Spiral ground state in the quasi-two-dimensional spin-1/2 system Cu2GeO4

TL;DR

This study combines computational methods to reveal that Cu2GeO4 has a spiral magnetic ground state due to frustrated interactions, suggesting potential for magnetoelectric effects in this quasi-two-dimensional spin-1/2 system.

Contribution

It introduces a detailed microscopic magnetic model for Cu2GeO4, demonstrating a spiral ground state caused by frustration, which is a novel insight into its magnetic properties.

Findings

Ground state is a spiral with a 84° pitch angle.

Reduced sublattice magnetization is 0.62 μ_B.

Couplings include antiferromagnetic and frustrated interactions.

Abstract

We apply density functional theory band structure calculations, the coupled-cluster method, and exact diagonalization to investigate the microscopic magnetic model of the spin-1/2 compound Cu2GeO4. The model is quasi-two-dimensional, with uniform spin chains along one direction and frustrated spin chains along the other direction. The coupling along the uniform chains is antiferromagnetic, J 130 K. The couplings along the frustrated chains are J1 -60 K and J2 80 K between nearest neighbors and next-nearest neighbors, respectively. The ground state of the quantum model is a spiral, with the reduced sublattice magnetization of 0.62 mu_B and the pitch angle of 84 deg, both renormalized by quantum effects. The proposed spiral ground state of Cu2GeO4 opens a way to magnetoelectric effects in this compound.