MR sensors having layer orientation control using SOT current
Methods and apparatus for an MR device having a ferromagnetic material, a heavy metal layer configured to flow a charge current, and an insulating layer between the ferromagnetic material and the heavy metal layer. The insulating layer is configured to electrically insulate and to magnetically couple the heavy metal layer and the ferromagnetic layer for generating a field like (FL) field in the ferromagnetic material in response to the charge current. In some embodiments, the MR device comprises a TMR device having a free layer or a reference layer oriented by the charge current. In other embodiments, the MR device comprises a GMR device.
1 . A device for sensing an applied magnetic field, comprising:
a magnetoresistance (MR) device having a ferromagnetic material, wherein the MR device comprises first and second MR elements having the ferromagnetic material in common, wherein the first and second MR elements are configured to generate a sense current in response to the applied magnetic field;
a heavy metal layer configured to flow a charge current; and
an insulating layer between the ferromagnetic material and the heavy metal layer configured to electrically insulate and to magnetically couple the heavy metal layer and the ferromagnetic layer for generating a field like (FL) field in the ferromagnetic material in response to the charge current.
2 . The device according to claim 1 , wherein the MR device comprises a GMR device.
3 . The device according to claim 1 , wherein the MR device comprises a TMR device having pillars.
4 . The device according to claim 3 , wherein the TMR device comprises a free layer, a barrier, and a reference layer.
5 . The device according to claim 4 , wherein an orientation of the free layer is controlled by the charge current.
6 . The device according to claim 4 , wherein an orientation of the reference layer is controlled by the charge current.
7 . The device according to claim 1 , wherein the insulating layer is configured to conduct a spin current to generate the FL field.
8 . The device according to claim 1 , wherein the insulating layer is configured to generate the FL field via Rashba coupling.
9 . The device according to claim 1 , wherein the insulating layer is configured to generate a damping like field.
10 . The device according to claim 1 , wherein the insulating layer comprises a ferrimagnetic insulator.
11 . The device according to claim 1 , wherein the insulating layer comprises a ferromagnetic insulator.
12 . The device according to claim 1 , wherein the insulating layer comprises as first layer configured to provide electrical isolation and a second layer to provide magnetic coupling of the heavy metal layer and the ferromagnetic layer.
13 . The device according to claim 1 , wherein the insulating layer is between first and second portions of the ferromagnetic layer, wherein the first portion extends to a barrier and the second portion extends to the heavy metal layer.
14 . The device according to claim 13 , wherein the first and second portions of the ferromagnetic layer are magnetically coupled through the insulating layer.
15 . The device according to claim 1 , wherein the device comprises more than two TMR pillars.
16 . The device according to claim 1 , wherein the charge current is configured to control a sensitivity of the device for an applied external field parallel to a direction of the charge current and perpendicular to the FL field on a free layer of the ferromagnetic material.
17 . The device according to claim 1 , wherein the charge current is configured to at least partially cancel an external field perpendicular to a direction of the charge current and parallel to the FL field on a free layer of the ferromagnetic material.
18 . The device according to claim 1 , wherein the charge current comprises a first charge current configured to generate the FL field in a direction of an applied external field and a second charge current configure to control a sensitivity of the device for the applied external field.
19 . The device according to claim 1 , wherein the device is configured to sense a external field and generate a feedback current corresponding to the external field and inject the feedback current into the leavy metal layer to form at least a portion of the charge current.
20 . The device according to claim 1 , wherein the MR device comprises at least first, second, third, and fourth TMR pillars connected in series, wherein at least two of the at least first, second, third, and fourth TMR pillars share a common free layer.
21 . The device according to claim 20 , wherein the common layer is disposed on the insulating layer.
22 . The device according to claim 1 , wherein the MR device comprises at least first and second TMR pillars each having respective free layers on the insulating layer, and further including a metal material connecting the free layers of the first and second pillars.
23 . The device according to claim 1 , wherein the charge current comprises first and second charge currents configured to orient a reference layer of a TMR device to any orientation within a three hundred and sixty degree rotation in a plane of the reference layer.
24 . The device according to claim 1 , wherein the device comprises a TMR device having a resistance variation with an angle between the orientation of the reference layer and an orientation angle of a free layer set by an applied external field.
25 . The device according to claim 1 , wherein the charge current comprises first and second charge currents configured to cancel 1/f electrical noise, where f is switching frequency.
26 . A method, comprising:
employing a magnetoresistance (MR) device having a ferromagnetic material, wherein the MR device comprises first and second MR elements having the ferromagnetic material in common, wherein the first and second MR elements are configured to generate a sense current in response to an applied magnetic field;
employing a heavy metal layer configured to flow a charge current; and
configuring an insulating layer between the ferromagnetic material and the heavy metal layer configured to electrically insulate and to magnetically couple the heavy metal layer and the ferromagnetic layer for generating a field like (FL) field in the ferromagnetic material in response to the charge current.
27 . The method according to claim 26 , wherein the MR device comprises a free layer, a barrier, and a reference layer.
28 . The method according to claim 27 , further including controlling an orientation of the free layer by the charge current.
29 . The method according to claim 27 , further including controlling an orientation of the reference layer by the charge current.
30 . The method according to claim 26 , wherein the insulating layer is configured to conduct a spin current to generate the FL field.
31 . The method according to claim 26 , wherein the charge current comprises first and second charge currents configured to orient a reference layer of a TMR device to any orientation within a three hundred and sixty degree rotation in a plane of the reference layer.
32 . The method according to claim 26 , wherein the MR device has resistance variation with an angle between an orientation of a reference layer and an orientation angle of a free layer set by an applied external field.
33 . A device, comprising:
a magnetoresistance (MR) device having a free layer, a barrier, and a reference layer; and
a heavy metal layer connected to the MR device and configured to flow first and second charge currents, wherein the first and second charge currents are configured to generate a field like (FL) field to orient the reference layer in a range from 0 to 360 degrees.