Manipulation of spin orientation via ferroelectric switching in Fe-doped Bi2WO6 from first principles

TL;DR

This study uses first-principles calculations to explore how ferroelectric switching in Fe-doped Bi2WO6 can manipulate spin orientation, revealing a pathway for electric field-controlled spin control in magnetic ferroelectric materials.

Contribution

It identifies the ferroelectric switching pathways in Bi2WO6 and demonstrates how electric field-induced polarization changes can reorient magnetic spins in Fe-doped variants.

Findings

A two-step ferroelectric switching pathway with low energy barrier.

A 90-degree polarization switch causes a 112-degree spin reorientation.

Magnetoelastic coupling enables electric field control of spins.

Abstract

Atomic-scale control of spins by electric fields is highly desirable for future technological applications. Magnetically-doped Aurivillius-phase oxides present one route to achieve this, with magnetic ions substituted into the ferroelectric structure at dilute concentrations, resulting in spin-charge coupling. However, there has been minimal exploration of the ferroelectric switching pathways in this materials class, limiting predictions of the influence of an electric field on the magnetic spins in the structure. Here, we determine the ferroelectric switching pathways of the end member of the Aurivilius phase family, Bi2WO6, using a combination of group theoretic analysis and density functional theory calculations. We find that in the ground state P21ab phase, a two-step switching pathway via C2 and Cm intermediate phases provides the lowest energy barrier. Considering iron substitutions on the W-site in Bi2WO6, we determine the spin easy axis. By tracking the change in spin directionality during ferroelectric switching, we find that a 90 degree switch in the polarization direction leads to a 112 degree reorientation of the spin easy axis. The low symmetry crystal-field environment of Bi2WO6 and magnetoelastic coupling on the magnetic dopant provide a route to spin control via and applied electric field.