Multiferroic behavior in the new double-perovskite Lu$_2$MnCoO$_6$

TL;DR

This study reports the discovery of multiferroic behavior in Lu$_2$MnCoO$_6$, showing coupled magnetic and electric properties below 35 K due to domain boundary effects.

Contribution

It introduces a new double-perovskite multiferroic material and elucidates its magnetic and electric coupling mechanisms involving domain boundaries.

Findings

Electric polarization strongly coupled to magnetization below 35 K

Magnetic order involves $$ and $$ ferromagnetic domains

Magnetoelectric properties controlled by domain boundary movement

Abstract

We present a new member of the multiferroic oxides, Lu$_2$MnCoO$_6$, which we have investigated using X-ray diffraction, neutron diffraction, specific heat, magnetization, electric polarization, and dielectric constant measurements. This material possesses an electric polarization strongly coupled to a net magnetization below 35 K, despite the antiferromagnetic ordering of the $S = 3/2$ Mn$^{4+}$ and Co$^{2+}$ spins in an $\uparrow \uparrow \downarrow \downarrow$ configuration along the c-direction. We discuss the magnetic order in terms of a condensation of domain boundaries between $\uparrow \uparrow$ and $\downarrow \downarrow$ ferromagnetic domains, with each domain boundary producing a net electric polarization due to spatial inversion symmetry breaking. In an applied magnetic field the domain boundaries slide, controlling the size of the net magnetization, electric polarization, and magnetoelectric coupling.