SOT film stack for differential reader

Patent metadata

Field	Value
Publication number	US-11094338-B1
Application number	US-202017029833-A
Country	US
Kind code	B1
Filing date	Sep 23, 2020
Priority date	Jul 9, 2020
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

The present disclosure generally relates to spin-orbital torque (SOT) differential reader designs. The SOT differential reader is a multi-terminal device comprising a first seed layer, a first spin hall effect (SHE) layer, a first interlayer, a first free layer, a gap layer, a second seed layer, a second SHE layer, a second free layer, and a second interlayer. The gap layer is disposed between the first SHE layer and the second SHE layer. The materials and dimensions used for the first and second seed layers, the first and second interlayers, and the first and second SHE layers affect the resulting spin hall voltage converted from spin current injected from the first free layer and the second free layer, as well as the ability to tune the first and second SHE layers. Moreover, the SOT differential reader improves reader resolution without decreasing the shield-to-shield spacing (i.e., read-gap).

First claim

What is claimed is:

1. A magnetic sensor, comprising:
a spin orbital torque (SOT) element, the SOT element comprising:
a silicide seed multilayer disposed over a first shield;
a first spin hall effect layer disposed over the silicide seed multilayer, the first spin hall effect layer comprising BiSb or an alloy thereof having a crystalline structure of (012);
a first interlayer layer disposed over the first spin hall effect layer;
a first free layer disposed over the first interlayer layer;
a seed layer disposed over the first free layer;
a second free layer disposed over the seed layer;
a second interlayer disposed over the second free layer;
a second spin hall effect layer disposed over the second interlayer layer, the second spin hall effect layer comprising BiSb or an alloy thereof having a crystalline structure of (001); and
a cap layer disposed over the second spin hall effect layer.

2. The magnetic sensor of claim 1 , wherein the seed layer comprises NiFeTa having a thickness of about 5 Angstroms to about 15 Angstroms, and wherein the silicide seed multilayer comprises a Si layer having a thickness of about 16 Angstroms, a first Cu layer having a thickness of about 1 Angstrom, a NiFe layer having a thickness of about 8 Angstroms, and a second Cu layer having a thickness of about 1 Angstrom.

3. The magnetic sensor of claim 1 , wherein the first interlayer comprises a NiCu layer having a thickness of about 2 Angstroms to about 4 Angstroms and a NiFeTa layer having a thickness of about 5 Angstroms to about 15 Angstroms, and wherein the second interlayer comprises a NiFeTa layer having a thickness of about 5 Angstroms to about 15 Angstroms and a NiAl layer having a thickness of about 5 Angstroms to about 20 Angstroms.

4. The magnetic sensor of claim 1 , wherein the first spin hall effect layer has a thickness of about 240 Angstroms to about 250 Angstroms, wherein the second spin hall effect layer has a thickness of about 450 Angstroms to about 470 Angstroms, and wherein the cap layer comprises a NiCu layer and a NiFeTa layer.

5. The magnetic sensor of claim 1 , wherein the magnetic recording head is configured to:
match an amplitude of the first spin hall effect layer to the second spin hall effect layer; and
match a spin current from the first free layer to a spin current from the second free layer.

6. The magnetic sensor of claim 1 , further comprising:
a gap layer disposed between the first free layer and the seed layer; and
an electrical lead recessed from a media facing surface, the electrical lead being in contact with the gap layer and a second shield, wherein the first free layer, the second free layer, the gap layer, the first spin hall effect layer, and the second spin hall effect layer are disposed at the media facing surface.

7. The magnetic sensor of claim 1 , wherein the second spin hall effect layer has a Sb concentration of about 30% to about 40%, and wherein the first spin hall effect layer has a Sb concentration of about 7% to about 17%.

8. A magnetic recording device comprising the magnetic sensor of claim 1 .

9. A magnetic sensor, comprising:
a spin orbital torque (SOT) element, the SOT element comprising:
a silicide seed multilayer disposed over a first shield;
a first spin hall effect layer disposed over the silicide seed multilayer, the first spin hall effect layer comprising BiSb or an alloy thereof having a crystalline structure of (012);
a first interlayer layer disposed over the first spin hall effect layer, the first interlayer comprising a NiCu layer and a NiFeTa layer;
a first free layer disposed over the first interlayer layer;
a seed layer disposed over the first free layer;
a second free layer disposed over the seed layer;
a second interlayer disposed over the second free layer, the second interlayer comprising a NiFeTa layer and a NiAl layer; and
a second spin hall effect layer disposed over the second interlayer layer, the second spin hall effect layer comprising BiSb or an alloy thereof having a crystalline structure of (001).

10. The magnetic sensor of claim 9 , further comprising:
a cap layer disposed over the second spin hall effect layer, the cap layer comprising a NiCu layer having a thickness of about 5 Angstroms to about 10 Angstroms and a NiFeTa layer having a thickness of about 10 Angstroms to about 20 Angstroms; and
a gap layer disposed between the first free layer and the seed layer, the gap layer being configured to act as an electrical lead.

11. The magnetic sensor of claim 9 , wherein the silicide seed multilayer comprises a Si layer having a thickness of about 16 Angstroms, a first Cu layer having a thickness of about 1 Angstrom, a NiFe layer having a thickness of about 8 Angstroms, and a second Cu layer having a thickness of about 1 Angstrom, and wherein the seed layer comprises NiFeTa having a thickness of about 5 Angstroms to about 15 Angstroms.

12. The magnetic sensor of claim 9 , wherein the NiCu layer of the first interlayer has a thickness of about 2 Angstroms to about 4 Angstroms and the NiFeTa layer of the first interlayer has a thickness of about 5 Angstroms to about 15 Angstroms, and wherein the NiFeTa layer of the second interlayer has a thickness of about 5 Angstroms to about 15 Angstroms and the NiAl layer of the second interlayer has a thickness of about 5 Angstroms to about 20 Angstroms.

13. The magnetic sensor of claim 9 , wherein the second spin hall effect layer comprises a higher Sb concentration than the first spin hall effect layer, and wherein the second spin hall effect layer is thicker than the first spin hall effect layer.

14. A magnetic recording device comprising the magnetic sensor of claim 9 .

15. A magnetic sensor, comprising:
a spin orbital torque (SOT) element, the SOT element comprising:
a silicide seed multilayer disposed over a first shield, the silicide seed multilayer comprising a Si layer, a first Cu layer, a NiFe layer, and a second Cu layer;
a first spin hall effect layer disposed over the silicide seed multilayer, the first spin hall effect layer comprising BiSb or an alloy thereof having a crystalline structure of (012);
a first interlayer layer disposed over the first spin hall effect layer, the first interlayer comprising a NiCu layer and a NiFeTa layer;
a first free layer disposed over the first interlayer layer;
a gap layer disposed over the first free layer;
a seed layer disposed over the gap layer, the seed layer comprising NiFeTa;
a second free layer disposed over the gap layer;
a second interlayer disposed over the second free layer, the second interlayer comprising a NiFeTa layer and a NiAl layer;
a second spin hall effect layer disposed over the second interlayer layer, the second spin hall effect layer comprising BiSb or an alloy thereof having a crystalline structure of (001), wherein the second spin hall effect layer has a greater thickness and a higher Sb concentration than the first spin hall effect layer; and
a cap layer comprising a NiCu layer and a NiFeTa layer disposed over the second spin hall effect layer.

16. The magnetic sensor of claim 15 , wherein the Si layer of the silicide seed multilayer has a thickness of about 16 Angstroms, the first Cu layer of the silicide seed multilayer has a thickness of about 1 Angstrom, the NiFe layer of the silicide seed multilayer has a thickness of about 8 Angstroms, and the second Cu layer of the silicide seed multilayer has a thickness of about 1 Angstrom.

17. The magnetic sensor of claim 15 , wherein the seed layer has a thickness of about 5 Angstroms to about 15 Angstroms.

Assignees

• Western Digital Tech Inc

Inventors

• Hwang Cherngye
• Liu Xiaoyong
• Le Quang
• Ho Kuok San
• Takano Hisashi
• York Brian R

Classifications

• G11B5/39 Primary

  using magneto-resistive devices {or effects} · CPC title

• G11B5/315 Primary

  Shield layers on both sides of the main pole, e.g. in perpendicular magnetic heads · CPC title

• G11B5/11

  Shielding of head against electric or magnetic fields · CPC title