We report an experimental study on the dynamic thermomagnetic (TM) reversal mechanisms at
around Curie temperature (Tc) for isolated 60nm pitch single-domain [Co/Pd] islands heated by a
1.5 lm spot size laser pulse under an applied magnetic reversal field (Hr). Magnetic force microscopy
(MFM) observations with high resolution MFM tips clearly showed randomly trapped nonswitched
islands within the laser irradiated spot after dynamic TM reversal process with insufficient
Hr strength. This observation provides direct experimental evidence by MFM of a large magnetization
switching variation due to increased thermal fluctuation/agitation over magnetization energy at
the elevated temperature of around Tc. The average percentage of non-switched islands/magnetization
was further found to be inversely proportional to the applied reversal field Hr for incomplete
magnetization reversal when Hr is less than 13% of the island coercivity (Hc), showing an increased
switching field distribution (SFD) at elevated temperature of around Tc (where main contributions
to SFD broadening are from Tc distribution and stronger thermal fluctuations). Our experimental
study and results provide better understanding and insight on practical heat assisted magnetic recording
(HAMR) process and recording performance, including HAMR writing magnetization dynamics
induced SFD as well as associated DC saturation noise that limits areal density, as were previously
observed and investigated by theoretical simulations
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Copyright (2014) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters 105, 162402 (2014) and may be found at http://dx.doi.org/10.1063/1.4899135.