Two-dimensional magnetic recording reader with dual free layer magnetic tunnel junction

Patent metadata

Field	Value
Publication number	US-11410690-B2
Application number	US-202016899366-A
Country	US
Kind code	B2
Filing date	Jun 11, 2020
Priority date	Jun 11, 2020
Publication date	Aug 9, 2022
Grant date	Aug 9, 2022

Abstract

The present disclosure generally related to a two dimensional magnetic recording (TDMR) read head having a magnetic tunnel junction (MTJ). Both the upper reader and the lower reader have a dual free layer (DFL) MTJ structure between two shields. A synthetic antiferromagnetic (SAF) soft bias structure bounds the MTJ, and a rear hard bias (RHB) structure is disposed behind the MTJ. The DFL MTJ decreases the distance between the upper and lower reader and hence, improves the area density capacity (ADC). Additionally, the SAF soft bias structures and the rear head bias structure cause the dual free layer MTJ to have a scissor state magnetic moment at the media facing surface (MFS).

First claim

What is claimed is:

1. A two dimensional magnetic recording (TDMR) head, comprising:
a first reader including:
a first lower shield having a first width at a media facing surface;
a first seed layer disposed in contact with the first lower shield, the first seed layer having the first width at the media facing surface;
a first dual free layer (DFL) sensor disposed over the first lower shield comprising a first magnetic free layer and a second magnetic free layer, the first magnetic free layer of the first dual free layer sensor being disposed in contact with the first seed layer; and
a first upper shield layer disposed over and in contact with the first DFL sensor, the first upper shield layer being a single layer;

at least one first synthetic antiferromagnetic (SAF) structure disposed adjacent to the first DFL sensor, the at least one first SAF structure comprising a first lower soft bias layer, a first spacer layer disposed on the first lower soft bias layer, and a first upper soft bias layer disposed on the first spacer layer and in contact with the first upper shield layer;
an insulating reader separation gap disposed over the first reader, the insulating reader separation gap disposed in contact with the first upper shield layer; and
a second reader disposed over the insulating reader separation gap, the second reader including:
a second lower shield, the second lower shield being a single layer and having the first width at the media facing surface;
a second seed layer disposed in contact with the second lower shield, the second seed layer having the first width at the media facing surface;
a second DFL sensor disposed over the second lower shield, the second DFL sensor being aligned with the first DFL sensor at an air bearing surface, wherein a third magnetic free layer of the second DFL sensor is disposed in contact with the second seed layer; and
a second upper shield layer disposed over the second DFL sensor.

2. The TDMR head of claim 1 , wherein the first DFL sensor comprises:
the first magnetic free layer disposed on the first seed layer;
a first barrier layer disposed over the first magnetic free layer;
the second magnetic free layer disposed over the first barrier layer; and
a first capping layer disposed over the second magnetic free layer.

3. The TDMR head of claim 2 , wherein the second DFL sensor comprises:
the third magnetic free layer disposed over the second seed layer;
a second barrier layer disposed over the third magnetic free layer;
a fourth magnetic free layer disposed over the second barrier layer; and
a second capping layer disposed over the fourth magnetic free layer.

4. The TDMR head of claim 2 , wherein the first lower soft bias layer is disposed adjacent to a portion of the first magnetic free layer and a portion the first barrier layer, the first spacer layer is disposed adjacent to a portion of the first barrier layer and a portion of the second magnetic free layer, and the first upper soft bias layer is disposed adjacent to a portion of the second magnetic free layer and the first capping layer.

5. The TDMR head of claim 1 , further comprising a first rear hard bias structure disposed behind the first DFL sensor.

6. The TDMR head of claim 4 , further comprising a second rear hard bias structure disposed behind the second DFL sensor.

7. The TDMR head of claim 1 , further comprising at least one second SAF structure disposed adjacent the second DFL sensor.

8. A magnetic recording device comprising the TDMR head of claim 1 .

9. A two dimensional magnetic recording (TDMR) head, comprising:
a first reader including:
a first lower shield having a first width at a media facing surface;
a first seed layer disposed in contact with the first lower shield, the first seed layer having the first width at the media facing surface;
a first sensor disposed over the first lower shield, a first magnetic free layer of the first sensor being disposed in contact with the first seed layer;
a first upper shield layer disposed over and in contact with the first sensor; and
a first rear hard bias structure disposed behind the first sensor;

at least one first synthetic antiferromagnetic (SAF) structure disposed adjacent to the first sensor, the at least one first SAF structure comprising a first lower soft bias layer, a first spacer layer disposed on the first lower soft bias layer, and a first upper soft bias layer disposed on the first spacer layer and in contact with the first upper shield layer;
an insulating reader separation gap disposed over the first reader, the insulating reader separation gap disposed in contact with the first upper shield layer; and
a second reader disposed over the insulating reader separation gap, the second reader including:
a second lower shield, the second lower shield being a single layer and having the first width at the media facing surface;
a second seed layer disposed in contact with the second lower shield, the second seed layer having the first width at the media facing surface;
a second sensor disposed over the second lower shield, the second sensor being aligned with the first sensor at an air bearing surface, wherein a first magnetic free layer of the second sensor is disposed in contact with the second seed layer;
a second upper shield layer disposed over the second sensor, the second upper shield layer being a single layer; and
a second rear hard bias structure disposed behind the second sensor.

10. The TDMR head of claim 9 , wherein the first rear hard bias structure comprises CoPt.

11. The TDMR head of claim 9 , further comprising a first nonmagnetic layer disposed over the first rear hard bias structure.

12. The TDMR head of claim 9 , further comprising insulating material disposed between the first sensor and the first rear hard bias structure.

13. The TDMR head of claim 9 , wherein the first sensor and the second sensor do not include an antiferromagnetic layer.

14. The TDMR head of claim 9 , wherein the first lower shield has a first length from the media facing surface into the TDMR head, the first seed layer has the first length from the media facing surface into the TDMR head, the second lower shield has the first length from the media facing surface into the TDMR head, and the second seed layer has the first length from the media facing surface into the TDMR head.

15. A magnetic recording device comprising the TDMR head of claim 9 .

16. A two dimensional magnetic recording (TDMR) head, comprising:
a first reader including:
a first lower shield, the first lower shield being a single layer and having a first width at a media facing surface;
a first seed layer disposed in contact with the first lower shield, the first seed layer having the first width at the media facing surface;
a first sensor disposed over the first lower shield, a first magnetic free layer of the first sensor being disposed in contact with the first seed layer;
a first upper shield layer disposed over and in contact with the first sensor, the first upper shield layer being a single layer; and
a first synthetic antiferromagnetic (SAF) soft bias (SB) structure disposed adjacent the first sensor, the first SAF SB structure comprising a first lower soft bias layer, a first spacer layer disposed on the first lower soft bias layer, and a first upper soft bias layer disposed on the first spacer layer and in contact with the first upper shield layer;

an insulating reader separation gap disposed over the first reader, the insulating reader separation gap disposed in contact with the first upper shield layer; and
a se

Assignees

• Western Digital Tech Inc

Inventors

• Hu Chih-Ching
• Wang Yung-Hung
• Mao Ming
• Li Guanxiong
• Mauri Daniele
• Liu Xiaoyong
• Okada Yukimasa
• Roy Anup
• Chien Chen-Jung
• Liu Hongxue

Classifications

• G11B2005/3996

  large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices · CPC title

• G11B5/3909 Primary

  Arrangements using a magnetic tunnel junction · CPC title

• G11B5/3932

  Magnetic biasing films · CPC title

• G11B5/112

  Manufacture of shielding device · CPC title

• G11B5/23

  Gap features {(G11B5/1871, G11B5/1875, G11B5/265, G11B5/29, G11B5/488 and subgroups, G11B5/4907 and subgroups, G11B5/4969 and subgroups take precedence)} · CPC title