General Theory for the Ferroelectric Polarization Induced by Spin-Spiral Order

TL;DR

This paper develops a comprehensive theoretical framework to explain ferroelectric polarization induced by spin-spiral order in triangular-lattice antiferromagnets, integrating and generalizing existing models.

Contribution

It introduces a general theory for spin-spiral-induced ferroelectricity and evaluates its parameters using density functional calculations.

Findings

The theory accurately describes ferroelectricity in triangular-lattice antiferromagnets.

It unifies known models of magnetic-order-driven ferroelectricity as special cases.

The approach provides a predictive tool for related multiferroic materials.

Abstract

The ferroelectric polarization of triangular-lattice antiferromagnets induced by helical spin-spiral order is not explained by any existing model of magnetic-order-driven ferroelectricity. We resolve this problem by developing a general theory for the ferroelectric polarization induced by spin-spiral order and then by evaluating the coefficients needed to specify the general theory on the basis of density functional calculations. Our theory correctly describes the ferroelectricity of triangular-lattice antiferromagnets driven by helical spin-spiral order, and incorporates known models of magnetic-order-driven ferroelectricity as special cases.