Spiral plane flops in frustrated helimagnets in external magnetic field

TL;DR

This paper theoretically investigates how small anisotropic interactions influence the spiral plane orientation in frustrated helimagnets under magnetic fields, deriving critical fields for plane flops and proposing experimental measurement methods.

Contribution

It introduces a theoretical framework for understanding spiral plane flops in frustrated helimagnets and links critical field measurements to anisotropy quantification.

Findings

Derived expressions for critical flop fields $H_{flop}$

Showed measurement of $H_{flop}$ as a method to quantify anisotropy

Analyzed recent experiments in multiferroic spiral magnets

Abstract

We discuss theoretically frustrated Heisenberg spiral magnets in magnetic field $\bf H$. We demonstrate that small anisotropic spin interactions (single-ion biaxial anisotropy or dipolar forces) select the plane in which spins rotate (spiral plane) and can lead to the spiral plane flop upon in-plane field increasing. Expressions for the critical fields $H_{flop}$ are derived. It is shown that measuring of $H_{flop}$ is an efficient and simple method of quantifying the anisotropy in the system (as the measurement of spin-flop fields in collinear magnets with axial anisotropy). Corresponding recent experiments are considered in spiral magnets some of which are multiferroics of spin origin.