摘要
A new oxide CaCr0.5Fe0.5O3 was prepared under high pressure and temperature conditions. It crystallizes in a B-site disordered Pbnm perovskite structure. The charge combination is determined to be Cr^5＋/Fe^3＋ with the presence of unusual Cr^5＋ state in octahedral coordination, although Cr^4＋ and Fe^4＋ occur in the related perovskites CaCrO3 and CaFeO3. The randomly distributed Cr^5＋ and Fe^3＋ spins lead to short-range ferromagnetic coupling, whereas an antiferromagnetic phase transition takes place near 50 K due to the Fe^3＋-O-Fe^3＋ interaction. In spite of the B-site Cr^5＋/Fe^3＋ disorder, the compound exhibits electrical insulating behavior. First-principles calculations further demonstrate the formation of CaCr0.5^5＋Fe0.5O3 charge combination, and the electron correlation effect of Fe^3＋ plays an important role for the insulting ground state. CaCr0.5Fe0.5O3 provides the first Cr^5＋ perovskite system with octahedral coordination, opening a new avenue to explore novel transition-metal oxides with exotic charge states.
A new oxide CaCr0.5Fe0.5O3 was prepared under high pressure and temperature conditions. It crystallizes in a B-site disordered Pbnm perovskite structure. The charge combination is determined to be Cr^5＋/Fe^3＋ with the presence of unusual Cr^5＋ state in octahedral coordination, although Cr^4＋ and Fe^4＋ occur in the related perovskites CaCrO3 and CaFeO3. The randomly distributed Cr^5＋ and Fe^3＋ spins lead to short-range ferromagnetic coupling, whereas an antiferromagnetic phase transition takes place near 50 K due to the Fe^3＋-O-Fe^3＋ interaction. In spite of the B-site Cr^5＋/Fe^3＋ disorder, the compound exhibits electrical insulating behavior. First-principles calculations further demonstrate the formation of CaCr0.5^5＋Fe0.5O3 charge combination, and the electron correlation effect of Fe^3＋ plays an important role for the insulting ground state. CaCr0.5Fe0.5O3 provides the first Cr^5＋ perovskite system with octahedral coordination, opening a new avenue to explore novel transition-metal oxides with exotic charge states.
作者
Jian-Hong Dai
Qing Zhao
Qian Sun
Shuo Zhang
Xiao Wang
Xu-Dong Shen
Zhe-Hong Liu
Xi Shen
Ri-Cheng Yu
Ting-Shan Chan
Lun-Xiong Li
Guang-Hui Zhou
Yi-feng Yang
Chang-Qing Jin
You-Wen Long
戴建洪;赵庆;孙倩;张硕;王潇;申旭东;刘哲宏;沈希;禹日成;詹丁山;李论雄;周光辉;杨义峰;靳常青;龙有文(Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physics,University of Chinese Academy of Sciences,Beijing 100049,China;Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201203,China;"National"Synchrotron Radiation Research Center,101 Hsin-Ann Road,Hsinchu 30076,Taiwan,China;Institute for Brain Research and Rehabilitation,South China Normal University,Guangzhou 510631,China;Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications of Hunan,Hunan Normal University,Changsha 410081,China)
基金
Project supported by the National Natural Science Foundation of China(Grant Nos.11574378,51772324,and 61404052)
the National Basic Research Program of China(Grant No.2014CB921500)
the Chinese Academy of Sciences(Grant Nos.YZ201555,QYZDB-SSW-SLH013,GJHZ1773,and XDB07030300)
