# US 7,609,478 B2 · Magnetic writer pole with a graded magnetic moment

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- Number: US 7,609,478 B2
- Document ID: US7609478B2
- Status: Granted
- Kind: B2
- Application number: 11/390,681
- Filed: 2006-03-28
- Published: 2007-10-04
- Granted: 2009-10-27
- Earliest claimed: 2006-03-28
- Assignees: Seagate Technology LLC
- Inventors: Dehua Han; Xuefei Tang; Christopher James Thompson Rea; Jianhua Xue
- Web page: https://patentgrep.com/patent/US7609478B2

## CPC

- G11B 5/1278: {specially adapted for magnetisations perpendicular to the surface of the record carrier}
- 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 magnetic writer includes a write pole configured to reduce a skew effect during writing to a magnetic medium. A trailing portion of the write pole has a magnetic moment greater than a leading portion of the write pole.

## Claims

### Claim 1

A magnetic writer comprising a multilayer write pole configured to reduce a skew effect during writing to a magnetic medium, the write pole comprising alternating magnetic and nonmagnetic layers, wherein magnetization directions of adjacent magnetic layers of the write pole are antiparallel and each of the magnetic layers of the write pole has a different magnetic moment, the magnetic layers having increasing magnetic moments from a leading edge of the write pole to a trailing edge of the write pole, such that a trailing portion of the write pole has a magnetic moment greater than a leading portion of the write pole and an intermediate portion of the write pole between the trailing portion and the leading portion has a magnetic moment greater than the leading portion and less than the trailing portion.

### Claim 2 (depends on 1)

The magnetic writer of claim 1, wherein a trailing edge of the write pole is wider than a leading edge of the write pole.

### Claim 3 (depends on 2)

The magnetic writer of claim 2, wherein the leading edge and the trailing edge define a physical wall angle in the range of about 0° to about 20°.

### Claim 4 (depends on 3)

The magnetic writer of claim 3, wherein an effective wall angle of the write pole is greater than the physical wall angle of the write pole.

### Claim 5 (depends on 1)

The magnetic writer of claim 1, wherein the write pole has a substantially trapezoidal cross-section.

### Claim 6 (depends on 1)

The magnetic writer of claim 1, wherein each of the leading portion and the trailing portion of the write pole comprises four magnetic layers alternating with nonmagnetic layers.

### Claim 7

A multilayer write pole comprising:
a leading portion comprising alternating magnetic and nonmagnetic layers, the leading portion having a leading edge with a first magnetic moment and a first width;
a trailing portion comprising alternating magnetic and nonmagnetic layers, the trailing portion having a trailing edge with a second magnetic moment greater than the first magnetic moment and a second width greater than the first width; and
an intermediate portion between the leading portion and the trailing portion, the intermediate portion having a third magnetic moment greater than the first magnetic moment and less than the second magnetic moment;
wherein magnetization directions of adjacent magnetic layers of the multilaver write pole are antiparallel and each of the magnetic layers has a different magnetic moment, such that the magnetic layers have increasing magnetic moments from the leading edge to the trailing edge of the multilayer write pole.

### Claim 8 (depends on 7)

The multilayer write pole of claim 7, wherein the leading edge and the trailing edge of the multilayer write pole define a physical wall angle in the range of about 0° to about 20°.

### Claim 9 (depends on 8)

The multilayer write pole of claim 8, wherein an effective wall angle of the multilayer write pole is greater than the physical wall angle of the multilayer write pole.

### Claim 10 (depends on 7)

The multilayer write pole of claim 7, wherein each of the leading portion and the trailing portion comprises four magnetic layers alternating with nonmagnetic layers.

### Claim 11 (depends on 10)

The multilayer write pole of claim 10, wherein the intermediate portion comprises four magnetic layers alternating with nonmagnetic layers.

### Claim 12

A perpendicular magnetic writer comprising a main pole including a main pole tip having a substantially trapezoidal effective cross-section, wherein the main pole tip is a multilayer structure comprising alternating layers of magnetic and nonmagnetic materials and having a trailing region, a leading region, and an intermediate region between the trailing region and the leading region, wherein magnetization directions of adjacent layers of the magnetic materials in the main pole tip are antiparallel and each of the layers of the magnetic materials in the main pole tip has a different magnetic moment, the layers of the magnetic materials having increasing magnetic moments from a leading edge of the main pole tip to a trailing edge of the main pole tip, such that the trailing region of the main pole tip has a greater magnetic moment than the leading region of the main pole tip and wherein the intermediate region of the main pole tip has a lesser magnetic moment than the trailing region of the main pole tip and a greater magnetic moment than the leading region of the main pole tip; wherein the leading edge and the trailing edge of the main pole tip define a physical wall angle in the range of about 0° to about 20° and an effective wall angle of the main pole tip is greater than the physical wall angle of the main pole tip.