Microwave-assisted recording technology promises

By | April 29, 2021

Researchers at Toshiba Corporation in Japan have studied the operation of a small device built into the writing interval of the right head of a hard disk drive to increase its recording density. The device, developed by HWY Technologies, is based on a design concept known as microwave-assisted magnetic recording or MAMR.

This technique, reported in the Journal of Applied Physics, uses a microwave field generator known as a spin-torque oscillator. The spin-torque oscillator emits a microwave field that causes the magnetic particles of the recording medium to rotate the way a spinning top does. This makes them much easier when the writing head applies a recording magnetic field in the writing process.

In a computer hard drive, each bit of data is stored in magnetic particles known as grains. The magnetic orientation of the grain determines whether the bit is 0 or 1.

Making the grains smaller allows them to pack more tightly together. This increases storage capacity, but also makes data bits unstable. The development of MAMR allows the use of more stable magnetic materials, but also limits the type of recording media that can be developed.

The investigators focused on another effect known as the flux control (FC) effect, which also occurs in MAMR. This effect improves the recording area and is maximized when the magnetization interval of the spin torque oscillator is completely reversed against the field.

The advantage of the FC effect, according to the author Hirofumi Suto, is that any magnetic recording achieves improvement. This is important, as it will no longer be necessary to use specially designed recording media for the MAMR technique.

The FC device, a type of spin-torque oscillator designed to maximize the FC effect, consists of two magnetic layers written directly into the gap of the writing head. A bias current supplied to the device reverses the magnetization of one of the layers through an effect known as spin-transfer torque.

The investigators experimented with different bias currents and found that magnetization reversal occurred more rapidly at higher currents. Computing his experiments with a computational model, he also determined that the recording area was increased by the FC effect, improving the writing ability of the writing head and surpassing the performance of traditional writing heads.

According to the SCO, the FC device operates effectively at a fast write rate of about 3 gigabits per second. These results provide evidence that FC devices work by design and suggest that FC-MAMR is a promising technique to increase the regional density of hard disk drives.

Toshiba plans to introduce hard disk drives using MAMR technology that will increase hard disk capacity by 16–18 terabytes.

This technique uses a microwave field generator known as a spin-torque oscillator, reported in the Journal of Applied Physics by AIP Publishing. The spin-torque oscillator emits a microwave field that causes the magnetic particles of the recording medium to rotate the way a spinning top does.

This makes them much easier when the writing head applies a recording magnetic field in the writing process.

In a computer hard drive, each bit of data is stored in magnetic particles known as grains. The magnetic orientation of the grain determines whether the bit is 0 or 1.

Making the grains smaller allows them to pack more tightly together. This increases storage capacity, but also makes data bits unstable. The development of MAMR allows the use of more stable magnetic materials, but also limits the type of recording media that can be developed.

The investigators focused on another effect known as the flux control (FC) effect, which also occurs in MAMR. This effect improves the recording area and is maximized when the magnetization interval of the spin torque oscillator is completely reversed against the field.

The advantage of the FC effect, according to the author Hirofumi Suto, is that any magnetic recording achieves improvement. This is important, as it will no longer be necessary to use specially designed recording media for the MAMR technique.

The FC device, a type of spin-torque oscillator designed to maximize the FC effect, consists of two magnetic layers written directly into the gap of the writing head. A bias current supplied to the device reverses the magnetization of one of the layers through an effect known as spin-transfer torque.

The investigators experimented with different bias currents and found that magnetization reversal occurred more rapidly at higher currents. Computing his experiments with a computational model, he also determined that the recording area was enhanced by the FC effect.