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Title: Temperature effect on vortex-core reversals in magnetic nanodots

We studied the temperature effect on vortex-core reversals in soft magnetic nanodots by micromagnetic numerical calculations within a framework of the stochastic Landau-Lifshitz-Gilbert scheme. It was determined that vortex-core-switching events at non-zero temperatures occur stochastically, and that the threshold field strength increases with temperature for a given field frequency. The mechanism of core reversals at elevated temperatures is the same as that of vortex-antivortex-pair-mediated core reversals found at the zero temperature. The reversal criterion is also the out-of-plane component of a magnetization dip that should reach −p, which is to say, m{sub z,dip} = −p, where p is the original polarization, p = +1 (−1), for the upward (downward) core. By this criterion, the creation of a vortex-antivortex pair accompanies complete vortex-antivortex-annihilation-mediated core reversals, resulting in the maximum excess of the exchange energy density, ΔE{sub ex}{sup cri} ≈ 15.4 ± 0.2 mJ/cm{sup 3}. This work provides the underlying physics of vortex-core reversals at non-zero temperatures, and potentiates the real application of vortex random access memory operating at elevated temperatures.
Authors:
; ; ;  [1]
  1. Department of Materials Science and Engineering, National Creative Research Initiative Center for Spin Dynamics and Spin-Wave Devices, Nanospinics Laboratory, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22402981
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANNIHILATION; ENERGY DENSITY; MAGNETIC FIELD REVERSAL; MAGNETIC MATERIALS; MAGNETIZATION; POLARIZATION; QUANTUM DOTS; RANDOMNESS; STOCHASTIC PROCESSES; TEMPERATURE DEPENDENCE; VORTICES