Tuning the Neel Temperature of Hexagonal Ferrites by Structural Distortion
Authors: Sinha, K; Wang, HH; Wang, X; Zhou, LY; Yin, YW; Wang, WB; Cheng, XM; Keavney, DJ; Cao, HB; Liu, YH; Wu, XF; Xu, XS
Source: PHYSICAL REVIEW LETTERS, 121 (23):10.1103/PhysRevLett.121.237203 DEC 7 2018
Publication Type: Article
Abstract: To tune the magnetic properties of hexagonal ferrites, a family of magnetoelectric multiferroic materials, by atomic-scale structural engineering, we studied the effect of structural distortion on the magnetic ordering temperature (T-N) in these materials. Using the symmetry analysis, we show that unlike most antiferromagnetic rare-earth transition-metal perovskites, a larger structural distortion leads to a higher T-N in hexagonal ferrites and manganites, because the K-3 structural distortion induces the three-dimensional magnetic ordering, which is forbidden in the undistorted structure by symmetry. We also revealed a near-linear relation between T-N and the tolerance factor and a power-law relation between T-N and the K-3 distortion amplitude. Following the analysis, a record-high T-N (185 K) among hexagonal ferrites was predicted in hexagonal ScFeO3 and experimentally verified in epitaxially stabilized films. These results add to the paradigm of spin-lattice coupling in antiferromagnetic oxides and suggests further tunability of hexagonal ferrites if more lattice distortion can be achieved.