Fizika Nizkikh Temperatur: Volume 31, Number 8-9 (August 2005), p. 1042-1058    ( to contents , go back )

Magnetoelasticity and domain structure in antiferromagnetic crystals of an iron-group dihalides

V.M. Kalita, A.F. Lozenko, S.M. Ryabchenko, and P.A. Trotsenko

Institute of Physics of the National Academy of Sciences 46 Nauki Ave., Kiev 03028, Ukraine
E-mail: lozenko@iop.kiev.ua
pos Анотація:

Received December 31, 2004, revised May 4, 2005

Abstract

Formation of the antiferromagnetic magnetoelastic domains in the easy-plane antiferromagnets of an iron-group dihalides in which the infinite- fold degeneracy of the spatial orientation of an antiferromagnetizm vector L in a easy plane is removed due to spontaneous magnetostriction is investigated. Domains in considered crystals differ from each other not only directions of a vector L but also a directions of the main axes of spontaneous magnetostriction deformations, connected to the L. Thus the system of antiferromagnetic domains appears to identical system of elastic domains. It is shown that processes of magnetization and striction, which are forced by magnetic field in a multidomain antiferromagnetic state, are interconnected. The data of the forced magnetostriction field dependences in a multidomain state of the easy-plane antiferromagnets CoCl2 and NiCl2 are given and analyzed. It is shown that though magnetostriction in cycles of introducing– deducing of a magnetic field includes both the convertible and irreversible contributions, the main component is convertible one. It is shown that only domains with magnetoelastic striction are responsible for convertibility (equilibrium) of a multidomain state. The description of the magnetostriction field dependencies of homogeneous and multidomain states and also the behavior of magnetization of crystals in a magnetic field are carried out. For the description of rearrangement of a multidomain state the approximation of the continuous distribution of domains on orientations of their L vector in the easy plane of a crystal in absence of an external magnetic field is used. It is shown that the coordination of elastic fields of domain system and elastic fields of defects is capable to provide formation of a convertible multidomain state, that is to make this state energetically favourable. Results of consideration are well matched to experimental data.

PACS:
75.50.Ee - Antiferromagnetics
75.60.Ej - Magnetization curves, hysteresis, Barkhausen and related effects
75.80. -
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