Microwave assisted magnetic Recording: Physics and application to hard disk drives

Microwave assisted magnetic recording (MAMR) is one of the key candidate technologies for ten terabits class magnetic recording. In this article, we review MAMR technology and its application to hard disk drives (HDDs) with related recording physics. The physical principles of MAMR are based on the microwave assisted switching (MAS) effect and the spin transfer switching (STS) effect. In addition to reviewing these effects, the key points for applying MAMR technologies to HDDs are explained using the concept of effective magnetic write fields (effective write field), which is often used to explain the recording capabilities of magnetic recording technology. Although effective write field studies have revealed several difficulties with MAMR, these studies have also proposed several measures for handling them. The MAS effect is observed in many experiments and effective write field studies indicate high potential for application to HDDs. Many simulation studies have obtained a high signal-to-noise ratio (SNR) gain. Optimizing head-media integration is a key issue for application according to these studies.