Magnetic and thermal properties of a Haldane chain with one-dimensional ferromagnetic chains in square lattice

Abstract

Since Haldane conjectured that ground state of one-dimensional Heisenberg antiferromagnet has a finite spin gap for integer spins, while gapless excitations for half-odd integer spins, it has inspired lots of theoretical and experimental studies on low-dimensional quantum magnets. Several one-dimensional chain systems of integer spins, so called Haldane chain, have been discovered and studied, such as CsNiCl3, Y2BaNiO5, PbNi2V2O8, SrNi2V2O8, AgVP2S6. It has been known that most of the Haldane chain has antiferromagnetic coupling for the intrachain exchange interaction. Recently, we have found a Haldane chain compound in which antiferromagnetic order is accompanied by antiferromagnetic interchain coupling between one-dimensional ferromagnetic chains below 30.5 Kelvin. In this presentation, we present comprehensive study of its magnetic and thermal properties.