Room-temperature surface multiferroicity in Y${}_2$NiMnO${}_6$ nanorods

Abstract

We report observation of surface-defect-induced room temperature multiferroicity - surface ferromagnetism ($M_S$ at 50 kOe $\sim$0.005 emu/g), ferroelectricity ($P_R$ $\sim$2 nC/cm${}^2$), and significantly large magnetoelectric coupling (decrease in $P_R$ by $\sim$80\% under $\sim$15 kOe field) - in nanorods (diameter $\sim$100 nm) of double perovskite Y${}_2$NiMnO${}_6$ compound. In bulk form, this system exhibits multiferroicity only below its magnetic transition temperature $T_N$ $\approx$ 70 K. On the other hand, the oxygen vacancies, formed at the surface region (thickness $\sim$10 nm) of the nanorods, yield long-range magnetic order as well as ferroelectricity via Dzyloshinskii-Moriya exchange coupling interactions with strong Rashba spin-orbit coupling. Sharp drop in $P_R$ under magnetic field indicates strong cross-coupling between magnetism and ferroelectricity as well. Observation of room temperature magnetoelectric coupling in nanoscale for a compound which, in bulk form, exhibits multiferroicity only below 70 K underscores an alternative pathway for inducing magnetoelectric multiferroicity via surface defects and, thus, in line with magnetoelectric property observed, for example, in domain walls or boundaries or interfaces of heteroepitaxially grown thin films which do not exhibit such features in their bulk.

10 pages, 7 figures, published in Phys. Rev. B

References in corpus (6)

• Ferromagnetism as a universal feature of nanoparticles of the otherwise nonmagnetic oxides
• Emergent Phenomena Induced by Spin-Orbit Coupling at Surfaces and Interfaces
• Interaction effects in assembly of magnetic nanoparticles
• Determination of intrinsic ferroelectric polarization in lossy improper ferroelectric systems
• Direct Observation of Unusual Interfacial Dzyaloshinskii-Moriya Interaction in Graphene/NiFe/Ta Heterostructure
• Effect of surface pinning on magnetic nanostuctures