The physics of magnetic domains
V. G. Bar'yakhtar, A. N. Bogdanov, and D. A. Yablonskii

Usp. Fiz. Nauk 156, 47-92 (Sept. 1988)
Sov. Phys. Usp. 31 (9), Sept. 1988 (Copyright: American Institute of 
Physics)

The physical principles and basic theses of the theory, enabling a unified 
description of the magnetic properties of all thermodynamically stable 
domain structures in magnets, are presented. The theory is based on the 
following proposition proved by the authors: a necessary condition for the 
formation of all thermodinamically stable domain structures in magnets is 
the existence of a first-order phase transition induced by an external 
magnetic field. The approach developed makes it possible to regard the 
physics of domain structures as a part of thermodinamics, to derived the 
conditions for the existence of domains with different number of phases, 
to study the structure of the region of existence of domains, and to 
formulate for magnets with a domain structure an analogue of Gibbs rule. 
The general assertions od the theory are amply illustrated with 
experimental results. The properties of domain structures are analyzed in 
detail, and an interpretation is given for many experimental results for 
the most studied spin-reorientational transitions.