Magnetic crossover and complex excitation spectrum of the ferromagnetic/antiferromagnetic spin-1/2 chain system alpha-TeVO4

TL;DR

This study investigates the magnetic properties and excitation spectrum of alpha-TeVO4, revealing a crossover at 85 K and a magnetic phase transition at 16 K, highlighting complex spin interactions and lattice coupling.

Contribution

It provides new experimental insights into the magnetic crossover and excitation spectrum of alpha-TeVO4, a system with ferromagnetic/antiferromagnetic spin chains, and interprets the microscopic mechanisms involved.

Findings

Crossover at T* = 85 K with different susceptibility slopes

Magnetic phase transition at Tc = 16 K to long-range order

Strong coupling between lattice and magnetic degrees of freedom

Abstract

We report magnetic susceptibility, specific heat, and Raman scattering investigations of alpha-TeVO4 containing V-O edge-sharing chains. These chains promote a system of ferromagnetic/antiferromagnetic spin-1/2 Heisenberg alternating exchange chains with pronounced spin frustration. The magnetic susceptibility and Raman scattering evidence a crossover at T* = 85 K with different slopes of the reciprocal susceptibility and a magnetic phase transition into a long-range-ordered state at Tc = 16 K. From Raman scattering data a strong mutual coupling between lattice and magnetic degrees of freedom is deduced. A comparison to model calculations and prior Raman scattering on other chain systems yield a plausible interpretation of the microscopic mechanism for the crossover behavior.