Magnetic Structure and Interactions in the Quasi-1D Antiferromagnet CaV$_2$O$_4$

TL;DR

This paper investigates the magnetic structure of CaV$_2$O$_4$, revealing a transition from a Haldane chain at high temperatures to a spin-1 ladder at low temperatures due to orbital ordering.

Contribution

It provides detailed experimental insights into the magnetic interactions and orbital configurations in CaV$_2$O$_4$, highlighting a temperature-induced change in magnetic behavior.

Findings

CaV$_2$O$_4$ behaves as a Haldane chain at high temperatures.

Orbital ordering at low temperatures lifts frustration.

Transition to a spin-1 ladder at low temperatures.

Abstract

CaV$_2$O$_4$ is a spin-1 antiferromagnet, where the magnetic vanadium ions are arranged on quasi-one-dimensional (1D) zig-zag chains with potentially frustrated antiferromagnetic exchange interactions. High temperature susceptibility and single-crystal neutron diffraction measurements are used to deduce the non-collinear magnetic structure, dominant exchange interactions and orbital configurations. The results suggest that at high temperatures CaV$_2$O$_4$ behaves as a Haldane chain, but at low temperatures, orbital ordering lifts the frustration and it becomes a spin-1 ladder.