Kasahara Jun, Katayama Tsukasa, Mo Shishin, Chikamatsu Akira, Hamasaki Yosuke, Yasui Shintaro, Itoh Mitsuru, Hasegawa Tetsuya
Department of Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Department of Applied Physics, National Defense Academy, Yokosuka 239-8686, Japan.
ACS Appl Mater Interfaces. 2021 Jan 27;13(3):4230-4235. doi: 10.1021/acsami.0c20924. Epub 2021 Jan 11.
The antiferroelectric (AFE) phase, in which nonpolar and polar states are switchable by an electric field, is a recent discovery in promising multiferroics of hexagonal rare-earth manganites (ferrites), -Mn(Fe)O. However, this phase has so far only been observed at 60-160 K, which restricts key investigations into the microstructures and magnetoelectric behaviors. Herein, we report the successful expansion of the AFE temperature range (10-300 K) by preparing -DyFeO films through epitaxial stabilization. Room-temperature scanning transmission electron microscopy reveals that the AFE phase originates from a nanomosaic structure comprising AFE 3̅1 and ferroelectric 6 domains with small domain sizes of 1-10 nm. The nanomosaic structure is stabilized by a low / ratio derived from the large ionic radius of Dy. Furthermore, weak ferromagnetism and magnetocapacitance behaviors are observed. Below 10 K, the film exhibits an M-shaped magnetocapacitance versus magnetic field curve, indicating unusual magnetoelectric coupling in the AFE phase.
反铁电（AFE）相是六角形稀土锰酸盐（铁氧体）-Mn(Fe)O这一有前景的多铁性材料中的一项最新发现，在该相中，非极性态和极性态可通过电场切换。然而，到目前为止，此相仅在60 - 160 K的温度范围内被观测到，这限制了对其微观结构和磁电行为的关键研究。在此，我们报告通过外延稳定化制备-DyFeO薄膜成功地扩大了AFE温度范围（10 - 300 K）。室温扫描透射电子显微镜显示，AFE相源自一种纳米镶嵌结构，该结构由AFE 3̅1和铁电6畴组成，畴尺寸小，为1 - 10 nm。这种纳米镶嵌结构通过由Dy的大离子半径导致的低/比得以稳定。此外，还观测到了弱铁磁性和磁电容行为。在10 K以下，该薄膜呈现出磁电容随磁场变化的M形曲线，表明在AFE相中存在异常的磁电耦合。
