Quantum Dynamics of Multiferroic Helimagnets: a Schwinger-Boson Approach

TL;DR

This paper investigates the quantum fluctuations in multiferroic helimagnets using a Schwinger boson approach, revealing collinear quantum fluctuations and their effects on physical properties relevant to certain materials.

Contribution

It introduces a Schwinger boson framework to analyze quantum fluctuations in cycloidal helimagnets, highlighting differences from classical behavior and implications for material properties.

Findings

Quantum fluctuations are collinear, unlike classical fluctuations.

A collinear spin density wave state emerges above the helical state.

Insights into neutron scattering and infrared spectra are provided.

Abstract

We study the quantum dynamics/fluctuation of the cycloidal helical magnet in terms of the Schwinger boson approach. In sharp contrast to the classical fluctuation, the quantum fluctuation is collinear in nature which gives rise to the collinear spin density wave state slightly above the helical cycloidal state as the temperature is lowered. Physical properties such as the reduced elliptic ratio of the spiral, the neutron scattering and infrared absorption spectra are discussed from this viewpoint with the possible relevance to the quasi-one dimensional LiCu$_2$O$_2$ and LiCuVO$_4$.