Phase transitions in single-crystalline magnetoelectric LiCoPO4

TL;DR

This study investigates the phase transitions and magnetic properties of LiCoPO4, revealing unique 2D Ising-like behavior near the Neel temperature and a field-induced first-order transition at low temperatures.

Contribution

It provides new insights into the magnetic phase transitions and anisotropy effects in LiCoPO4, including the discovery of a field-induced first-order transition and a theoretical model explaining it.

Findings

Identification of 2D Ising system features near T_N

Discovery of a magnetic field-induced first-order transition at ~9 K

Proposed model explaining the magnetic behavior

Abstract

Specific heat, magnetic torque, and magnetization studies of LiCoPO4 olivine are presented. They show that an unique set of physical properties of LiCoPO4 leads to the appearance of features characteristic of 2D Ising systems near the Neel temperature, T_N =21.6 K, and to the appearance of an uncommon effect of influence of magnetic field on the magnetocrystalline anisotropy. The latter effect manifests itself as a first-order transition, discovered at ~9 K, induced by magnetic field of 8 T. Physical nature of this transition was explained and a model describing experimental dependences satisfactorily was proposed.