Determination of Exchange Parameters for CaV_4O_9

TL;DR

This paper analyzes the magnetic susceptibility of CaV4O9 using high temperature expansion to determine four exchange parameters in a frustrated 2D Heisenberg model, explaining the observed spin gap.

Contribution

It introduces a method to extract exchange parameters from susceptibility data for CaV4O9, revealing strong frustration and explaining the spin gap.

Findings

All exchange parameters are approximately 500 K.

The exchange interactions are strongly frustrated.

The spin gap is attributed to frustration.

Abstract

Magnetic susceptibility measured for CaV$_4$O$_9$ is analyzed by a method with high temperature expansion. The analysis is consistent with the $g$-value which is close to 2 and is observed by an ESR experiment. Four exchange parameters in a two-dimensional Heisenberg model are determined to represent CaV$_4$O$_9$. All the exchange parameters are about 500 K and strongly frustrated. The observed spin gap originates from the frustration.