Circuits and devices based on spin hall effect to apply a spin transfer torque with a component perpendicular to the plane of magnetic layers

Patent metadata

Field	Value
Publication number	US-2016276006-A1
Application number	US-201415030291-A
Country	US
Kind code	A1
Filing date	Oct 20, 2014
Priority date	Oct 18, 2013
Publication date	Sep 22, 2016
Grant date	—

Abstract

A device based on a spin Hall effect and spin-transfer torque (STT) effect is provided to include a magnetic tunneling junction (MTJ) element including a free magnetic layer structured to have a magnetization direction that can be changed by spin-transfer torque; an electrically conducting magnetic layer structure exhibiting a spin Hall effect (SHE) and, in response to an applied in-plane charge current, generating a spin-polarized current of a magnetic moment oriented in a predetermined direction having both an in-plane magnetic moment component parallel to a surface of the electrically conducting magnetic layer structure and a perpendicular magnetic moment component perpendicular to the surface of the electrically conducting magnetic layer structure. The magnetization direction of the free magnetic layer is capable of being switched by the spin-polarized current via a spin-transfer torque (STT) effect. This device can be configured in a 3-terminal configuration.

First claim

What is claimed is what is described and illustrated, including:

1 . A device based on a spin Hall effect and spin-transfer torque (STT) effect, comprising:
a magnetic tunneling junction (MTJ) element including a free magnetic layer, a fixed magnetic layer, and a tunnel barrier layer sandwiched between the free magnetic layer and the fixed magnetic layer, the free magnetic layer structured to have a magnetization direction that can be changed by spin-transfer torque; an electrically conducting magnetic layer structure exhibiting a spin Hall effect (SHE) and, in response to an applied in-plane charge current, generating a spin-polarized current of a magnetic moment oriented in a predetermined direction having both an in-plane magnetic moment component parallel to a surface of the electrically conducting magnetic layer structure and a perpendicular magnetic moment component perpendicular to the surface of the electrically conducting magnetic layer structure; and wherein the magnetization direction of the free magnetic layer is capable of being switched by the spin-polarized current via a spin-transfer torque (STT) effect.

2 . The device of claim 1 , wherein both the free magnetic layer and the fixed magnetic layer have perpendicular magnetic anisotropy.

3 . The device of claim 1 , wherein both the free magnetic layer and the fixed magnetic layer have in-plane magnetic anisotropy.

4 . The device of claim 1 , wherein the electrically conducting magnetic layer structure has a thickness that is less than or equal to five times of a spin diffusion length of the electrically conducting magnetic layer structure but greater than the spin relaxation length.

5 . The device of claim 1 , wherein the predetermined direction and the surface of the electrically conducting magnetic layer structure form an out-of-plane angle between 0 and 90 degrees.

6 . The device of claim 5 , wherein the out-of-plane angle is at or around 45 degrees.

7 . The device of claim 1 , wherein the electrically conducting magnetic layer structure includes a ferromagnetic material that exhibits a magnetization in the predetermined direction.

8 . The device of claim 1 , wherein the electrically conducting magnetic layer structure includes a ferrimagnetic material that exhibits a magnetization in the predetermined direction.

9 . The device of claim 1 , further comprising:
a first electrical contact layer in contact with the fixed magnetic layer; a second electrical contact in contact with a first location of the electrically conducting magnetic layer structure; a third electrical contact in contact with a second location of the electrically conducting magnetic layer structure, wherein the first and second locations on two sides of the MTJ element; a MTJ circuit coupled between the first electrical contact and one of the second and third electrical contacts to supply a sensing current or a voltage to the MTJ element; and a charge current circuit coupled between the second and third electrical contacts to supply the in-plane charge current into the electrically conducting magnetic layer structure.

10 . The device of claim 1 , further comprising:
a non-magnetic spacer layer which is sandwiched between the free magnetic layer of the MTJ element and the electrically conducting magnetic layer structure, wherein the non-magnetic spacer layer is structured to transmit the spin-polarized current generated by the electrically conducting magnetic layer structure to the free magnetic layer to apply a spin-transfer torque orientated in the predetermined direction on the free magnetic layer.

11 . The device of claim 1 , wherein:
the electrically conducting magnetic layer structure includes a material that is electrically conducting, is magnetic to have a magnetization along the predetermined direction, and exhibits the spin Hall effect (SHE).

12 . The device of claim 1 , wherein:
the electrically conducting magnetic layer structure includes a non-magnetic layer that is electrically conducting and exhibits the spin Hall effect (SHE), and a magnetic layer that has a magnetization along the predetermined direction as a spin filter.

13 . The device of claim 1 , wherein:
the magnetic free layer includes two magnetic domains having opposite magnetization directions and a magnetic domain wall between the two magnetic domains is changeable in position within the magnetic free layer in response to the spin-polarized current.

14 . The device of claim 13 , wherein the magnetic domains have magnetization directions that are parallel to the magnetic free layer.

15 . The device of claim 13 , wherein the magnetic domains have magnetization directions that are perpendicular to the magnetic free layer.

16 . A magnetic tunneling junction memory device based on a spin Hall effect and spin-transfer torque (STT) effect in a three-terminal circuit configuration, comprising:
an array of memory cells for storing data; and a memory control circuit coupled to the array of memory cells and operable to read or write data in the memory cells, wherein each memory cell includes:
a magnetic tunneling junction (MTJ) that includes (1) a pinned magnetic layer having a fixed magnetization direction, (2) a free magnetic layer having a magnetization direction that is changeable, and (3) a non-magnetic junction layer between the magnetic free layer and the pinned magnetic layer and formed of an insulator material sufficiently thin to allow tunneling of electrons between the magnetic free layer and the pinned magnetic layer;
a spin Hall effect metal layer structure that includes a metal exhibiting a large spin Hall effect to react to a charge current directed into the spin Hall effect metal layer to produce a spin-polarized current that is perpendicular to the charge current and has spin polarization components that are perpendicular and parallel to the layers of MTJ, the spin Hall effect metal layer structure being parallel to and adjacent to the free magnetic layer to direct the spin-polarized current generated in the spin Hall effect metal layer into the free magnetic layer;
a first electrical terminal in electrical contact with the MTJ from a side having the pinned magnetic layer; and
second and third electrical terminals in electrical contact with two contact locations of the spin Hall effect metal layer structure on two opposite sides of the free magnetic layer to supply the charge current in the spin Hall effect metal layer structure; and
wherein the memory control circuit is configured to be operable in a writing mode to apply the charge current in the spin Hall effect metal layer structure to set or switch the magnetization direction of the free magnetic layer to a desired direction for representing a stored bit, and wherein the memory control circuit is further configured to be operable in a read mode to apply a read voltage to the first electrical terminal to supply a read current tunneling across the MTJ between the first electrical terminal and the spin Hall effect metal layer structure, without switching the magnetization direction of the free magnetic layer, to sense the magnetization direction of the free magnetic layer that represents the stored bit in the MTJ.

17 . The device as in claim 16 , wherein:
the first electrical terminal is in electrical contact with the MTJ from a side having the pinned magnetic layer to receive a gate voltage that modifies a current threshold of a spin-polarized current flowing across the MTJ for switching the magnetization of the free magnetic layer; and the memory contro

Assignees

• Univ Cornell

Inventors

• Ralph Daniel C
• Buhrman Robert A

Classifications

• H01L43/06

  Electricity · mapped topic

• G11C11/161 Primary

  details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell · CPC title

• H01L27/226

  Electricity · mapped topic

• G11C11/1675

  Writing or programming circuits or methods · CPC title

• H01L43/08

  Electricity · mapped topic