# US 2019/0378541 A1 · Microwave assisted magnetic recording drive utilizing interlaced track recording

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- Number: US 2019/0378541 A1
- Document ID: US20190378541A1
- Status: Published application
- Kind: A1
- Application number: 16/506,222
- Filed: 2019-07-09
- Published: 2019-12-12
- Earliest claimed: 2018-06-12
- Assignees: Seagate Technology LLC
- Applicants: Seagate Technology LLC
- Inventors: Steven Douglas Granz; Mehmet Fatih Erden
- Web page: https://patentgrep.com/patent/US20190378541A1

## CPC

- G11B 20/1217: {on discs}
- G11B 5/012: Recording on, or reproducing or erasing from, magnetic disks (G11B17/00, G11B19/00 take precedence)
- G11B 2005/0024: {Microwave assisted recording}
- G11B 2020/1238: {track, i.e. the entire a spirally or concentrically arranged path on which the recording marks are located}
- G11B 2020/1292: {Enhancement of the total storage capacity}
- 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

Bottom tracks are written to a recording medium using a first setting of a spin-torque oscillator of a single microwave assisted magnetic recording (MAMR) head. Top tracks are written interlaced between and partially overlapping the bottom tracks using the single MAMR head at a second setting of the MAMR head, the first and second settings resulting in different bit aspect ratios for the top and bottom tracks.

## Claims

### Claim at position 1

1-20. (canceled)

### Claim 21

A method, comprising:
writing bottom tracks to a recording medium using a first setting of a spin-torque oscillator of a single microwave assisted magnetic recording (MAMR) head;
writing top tracks interlaced between and partially overlapping the bottom tracks using the single MAMR head at a second setting of the spin-torque oscillator, the first and second settings resulting in different bit aspect ratios for the top and bottom tracks.

### Claim 22 (depends on 21)

The method of claim 21, wherein the first and second settings comprise first and second microwave powers of the spin-torque oscillator.

### Claim 23 (depends on 21)

The method of claim 21, wherein for one of the first and second settings, no power is applied to the spin-torque oscillator—and for another of the first and second settings a non-zero power is applied to the spin-torque oscillator.

### Claim 24 (depends on 21)

The method of claim 21, wherein the first and second settings comprise first and second different combinations of spin-torque oscillator power and spin-torque oscillator frequency.

### Claim 25 (depends on 21)

The method of claim 21, wherein the bottom and top tracks are written at different track widths.

### Claim 26 (depends on 21)

The method of claim 21, wherein the bottom and top tracks are written at different linear bit densities.

### Claim 27 (depends on 21)

The method of claim 21, wherein the bottom tracks are assigned to a first logical group and the top tracks are assigned to a second logical band, tracks within the first and second logical bands being treated as adjacent tracks during reading and writing.

### Claim 28 (depends on 21)

The method of claim 21, further comprising, before writing the top and bottom tracks, performing a procedure to determine a target linear bit density of the bottom tracks, the procedure comprising:
writing first bottom test tracks at increasing linear bit densities until a maximum allowable bit error rate is measured;
determining a maximum linear bit density associated with the maximum allowable bit error rate;
starting with the maximum linear bit density, writing second bottom test tracks at decreasing linear bit densities until a threshold bit error rate is determined; and
setting the target linear bit density of the bottom tracks based on a linear bit density corresponding to the threshold bit error rate.

### Claim 29 (depends on 28)

The method of claim 28, wherein the procedure further comprises:
writing top test tracks at increasing linear bit densities until a second maximum bit error rate is measured at a target linear bit density of the top tracks;
if writing the top tracks at the target linear bit density partially overlapping the bottom tracks does not increase the threshold bit error rate of the bottom tracks beyond a threshold, using the target linear bit density of the top tracks to write the top tracks, otherwise using a reduced linear bit density less than for one of the top and bottom tracks.

### Claim 30

An apparatus, comprising:
interface circuitry operable to control a spin-torque oscillator of a single microwave assisted magnetic recording (MAMR) head; and
a controller coupled to the interface circuitry, the controller configured to:
write bottom tracks to a recording medium of the apparatus using the single MAMR head at a first setting of the spin-torque oscillator;
write top tracks interlaced between and partially overlapping the bottom tracks using the single MAMR head at a second setting of the spin-torque oscillator, the first and second settings resulting in different bit aspect ratios for the top and bottom tracks.

### Claim 31 (depends on 30)

The apparatus of claim 30, wherein the first and second settings comprise first and second microwave powers of the spin-torque oscillator.

### Claim 32 (depends on 30)

The apparatus of claim 30, wherein for one of the first and second settings, no power is applied to the spin torque oscillator and for another of the first and second settings a non-zero power is applied to the spin-torque oscillator.

### Claim 33 (depends on 30)

The apparatus of claim 30, wherein the first and second settings comprise first and second different combinations of spin-torque oscillator power and spin-torque oscillator frequency.

### Claim 34 (depends on 30)

The apparatus of claim 30, wherein the bottom and top tracks are written at different track widths.

### Claim 35 (depends on 30)

The apparatus of claim 30, wherein the bottom and top tracks are written at different linear bit densities.

### Claim 36 (depends on 30)

The apparatus of claim 30, wherein the bottom tracks are assigned to a first logical group and the top tracks are assigned to a second logical band, tracks within the first and second logical bands being treated as adjacent tracks during reading and writing.

### Claim 37

A method, comprising:
writing first bottom test tracks to a recording medium at a first setting of a spin-torque oscillator of a single microwave assisted magnetic recording (MAMR), linear bit densities of the first bottom tracks increased until a maximum allowable bit error rate is measured at a maximum linear bit density;
starting with the maximum linear bit density, writing second bottom test tracks using the single MAMR head at the first setting, linear bit densities of the second bottom test tracks increased until a threshold bit error rate is determined corresponding to an operational bottom track linear bit density;
writing top test tracks using the single MAMR head at a second setting of the spin torque oscillator over third bottom test tracks written at the operational bottom track linear bit density, linear bit densities of the top test tracks increased until a second maximum bit error rate is measured at an operational top track linear bit density; and
using the operational bottom and top linear bit densities to record respective interleaved top and bottom operational tracks using the single MAMR head.

### Claim 38 (depends on 37)

The method of claim 37, further comprising, if writing the top test tracks at the operational top track linear bit density over the third bottom test tracks increases a bit error rate of the bottom test tracks past the threshold bit error rate plus a delta, reducing the operational bottom track linear bit density.

### Claim 39 (depends on 37)

The method of claim 37, further comprising, if writing the top test tracks at the operational top track linear bit density over the third bottom test tracks increases a bit error rate of the bottom test tracks past the threshold bit error rate plus a delta, reducing the operational top track linear bit density.

### Claim 40 (depends on 37)

The method of claim 37, further comprising, if writing the top test tracks at the operational top track linear bit density over the third bottom test tracks increases a bit error rate of the bottom test tracks past the threshold bit error rate plus a delta, decreasing a track width of the top operational tracks.