X-ray imaging and multiferroic coupling of cycloidal magnetic domains in ferroelectric monodomain BiFeO3

TL;DR

This study uses hard X-ray magnetic scattering to image magnetic domains in ferroelectric BiFeO3, revealing cycloidal modulations, a unique magnetization rotation, and vortex structures, advancing understanding of multiferroic coupling.

Contribution

It provides the first direct imaging of magnetic domains and their cycloidal modulations in BiFeO3 using X-ray scattering, confirming theoretical predictions.

Findings

Magnetic domains up to hundreds of microns observed

Cycloidal modulations of magnetization identified

A 120-degree vortex structure at domain boundaries

Abstract

Magnetic domains at the surface of a ferroelectric monodomain BiFeO3 single crystal have been imaged by hard X-ray magnetic scattering. Magnetic domains up to several hundred microns in size have been observed, corresponding to cycloidal modulations of the magnetization along the wave-vector k=2\pi(\delta,\delta,0) and symmetry equivalent directions. The rotation direction of the magnetization in all magnetic domains, determined by diffraction of circularly polarized light, was found to be unique and in agreement with predictions of a combined approach based on a spin-model complemented by relativistic density-functional simulations. Imaging of the surface shows that the largest adjacent domains display a 120 degree vortex structure.