Magnetic Properties of a Quasi-two-dimensional Heisenberg Antiferromagnet α -RbCrF4

Abstract

We synthesized a quasi-two-dimensional Heisenberg antiferromagnet on a square lattice formed in α -RbCrF4 by improving the pretreatment method before primary sintering. From X-ray diffraction measurements, the crystal structure was found to consist of a TlAlF4-type structure, which shows a good two-dimensionality. But the splitting of the fundamental peak indicating a superstructure in the ab-plane appeared. Temperature dependence of magnetic susceptibility shows a broad peak, which indicates typical low-dimensional antiferromagnets, at Tmax ≈ 47K . Furthermore, a sharp peak which indicates an antiferromagnetic phase transition also appeared at TN = 29.3(2) K. Following several previous theoretical investigations, we estimated intra-layer (Jintra) and inter-layer (Jinter) exchange interactions to be Jintra/ KB = -6.6(1) K  and Jinter / Jintra ≈ 0.05 , respectively. As a result, we found that α -RbCrF4 is a quasi-two-dimensional Heisenberg antiferromagnet.