Structural Phase Transitions with Ferroelectricity in a Hexagonal Antiferromagnetic Compound: TlFeCl₃

Abstract

In order to clarify structural and magnetic phase transitions of a hexagonal triangular antiferromagnet TlFeCl 3 , dielectric and magnetic susceptibilities, D – E hysteresis loops and optical birefringence were measured. Successive structural phase transitions at 179 K( T 2 ), 83 K( T 3 ) and 79 K( T 4 ) were identified. At a range of temperatures T 4 < T < T 3 (phase IV), opened D – E loops were clearly observed. The dielectric behavior of the successive structural phase transitions of TlFeCl 3 were confirmed to be quite similar to those of KNiCl 3 and RbMnBr 3 which are Group I of KNiCl 3 -family crystals.