Field Induced Phase Transitions in Systems with a Crystalline Field Singlet Ground State

概要

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Magnetic field induced phase transitions are studied in a simplified model to repre-sent systems with a crystalline field singlet ground state such as some rare earth compounds by the mean field approximation. In the case where the magnetic field yieldsthe level crossing of the ground and excited states in the absence of the exchange in-teraction, then its presence brings two types of the phase transition. One of them is asecond order transition accompanied with a polarization perpendicular to the field.This is a transition found by Tsuneto and Murao, and Tachiki and Yamada. Anotheris a first order transition, which occurs for the ferromagnetic coupling when theperpendicular susceptibility can not be large enough to yield a spontanous polariza-lion. The system skips over the level crossing from the lower to higher magnetizationstates without change of symmetry. The condition and the nature of these transitionsare investigated.
社団法人日本物理学会の論文
1990-06-15