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Title: Noise-induced bifurcations in magnetization dynamics of uniaxial nanomagnets

Stochastic magnetization dynamics in uniformly magnetized nanomagnets is considered. The system is assumed to have rotational symmetry as the anisotropy axis, the applied field, and the spin polarization are all aligned along an axis of symmetry. By appropriate integration of the Fokker-Planck equation associated to the problem, the stochastic differential equation governing the evolution of the angle between the magnetization orientation and the symmetry axis is derived. The drift terms present in this equation contain a noise-induced drift term, which, in combination with drift terms of deterministic origin, can be written as the derivative of an effective potential. Superparamagnetic-like transitions are studied in connections with the bifurcations of the effective potential as temperature and excitation conditions are varied.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Dipartimento di Ingegneria Elettrica e delle Tecnologie dell'Informazione, Università di Napoli “Federico II,” I-80125 Napoli (Italy)
  2. Istituto Nazionale di Ricerca Metrologica, I-10135 Torino (Italy)
  3. Dipartimento di Ingegneria, Università di Napoli “Parthenope,” I-80143 Napoli (Italy)
  4. ECE Department and UMIACS, University of Maryland, College Park, Maryland 20742 (United States)
Publication Date:
OSTI Identifier:
22403041
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; ANISOTROPY; EXCITATION; FOKKER-PLANCK EQUATION; MAGNETIC MATERIALS; MAGNETIZATION; MAGNETS; POTENTIALS; SPIN ORIENTATION; STOCHASTIC PROCESSES; SUPERPARAMAGNETISM; TEMPERATURE DEPENDENCE