Magnetic properties and coupled spin-phonon behavior in quasi-one-dimensional screw-chain compound BaMn2V2O8

Abstract

Spin-chain compounds are known to exhibit fascinating magnetic properties, which mostly display magnetic ordering at very low temperatures or remain dynamic even at 0 K. In contrast, the present quasi-one-dimensional spin-chain system $\mathrm{Ba}{\mathrm{Mn}}_{2}{\mathrm{V}}_{2}{\mathrm{O}}_{8}$ exhibits a collinear antiferromagnetic (AFM) long-range ordering at a relatively higher temperature ${T}_{\mathrm{N}}\ensuremath{\sim}37\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, wherein the nearest-neighbor spins have AFM coupling along the spin chain, i.e., along the $c$ axis. The present study also reveals a short-range magnetic ordering prevailing at considerably elevated temperatures above its ${T}_{\mathrm{N}}$. Temperature-dependent Raman spectroscopy demonstrates an occurrence of spin-phonon coupling below ${T}_{\mathrm{N}}$ at least for two phonon modes, whereas the study also shows an unusual thermal evolution of the Raman modes above ${T}_{\mathrm{N}}$, which is apparently associated to the short-range magnetic ordering. Furthermore, extensive ab initio density functional theory calculations accompanied with classical Heisenberg model based theoretical calculations of various exchange interaction parameters $({J}_{0}--{J}_{5})$ suggest an AFM ground state, which matches well with the experimentally obtained spin structure.