Microwave-Assisted switching in CoCrPt granular medium under continuous microwave fields

Nobuaki Kikuchi, Katsunari Sato, Shun Kikuchi, Satoshi Okamoto, Takehito Shimatsu, Osamu Kitakami, Hitoshi Osawa, Motohiro Suzuki

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


We have fabricated a device for microwave-Assisted switching (MAS) experiments with perpendicularly magnetized CoCrPt-SiO2 granular film with anisotropy field Hk = 18.8 kOe. The device was carefully designed to be able to apply a microwave field of 0.95 kOe in amplitude continuously, allowing direct evaluation of microwave-Assisted switching properties of the medium without any assumptions about time-dependent switching behavior. The coercivity of CoCrPt-SiO2 medium linearly decreases with increasing microwave frequency, and the maximum coercivity reduction ratio reaches 80% for hrf = 0.95 kOe at frf = 25 GHz after subtracting the effect of temperature rise due to microwave field application. The linear slope of coercivity against the frequency becomes steeper with increasing microwave field amplitude, which is a unique frequency and amplitude dependencies in granular media. Correlation length obtained by X-ray magnetic circular dichroism microscopy measurement decreases by applying a microwave field with higher frequency, suggesting that the magnetic clustering dimensions of the medium possibly depend on microwave frequency during microwave-Assisted switching.

Original languageEnglish
Article number083908
JournalJournal of Applied Physics
Issue number8
Publication statusPublished - 2019 Aug 28

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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