Magnetoelectric Coupling and Decoupling in Multiferroic Hexagonal YbFeO3 Thin Films

Abstract

Electric-field driven magnetization reversal has been an appealing example of magnetoelectric effect (ME) that is promising for applications. In this work, we explore this effect in thin-film hexagonal YbFeO₃, a multiferroic material exhibiting both spontaneous polarization and magnetization originating from structural distortions, suggesting the possibility of structural-mediated ME. Using x-ray magnetic circular dichroism (XMCD) measurements, the response of magnetization to the in-situ ferroelectric switching process was studied. We found that the full reversal of polarization has minimal effect on magnetization, indicating that ferromagnetic domains and ferroelectric domains are decoupled. Analysis using the Landau theory reveals that although the polarization reversal changes the structural distortion followed by the spin reorientation, the magnetization reversal requires overcoming additional energy barriers. On the other hand, correlation between the reduction in the magnitude of magnetization and zero polarization was observed experimentally, demonstrating less magnetization of the ferroelectric domain-walls compared with that of the domains; this can be understood as the magnetic domain walls clamped on the ferroelectric domain walls that causes the reduction of magnetization when ferroelectric domain wall population increases. These results provide important experimental evidence and theoretical insights into the rich possibilities of magnetoelectric effects and coupling mechanisms, paving way to controlling the local magnetic states using electric field in hexagonal ferrites.