Multilayer recording for HDDs
Research at Toshiba has provided a reliable method in which to utilise microwave magnetic fields to reverse magnetization directions by selecting layers in a multilayer magnetic medium. This technology is expected to allow for increased capacity of hard disk drives by adopting high-density, multilayer (three-dimensional) magnetic recording media.
The method employed work by stacking magnetic layers with different ferromagnetic resonance frequencies and applying a microwave field having a frequency corresponding to an appropriate ferromagnetic resonance.
it is possible to excite a magnetization oscillation in only a specific magnetic layer. Magnetization reversal becomes possible in oscillation-excited layers, because the energy required for the magnetization reversal is reduced through a microwave assistance effect. While this technology has been previously predicted through simulation, this experiment represents its first realization. The magnetic reversal technology the researchers have demonstrated is a fundamental technology for magnetic recording, and can be applied to the multilayering (three-dimensional construction) of recording layers in HDDs, magnetic memory, magnetic tapes, and other high-density magnetic recording products.