Magnetic ordering and spin dynamics in $S=5/2$ staggered triangular lattice antiferromagnet Ba$_2$MnTeO$_6$

TL;DR

This study investigates the magnetic properties and spin dynamics of the $S=5/2$ staggered triangular lattice antiferromagnet Ba$_2$MnTeO$_6$, revealing its magnetic order, exchange interactions, and the role of competing interactions in stabilizing its magnetic phase.

Contribution

The paper combines experimental techniques and first-principles calculations to elucidate the magnetic interactions and phase stability in Ba$_2$MnTeO$_6$, providing new insights into its complex magnetic behavior.

Findings

Neutron diffraction shows antiferromagnetic order with T_N ≈ 20 K.

Exchange interactions J_1 and J_2 are approximately 0.27 meV, J_3 is -0.05 meV.

Magnetic phase diagram indicates competition among J_1, J_2, and J_3 stabilizes stripe order.

Abstract

We report studies of the magnetic properties of a staggered stacked triangular lattice Ba$_2$MnTeO$_6$ using magnetic susceptibility, specific heat, neutron powder diffraction and inelastic neutron scattering measurements, as well as first principles density functional theory calculations. Neutron diffraction measurements reveal an antiferromagnetic order with a propagated vector $\textbf{\emph{k}}=(0.5, 0.5, 0)$ and N{\'{e}}el transition temperature of $T_\text{N}\approx20$ K. The dominant interaction derived from the Curie-Weiss fitting to the inverse DC susceptibility is antiferromagnetic. Through modelling the INS spectrum with the linear spin wave theory, the magnetic exchange interactions for the nearest intralayer, nearest interlayer, and next nearest interlayer are determined to be $J_1=0.27(3),J_2=0.27(3),$ and $J_3=-0.05(1)$ meV, respectively, and a small value of easy-axis anisotropy of $D_{zz}=-0.01$ meV is introduced. We derive a magnetic phase diagram that reveals that it is the competition between $J_1, J_2$, and $J_3$ that stabilizes the collinear stripe-type antiferromagnetic order.