Enhanced magnetism in Ru‐doped hybrid improper perovskite Ca <sub>3</sub> Mn <sub>2</sub> O <sub>7</sub> via experimental and first‐principles study
Kejia Yuan, Hanwen Zhang, Qiang Gu, Tianqi Xiao, Zhiyan Li, Winnie K. Wong‐Ng, Wei Zhou, Chao Wang, Shouyu Wang, Weifang Liu
Abstract
Abstract The quasi‐2D Ruddlesden–Popper layered perovskites with single‐phase multiferroicity have attracted much attention in recent magnetoelectric memory applications. We have systematically investigated the optical and magnetic properties of Ru‐doped hybrid improper perovskite Ca 3 Mn 2 O 7 both experimentally and using first‐principles calculations. The Ca 3 Ru x Mn 2− x O 7 ( x = 0, 0.02, 0.06, 0.10) powders were successfully synthesized using the sol–gel method. Ru doping enhanced the ferromagnetism of Ca 3 Mn 2 O 7 . The quasi‐2D antiferromagnetic (AFM) fluctuation effect was observed in Ca 3 Mn 2 O 7 and in certain doped samples. We also found that the optical bandgaps of the doped samples were reduced after doping, agreeing with the results of the first‐principles calculations. Infrared absorption spectra indicated the distortion of the Mn–O bonds was possibly due to the Jahn–Teller effect. To analyze the electronic structures and to understand the detailed atomic contributions of magnetic moments, the Crystal Orbital Hamilton Population (COHP) and Integrated COHP of the (Mn,Ru)O 6 octahedra were also calculated. The Ru‐doped materials with the coexistence of ferromagnetic and AFM orderings are expected to be excellent candidates for magnetoelectric devices.