First-principles theory of magnetically induced ferroelectricity in TbMnO3

TL;DR

This paper uses first-principles calculations to analyze how magnetic spiral order induces ferroelectric polarization in TbMnO3, emphasizing lattice contributions and the effects of spin-orbit coupling.

Contribution

It provides a detailed first-principles analysis of magnetically induced ferroelectricity in TbMnO3, focusing on lattice-mediated polarization and the influence of spin-orbit interaction.

Findings

Lattice-mediated polarization depends on the Coulomb interaction parameter U.

Pure electronic contribution to polarization is small in the studied case.

Spin-orbit interaction plays a significant role on different atomic sites.

Abstract

We study the polarization induced via spin-orbit interaction by a magnetic cycloidal order in orthorhombic TbMnO3 using first-principle methods. The case of magnetic spiral lying in the b-c plane is analyzed, in which the pure electronic contribution to the polarization is shown to be small. We focus our attention on the lattice-mediated contribution, and study it's dependence on the Coulomb interaction parameter U in the LDA+U method and on the wave-vector of the spin spiral. The role of the spin-orbit interaction on different sites is also analyzed.