Unusual ferromagnetic superexchange in CdVO3: The role of Cd

TL;DR

This study reveals an unusual ferromagnetic superexchange mechanism in CdVO3, a quasi-one-dimensional spin-1/2 system, where Cd 5s states mediate ferromagnetic interactions, combining theoretical and experimental approaches.

Contribution

It introduces a microscopic magnetic model for CdVO3 highlighting a novel superexchange mechanism involving Cd 5s states, supported by DFT, magnetization measurements, and quantum Monte-Carlo simulations.

Findings

CdVO3 is a rare quasi-1D ferromagnetic system.

The effective intrachain coupling is approximately -90 K.

Interchain couplings partially suppress quantum fluctuations.

Abstract

A microscopic magnetic model of the low-pressure modification of CdVO3 is established, based on density functional theory (DFT) band-structure calculations, magnetization measurements, and quantum Monte-Carlo simulations. This compound is a rare example of a quasi-one-dimensional spin-1/2 system showing exclusively ferromagnetic exchange. The spin lattice of CdVO3 entails zigzag chains with an effective intrachain coupling J ~ -90 K and interchain couplings of Jc ~ -18 K and Ja ~ -3 K. Quantum fluctuations are partially suppressed by the sizable interchain coupling Jc that leads to an intermediate regime between one-dimensional and two-dimensional ferromagnetic systems. Apart from the peculiar spin model, CdVO3 features an unusual mechanism of ferromagnetic superexchange. The couplings largely originate from Cd 5s states mediating hoppings between half-filled and empty 3d states of V+4.