin Polarization Due to Spin-Momentum Locking in Topological Insulators

Patent metadata

Field	Value
Publication number	US-2016169986-A1
Application number	US-201514934240-A
Country	US
Kind code	A1
Filing date	Nov 6, 2015
Priority date	Dec 10, 2014
Publication date	Jun 16, 2016
Grant date	—

Abstract

A method for directly electrically generating and detecting spin polarization in topological insulators comprising depositing a first and fourth contact on a layer of Bi 2 Se 3 and applying a current between the contacts, which creates a net spin polarization due to spin-momentum locking. A second (comprising ferromagnet/tunnel barrier) and third contact are deposited for detecting the spin polarization. A device for directly electrically generating and detecting the current-generated spin polarization in topological insulators, comprising a first and fourth contact on a layer of Bi 2 Se 3 and a second contact comprising a ferromagnet/oxide tunnel barrier contact as a detector, and a third contact comprising nonmagnetic metal as a reference contact, a current to the first and fourth contact to produce a net spin polarization, and the spin polarization manifesting as a voltage between the second (magnetic) and third (reference) contacts.

First claim

What we claim is:

1 . A method of making a device for directly electrically generating and detecting spin polarization in topological insulators, comprising:
depositing a first contact and fourth contact on a layer of Bi 2 Se 3 ; depositing a second contact and third contact wherein the second contact comprises a ferromagnet/oxide tunnel barrier contact and wherein the third contact comprises a nonmagnetic metal contact; applying a current between the first contact and fourth contact; creating a net spin polarization due to spin-momentum locking; and detecting the spin polarization between the second contact and the third contact.

2 . The method for directly electrically generating and detecting spin polarization in topological insulators of claim 1 wherein the ferromagnet/oxide tunnel barrier comprises a layer of Fe and a layer of Al 2 O 3 .

3 . The method for directly electrically generating and detecting spin polarization in topological insulators of claim 1 wherein the ferromagnet/oxide tunnel barrier comprises a layer of Co and a layer of MgO on top of a layer of graphene.

4 . The method for directly electrically generating and detecting spin polarization in topological insulators of claim 1 wherein the current is an unpolarized bias current.

5 . The method for directly electrically generating and detecting spin polarization in topological insulators of claim 1 wherein the step of detecting the spin polarization of the surface spin due to spin-momentum locking is its projection onto the detector contact magnetization manifests as a voltage.

6 . The method for directly electrically generating spin polarization in topological insulators of claim 1 wherein the step of detecting the spin polarization comprises detecting the voltage between the second ferromagnetic/oxide tunnel barrier contact and the third contact.

7 . The method for directly electrically generating spin polarization in topological insulators of claim 6 wherein the magnetization of the third contact determines the spin detection axis and the projection of the TI spin polarization onto the spin detection axis is detected electrically as a voltage.

8 . A method for direct electrical access to current-induced spin polarization due to spin-momentum locking of the topologically protected surface states in topological insulators comprising:
applying an unpolarized bias current; creating a net spin polarization; creating a spin accumulation; creating spin polarized current flowing through surface states; detecting directly electrically the spin accumulation; and utilizing the spin polarized surface states for spintronic/electronic applications.

9 . The method for direct electrical access to current-induced spin polarization due to spin-momentum locking of the topologically protected surface states in topological insulators of claim 8 further comprising the step of:
utilizing a ferromagnetic thin film surface contact to detect the spin polarization.

10 . The method for direct electrical access to current-induced spin polarization due to spin-momentum locking of the topologically protected surface states in topological insulators of claim 9 wherein the ferromagnetic thin film surface contact is magnetized and wherein the magnetization of the contact determines the spin detection axis.

11 . The method for direct electrical access to current-induced spin polarization due to spin-momentum locking of the topologically protected surface states in topological insulators of claim 10 further comprising the step of:
detecting electrically as a voltage a projection of the topological insulator spin polarization onto the spin detection axis.

11 . A device for directly electrically generating and detecting the current-generated spin polarization in topological insulators, comprising:
a first contact and fourth contact on a layer of Bi 2 Se 3 ; a second contact comprising a ferromagnet/oxide tunnel barrier contact on a layer of Bi 2 Se 3 ; wherein the second contact is a detector; a third contact on the layer of Bi 2 Se 3 ; wherein the third contact is a reference; a current to the first contact and the fourth contact; a net spin polarization; and the spin polarization manifesting as a voltage between the second contact and the third contact.

12 . The device for directly electrically generating and detecting the current-generated spin polarization in topological insulators of claim 11 wherein the ferromagnet/oxide tunnel barrier comprises a layer of Fe and a layer of Al 2 O 3 .

13 . The device for directly electrically generating and detecting the current-generated spin polarization in topological insulators of claim 12 wherein the ferromagnet/oxide tunnel barrier comprises a layer of Co and a layer of MgO on top of a layer of graphene.

14 . The device for directly electrically generating and detecting the current-generated spin polarization in topological insulators of claim 13 wherein the current is an unpolarized bias current.

15 . A device for directly electrically detecting current-generated spin polarization in topological insulators, comprising:
a first contact and fourth contact on a layer of Bi 2 Se 3 to produce a spin; a second magnetic contact comprising a ferromagnet/oxide tunnel barrier contact as a detector; a third reference contact comprising nonmagnetic metal as the reference contact; a current to the first contact and fourth contact to produce a net spin polarization; and the spin polarization manifesting as a voltage between the second magnetic contact and third reference contact.

16 . The device for directly electrically detecting current-generated spin polarization in topological insulators of claim 15 wherein the ferromagnet/oxide tunnel barrier comprises a layer of Fe and a layer of Al 2 O 3 .

17 . The device for directly electrically detecting current-generated spin polarization in topological insulators of claim 15 wherein the ferromagnet/oxide tunnel barrier comprises a layer of Co and a layer of MgO on top of a layer of graphene.

18 . The device for directly electrically detecting current-generated spin polarization in topological insulators of claim 15 wherein the current is an unpolarized bias current.

19 . The device for directly electrically detecting current-generated spin polarization in topological insulators of claim 15 the spin polarization of the surface spin due to spin-momentum locking is its projection onto the detector contact magnetization manifests as a voltage.

Assignees

• Us Government

Inventors

• Li Connie H
• Van T Erve Olaf M T
• Robinson Jeremy T
• Liu Ying
• Li Lian
• Jonker Berend T

Classifications

• H01L43/10

  Electricity · mapped topic

• H01L43/08

  Electricity · mapped topic

• G01R33/096 Primary

  anisotropic magnetoresistance sensors · CPC title

• H01L43/12

  Electricity · mapped topic

• H01L43/02

  Electricity · mapped topic