Role of Media Parameters in Switching Granular Perpendicular Media Using Microwave Assisted Magnetic Recording

• Published in: IEEE transactions on magnetics Vol. 45; no. 2; pp. 889 - 892
• Main Authors: Batra, S., Scholz, W.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.02.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Anisotropic magnetoresistance; Cross-disciplinary physics: materials science; rheology; Damping; Demagnetization; Direct current; Exact sciences and technology; Landau-Lifshitz-Gilbert equation; Magnetic materials; Magnetic recording; Magnetic switching; Magnetism; Magnetization; Materials science; Mathematical analysis; Mathematical models; Media; Micromagnetics; Other topics in materials science; Physics; Radio frequencies; Radio frequency; Reduction; relaxation mechanism; RF assisted switching; Switches; Switching; switching field; Temperature distribution; Damping; switching field; Microwave radiation; Landau-Lifshitz-Gilbert equation; RF assisted switching; Switching; Mechanism; Magnetic recording; Magnetic properties; relaxation mechanism
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2008.2010669

This paper describes the role of media parameters in magnetization switching in the presence of a DC bias and an in-plane RF field using a micromagnetic model. In this study, two sets of media parameters are compared for reduction in switching field based on the Larmor precessional frequency of the medium. It is found that a significant reduction in equivalent Stoner Wohlfarth (SW) field (H SW E ) is observed only when a DC field is applied at a finite angle relative to the medium anisotropy direction (thetas A ) and we observe a shallow minimum between 20deg and 30deg. A small field magnitude H SW E ( = 0.50 H K ) for thetas A of 20deg for medium 1 using an RF field magnitude of 0.068 H K and an even smaller magnitude H SW E (=0.22 H K ) for thetas A of 25degfor medium 2 using an RF field magnitude of 0.035 H K is required to switch the media for the case of a uniform granular medium without any distributions at T = 0 K. With the inclusion of magnetic materials distributions and/or introducing finite temperature, the coherent precession is lost due to the demagnetization field of neighboring grains. We compare H SW E required to switch the medium in the presence of RF assist to the SW field (H SW ) required to switch the medium when there is no assist field. It is found that medium 1 shows a reduction of 28% in SW field while medium 2 shows no reduction in presence of in-plane RF field compared to the case when no RF field is applied. This highlights the importance of medium properties in microwave-assisted magnetic recording. Selection of media parameters will depend on the potential application of microwave-assisted recording in a continuous granular or the bit patterned media.