Toshiba Corp verified the efficacy of "3D magnetic recording," which increases the storage capacity of a hard disk drive (HDD) by using microwaves and a multilayer recording medium.

By using a microwave magnetic field, the orientation of the magnetization of a multilayer magnetic body was inverted for selected layers.

With this 3D magnetic recording, Toshiba aims to realize a recording density of 10 Tbits/inch2, which is about ten times higher than that of existing HDD products (about 1 Tbit/inch2). The company plans to apply the technology not only to HDDs but to magnetic memories and tapes.

Recording media (hard disks) are made by stacking magnetic layers having different "ferromagnetic resonance frequencies." When a microwave magnetic field with a frequency corresponding to the ferromagnetic resonance frequency is applied to a multilayer recording medium, it becomes possible to excite "magnetization oscillation" in a specific magnetic layer and reduce the amount of energy that the layer needs for "magnetization inversion" (microwave assist effect).

The microwave assist effect enables magnetization inversion with a selected recording layer for recording data. According to Toshiba, though the technology was confirmed in a simulation in the past, this is the first time that it has been verified. This time, the number of recording layers was two.

Toshiba plans to advance the development of "spin torque oscillation device," which enables to locally apply a microwave magnetic field, and develop a magnetic head on which the device can be mounted. In addition, the company will develop a recording medium suited for multilayer recording. With such efforts, it aims to realize 3D magnetic recording by about 2025.

The results of the research will be announced at ICM 2015, an international academic conference, which will take place from July 8, 2015, in Barcelona, Spain.