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The perturbative construction of the effective soft‐spin Hamiltonian of the system of magnetized nano‐loops
Author(s) -
Horváth D.,
Gmitra M.,
Baláž P.
Publication year - 2004
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200402084
Subject(s) - physics , hamiltonian (control theory) , spins , zeeman effect , toroid , quantum electrodynamics , excited state , vorticity , quantum mechanics , classical mechanics , condensed matter physics , magnetic field , vortex , plasma , mechanics , mathematics , mathematical optimization
The effective large‐scale Hamiltonian of a planar system of nano‐loops in a weakly excited flux‐closed magnetized state has been constructed by means of a perturbative technique based on micromagnetic theory. The Hamiltonian is written by means of two classes of collective variables: the continuous soft spins and discrete vorticity charges. Analytical and numerical calculations of the inter‐loop magnetostatic energy are compared for a pair of magnetic nano‐loops. The transformation from small‐scale to collective variables is performed for intra‐loop exchange‐coupling, magnetostatic and Zeeman energy terms. Evidence of correlations of uniform vortex charges in low‐energy configurations is uncovered numerically. The generalization of the perturbative method that deals with more realistic out‐of‐plane excitations is also considered. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)