IEEE S.F. Bay Area Council e-GRID's
BayAreaTech

TUESDAY September 18, 2012
SCV Magnetics Chapter
Speaker: Dr Mike Mallary, Western Digital Corp.
Time: Networking and pizza at 7:00 PM; Presentation at 7:30 PM
Cost: none
Place: Western Digital, 1710 Automation Parkway, San Jose
RSVP: not required
Web: ewh.ieee.org/r6/scv/mag

Perpendicular Magnetic Recording, PMR, will soon reach its superparamagnetic limit. Shingling the write process will allow significant increases in areal density but with significant system complexity and performance issues in some applications.? At this time, Heat Assisted Magnetic Recording and Bit Patterned Media are the primary candidates to replace PMR.? However there are significant concerns associated with these approaches.? The economics of BPM are a considerable barrier by most estimates.? The high temperatures of HAMR are a serious reliability concern and perfecting FePt media is very challenging.? Even though MAMR is not expected to extend areal density as far as these other alternatives, its implementation would require smaller changes from PMR.? Therefore MAMR may be able to sustain areal density growth while these alternate technologies are being perfected.? But can MAMR be made to work well enough?
At this time there are no published demonstrations of MAMR at high densities.? However, there are a number of reported observations of partial and full switching of PMR like media with moderate DC fields assisted by rf fields from micro-loops or a Spin Torque Oscillator (STO).? These results will be discussed along with the results of simulations and experiments by the author.? Micromagnetic simulations of the MAMR write process indicate that MAMR could approximately double recording density beyond the limits of PMR on optimized media.? The system studied was that of a STO in the write gap of a wide track shielded pole PMR like head as originally proposed and patented by Prof. Jimmy Zhu of the Data Storage System Center at Carnegie Mellon University.? Micromagnetic simulations of the MAMR write process, M-H loops with rf fields, Ferromagnetic Resonance of media, and STOs will be presented. In addition, some experimental results on media FMR and STO performance will be discussed.