Tuesday, September 18th, 2012
Western Digital, 1710 Automation Parkway, San Jose, CA
Directions and Map
Cookies, Conversation &
Pizza too at 7:00 P.M.
Presentation at 7:30 P.M.
Microwave Assisted Magnetic Recording
Dr Mike Mallary
Western Digital Corp.
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
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.
Dr Mike Mallary received the S.B. degree in physics from the
Massachusetts Institute of Technology, Cambridge, in 1966, and the Ph.D.
degree in Experimental High Energy Physic from the California Institute of
Technology, in 1971.
He was a post doctoral
fellow at the Rutherford Laboratory for from 1972-1974 and an Assistant
Professor of physics at Northeastern University from 1974-1978. There he
participated in an experiment at Fermi Laboratory that produced early
evidence for the fifth quark using a 300 ton solid iron magnet. From 1978
to 1980 he worked at the Magnetic Corporation of America designing large
In 1980 he
joined the Digital Equipment Corporations effort to produce thin film
heads for disk drive recording as a head modeler and designer. Here he
invented the Shielded Pole perpendicular recording head which has
demonstrated superior performance over the conventional monopole head and
is presently in all shipped disk drives. He also invented the Diamond
inductive head which doubles the effective number of turns and contributed
to the theory of flux conduction in thin film heads.
Through a series of acquisitions beginning in
1992, Dr Mallary worked for Quantum, MKQC, Maxtor, and Seagate. He is
presently a Senior Technologist with Western Digital Corporation. He has
authored and co-authored 92 issued U.S. patents (140 total) and 52
publications. He is an IEEE Fellow and was an IEEE Distinguished
Lecturer in 2009.
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