Pressure-induced charge orders and their postulated coupling to magnetism in hexagonal multiferroic LuFe₂O₄

Authors

Fengliang Liu, Fudan University, Center for High Pressure Science and Technology Advanced Research, Nanchang University
Yiqing Hao, Fudan University,
Jinyang Ni, Fudan University,
Yongsheng Zhao, Center for High Pressure Science and Technology Advanced Research
Dongzhou Zhang, University of Hawaii Manoa
Gilberto Fabbris, Argonne National Laboratory
Daniel Haskel, Argonne National Laboratory
Shaobo Cheng, Brookhaven National Laboratory
Xiaoshan XuFollow
Lifeng Yin, Fudan University, Collaborative Innovation Center of Advanced Microstructures, Shanghai Qi Zhi Institute, Shanghai Research Center for Quantum Sciences
Hongjun Xiang, Fudan University, Collaborative Innovation Center of Advanced Microstructures
Jun Zhao, Fudan University, Collaborative Innovation Center of Advanced Microstructures, Shanghai Qi Zhi Institute
Xujie Lü
Wenbin Wang, Fudan University, Collaborative Innovation Center of Advanced Microstructures, Shanghai Qi Zhi Institute, Shanghai Research Center for Quantum Sciences
Jian Shen, Fudan University, Collaborative Innovation Center of Advanced Microstructures, Shanghai Qi Zhi Institute, Shanghai Research Center for Quantum Sciences
Wenge Yang, Center for High Pressure Science and Technology Advanced Research

Date of this Version

1-7-2023

Citation

npj Quantum Materials (2023) 8:1 ; https://doi.org/10.1038/s41535-022-00522-x

Comments

Open access.

Abstract

Hexagonal LuFe₂O₄ is a promising charge order (CO) driven multiferroic material with high charge and spin-ordering temperatures. The coexisting charge and spin orders on Fe³⁺/Fe²⁺ sites result in magnetoelectric behaviors, but the coupling mechanism between the charge and spin orders remains elusive. Here, by tuning external pressure, we reveal three charge-ordered phases with suggested correlation to magnetic orders in LuFe₂O₄: (i) a centrosymmetric incommensurate three-dimensional CO with ferrimagnetism, (ii) a non-centrosymmetric incommensurate quasi-two-dimensional CO with ferrimagnetism, and (iii) a centrosymmetric commensurate CO with antiferromagnetism. Experimental in situ single-crystal X-ray diffraction and X-ray magnetic circular dichroism measurements combined with density functional theory calculations suggest that the charge density redistribution caused by pressure-induced compression in the frustrated double-layer [Fe₂O₄] cluster is responsible for the correlated spin-charge phase transitions. The pressure-enhanced effective Coulomb interactions among Fe-Fe bonds drive the frustrated (1/3, 1/3) CO to a less frustrated (1/4, 1/4) CO, which induces the ferrimagnetic to antiferromagnetic transition. Our results not only elucidate the coupling mechanism among charge, spin, and lattice degrees of freedom in LuFe₂O₄, but also provide a new way to tune the spin-charge orders in a highly controlled manner.