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Title

Resonant quantum coherence of magnetization at excited states in nanospin systems with different crystal symmetries

Author(s)

Zhu, Jia-Lin;  Lu, Rong;  Kou, Su-Peng;  Hu, Hui;  Gu, Bing-Lin

Abstract

The quantum interference effects induced by the Wess-Zumino term, or Berry phase are studied theoretically in resonant quantum coherence of the magnetization vector between degenerate states in nanometer-scale single-domain ferromagnets in the absence of an external magnetic field. We consider the magnetocrystalline anisotropy with trigonal, tetragonal and hexagonal crystal symmetry, respectively. By applying the periodic instanton method in the spin-coherent-state path integral, we evaluate the low-lying tunnel splittings between degenerate excited states of neighboring wells. And the low-lying energy level spectrum of mth excited state are obtained with the help of the Bloch theorem in one-dimensional periodic potential. The energy level spectrum and the thermodynamic properties of magnetic tunneling states are found to depend significantly on the total spins of ferromagnets at sufficiently low temperatures. Possible relevance to experiments is also discussed.

Publication type

Journal article

Source

European Physical Journal B: Condensed Matter and Complex Systems, Vol. 16, no. 3 (Aug 2000), pp. 507-513

Publication year

2000

FOR Code(s)

01 Mathematical Sciences;  02 Physical Sciences

Keyword(s)

Macroscopic quantum phenomena;  Magnetic systems;  Measurement theory;  Quantised spin models

Publisher

EDP Sciences and Springer

ISSN

1434-6028

Publisher URL

http://dx.doi.org/10.1007/s100510070210

Copyright

Copyright © EDP Sciences, Societa Italiana di Fisica, Springer-Verlag 2000. Accepted manuscript of the paper reproduced here in accordance with the copyright policies of the joint publishers.

Full text

Peer reviewed