Physical Properties of the Quasi-Two-Dimensional Square Lattice Antiferromagnet Ba2FeSi2O7

Published

December 28, 2021

Author(s)

Tae-Hwan Jang, Seung-Hwan Do, Minseong Lee, Hui Wu, Craig Brown, Andrew D. Christianson, Sang-Wook Cheong, Jae-Hoon Park

Abstract

We report magnetization (χ, M), magnetic specific heat (CM), and neutron powder diffraction results on a quasi-two-dimensional (2D) S = 2 square lattice antiferromagnet Ba₂FeSi₂O₇ consisting of FeO₄ tetrahedrons with highly compressive tetragonal distortion (27%). Despite of the quasi-2D lattice structure, both χ and CM present three dimensional magnetic long-range ordering below the Néel temperature TN = 5.2 K. Neutron diffraction data shows a collinear Q_m = (1,0,1/2) antiferromagnetic (AFM) structure below TN but the ordered moment aligned in the ab plane is suppressed by 26% from the ionic spin S = 2 value (4μB) . Both the AFM structure and the suppressed moments are well explained by using Monte Carlo simulations with a large single-ion in-plane anisotropy D = 1.4 meV and a rather small Heisenberg exchange J_intra = 0.15 meV in the plane. The characteristic 2D spin fluctuations are recognized in the magnetic entropy release and diffuse scattering above T_N. This new quasi-2D magnetic system also displays unusual non-monotonic dependence of T_N as a function of magnetic field H.

Citation

Physical Review B

Volume

104

Issue

21

Pub Type

Journals

Keywords

Neutron diffraction, Magnetization measurements, Antiferromagnets, Magnetic insulators, Magnetic insulators, Monte Carlo methods

Citation

Jang, T. , Do, S. , Lee, M. , Wu, H. , Brown, C. , Christianson, A. , Cheong, S. and Park, J. (2021), Physical Properties of the Quasi-Two-Dimensional Square Lattice Antiferromagnet Ba₂FeSi₂O₇, Physical Review B (Accessed October 21, 2025)