Exchange interactions and magnetic properties of the layered vanadates CaV2O5, MgV2O5, CaV3O7 and CaV4O9

TL;DR

This study uses ab-initio calculations and quantum Monte Carlo simulations to analyze exchange interactions and magnetic properties in layered vanadates, explaining their unique magnetic behaviors and spin gaps.

Contribution

It provides a detailed theoretical analysis of exchange couplings in layered vanadates, explaining their magnetic properties and differences in spin gaps.

Findings

Calculated exchange couplings match experimental susceptibility data.

Explained the large spin gap difference between CaV2O5 and MgV2O5.

Identified the origin of long-range order in CaV3O7 and the plaquette RVB spin gap in CaV4O9.

Abstract

We have performed ab-initio calculations of exchange couplings in the layered vanadates CaV2O5, MgV2O5, CaV3O7 and CaV4O9. The uniform susceptibility of the Heisenberg model with these exchange couplings is then calculated by quantum Monte Carlo method; it agrees well with the experimental measurements. Based on our results we naturally explain the unusual magnetic properties of these materials, especially the huge difference in spin gap between CaV2O5 and MgV2O5, the unusual long range order in CaV3O7 and the "plaquette resonating valence bond (RVB)" spin gap in CaV4O9.