Microscopic Origin of Polarization-Controlled Magnetization Switching in FePt/BaTiO$_3$

TL;DR

This paper uses first-principles calculations to reveal how electric-field induced polarization reversal in FePt/BaTiO$_3$ causes a switch in magnetization direction, driven by interfacial orbital reconstruction and strain effects, informing low-power magnetic memory design.

Contribution

It uncovers the microscopic mechanism of polarization-controlled magnetization switching in FePt/BaTiO$_3$, highlighting the role of orbital reconstruction and strain in magnetoelectric coupling.

Findings

Magnetization switches from in-plane to perpendicular upon polarization reversal.

Interfacial magnetoelectric coupling is quantified as $ ext{α}_I = 3.6 imes 10^{-10}$ G·cm$^2$/V.

Strain threshold for switching is approximately 1%.

Abstract

Electric-field driven magnetization switching in FePt/BaTiO$_3$ (001) is demonstrated through first-principles calculations. The magnetic easy axis of FePt layer undergoes a transition from in-plane to perpendicular direction upon ferroelectric polarization reversal, a process sensitively controlled by epitaxial strain with threshold strain strain($\eta$) $\eta\approx\%$. At this phenomena, a large interfacial magnetoelectric coupling ($\alpha_I = 3.6 \times 10^{-10}$ G$\cdot$cm$^2$/V) is responsible, stemming from the orbital reconstruction. In particular, the redistribution of Pt-$d$ orbital occupancy alters spin-orbit coupling, thereby tuning the competition between magnetic anisotropy ($K_i$) and magnetoelastic energy ($b_1$). Our work clarifies the fundamental physics of strain-engineered magnetoelectricity and suggests a concrete pathway for designing ultra-low-power voltage-controlled magnetic memory.