Physical properties of a quasi-two-dimensional square lattice antiferromagnet Ba$_2$FeSi$_2$O$_7$

Tae-Hwan Jang; Seung-Hwan Do; Minseong Lee; Vivien S. Zapf; Hui Wu; Craig M. Brown; Andrew D. Christianson; Sang-Wook Cheong; Jae-Hoon Park

doi:10.1103/PhysRevB.104.214434

paper

Physical properties of a quasi-two-dimensional square lattice antiferromagnet Ba $_{2}$ FeSi $_{2}$ O $_{7}$

arXiv:2108.00999 · doi:10.1103/PhysRevB.104.214434

Abstract

We report the magnetization ( $χ$ , $M$ ), specific heat ( $C_{P}$ ), and neutron powder diffraction results on a quasi-two-dimensional $S$ = 2 square lattice antiferromagnet Ba $_{2}$ FeSi $_{2}$ O $_{7}$ consisting of FeO $_{4}$ tetragons with a large compressive distortion (27%). Despite of the quasi-two-dimensional lattice structure, both $χ$ and $C_{P}$ present three dimensional magnetic long-range order below the Néel temperature $T_{N}$ = 5.2 K. Neutron diffraction data shows a collinear $Q_{m}$ = (1,0,0.5) antiferromagnetic (AFM) structure with the in-plane ordered magnetic moment suppressed by 26% below $T_{N}$ . Both the AFM structure and the suppressed moments are well explained by the Monte Carlo simulation with a large single-ion ab-plane anisotropy $D$ = 1.4 meV and a rather small in-plane Heisenberg exchange $J_{intra}$ = 0.15 meV. The characteristic two dimensional spin fluctuations can be 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 the $T_{N}$ as a function of magnetic field $H$ .

23 pages

Physical properties of a quasi-two-dimensional square lattice antiferromagnet Ba $_{2}$ FeSi $_{2}$ O $_{7}$

Abstract

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Physical properties of a quasi-two-dimensional square lattice antiferromagnet Ba2​FeSi2​O7​

Abstract

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Physical properties of a quasi-two-dimensional square lattice antiferromagnet Ba $_{2}$ FeSi $_{2}$ O $_{7}$