Theory of Impurity Effects on the Spin Nematic State

TL;DR

This paper investigates how magnetic bond disorder affects the spin nematic state, revealing impurity-induced anisotropy and interactions that can explain unconventional spin-freezing in triangular magnets like NiGa2S4.

Contribution

It introduces a model with ferromagnetic bond disorder in a bilinear-biquadratic system, showing how impurities induce anisotropic interactions affecting the spin nematic state.

Findings

Impurity magnetic moments couple with bulk excitations, creating anisotropy.

Long-range anisotropic interactions between impurities are established.

These interactions can lead to spin-freezing phenomena in triangular magnets.

Abstract

The effect of magnetic bond disorder in otherwise antiferro nematic ordered system is investigated. We introduced triangular-shaped ferromagnetic bond disorder in the S=1 bilinear-biquadratic model on a triangular lattice. It is shown that the coupling between the impurity magnetic moment and nonmagnetic excitation in the bulk yields single-moment anisotropy and long-range anisotropic interaction between impurity magnetic moments. This interaction can induce unconventional spin-freezing phenomena observed in triangular magnet, NiGa2S4.