# US 5,344,669 A · Method of manufacture for an improved magnetoresistive read transducer

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- Number: US 5,344,669 A
- Document ID: US5344669A
- Status: Granted
- Kind: A
- Application number: 08/125,987
- Filed: 1993-09-23
- Granted: 1994-09-06
- Earliest claimed: 1991-10-18
- Assignees: International Business Machines Corporation
- Inventors: Mao-Min Chen; Ching H. Tsang
- Web page: https://patentgrep.com/patent/US5344669A

## CPC

- G11B 5/399: {with intrinsic biasing, e.g. provided by equipotential strips}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

A magnetoresistive (MR) read transducer in which a layered structure comprising an MR layer, an antiferromagnetic material in direct contact with the MR layer and a thin layer of interdiffusion material in contact with the layer of antiferromagnetic material is subjected to a heating process to a temperature within a chosen temperature for a chosen time to form a magnetic interface between the antiferromagnetic material the MR layer. The magnetic interface produces a high level of exchange bias with the MR layer.

## Claims

### Claim 1

A method for making a magnetoresistive read transducer assembly comprising the steps of:
providing a substrate;
depositing a thin magnetoresistive layer of ferromagnetic material on said substrate;
depositing a thin layer of antiferromagnetic material in direct contact with the magnetoresistive layer;
depositing a thin layer of an interdiffusion material in contact with the layer of antiferromagnetic material; and
heating said layered structure to form a magnetic interface between said antiferromagnetic material and said magnetoresistive layer whereby said magnetic interface produces an exchange bias field in said magnetoresistive layer.

### Claim 2 (depends on 1)

The method of claim 1 wherein said interdiffusion material comprises a noble metal.

### Claim 3 (depends on 2)

The method of claim 2 wherein said noble metal is taken from the group consisting of gold, rhodium, platinum, palladium, and ruthenium.

### Claim 4 (depends on 1)

The method of claim 1 wherein said magnetoresistive layer comprises an alloy of nickel and iron and said antiferromagnetic layer comprises an alloy of iron and manganese.

### Claim 5 (depends on 4)

The method of claim 4 wherein said interdiffusion material comprises a noble metal.

### Claim 6 (depends on 5)

The method of claim 5 wherein said noble metal is taken from the group consisting of gold, rhodium, platinum, and palladium, and ruthenium.

### Claim 7 (depends on 6)

The method of claim 6 wherein said noble metal is gold.

### Claim 8 (depends on 7)

The method of claim 7 wherein said heating step is conducted at a temperature within the range of about 220.degree. to 320.degree. C. for a time within the range of about 2 to 12 hours.

### Claim 9 (depends on 8)

The method of claim 8 wherein said heating step is conducted at a temperature of about 240.degree. C. for a time of about 7 hours.