A study on dynamic heat assisted magnetization reversal mechanisms under insufficient reversal field conditions

Journal Article · Mon Oct 20 00:00:00 EDT 2014 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4899135· OSTI ID:22350957

Chen, Y. J.; Yang, H. Z.; Leong, S. H.; Yu Ko, Hnin Yu ^[1]; Wu, B. L.; Ng, V. ^[2]; Asbahi, M.; Yang, J. K. W. ^[3]

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1. Data Storage Institute, Agency for Science, Technology and Research (A-Star), 5 Engineering Drive 1, Singapore 117608 (Singapore)
2. Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore)
3. Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-Star), 3 Research Link, Singapore 117602 (Singapore)

We report an experimental study on the dynamic thermomagnetic (TM) reversal mechanisms at around Curie temperature (Tc) for isolated 60 nm pitch single-domain [Co/Pd] islands heated by a 1.5 μm 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 non-switched 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.

• OSTI ID: 22350957
• Journal Information: Applied Physics Letters, Vol. 105, Issue 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOMIC FORCE MICROSCOPY
COERCIVE FORCE
CURIE POINT
DENSITY
DISTRIBUTION
FLUCTUATIONS
IRRADIATION
LASER RADIATION
LASER-RADIATION HEATING
MAGNETIC FIELDS
MAGNETIC PROPERTIES
MAGNETIZATION
NOISE
RANDOMNESS
RESOLUTION
SATURATION
SIMULATION
SWITCHES
TRAPPING