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Mn2MnReO6: Synthesis and Magnetic Structure Determination of a New Transition-Metal-Only Double Perovskite Canted Antiferromagnet

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posted on 13.04.2016, 00:00 authored by Man-Rong Li, Jason P. Hodges, Maria Retuerto, Zheng Deng, Peter W. Stephens, Mark C. Croft, Xiaoyu Deng, Gabriel Kotliar, Javier Sánchez-Benítez, David Walker, Martha Greenblatt
Transition-metal-only double perovskite oxides (A2BB′O6) are of great interest due to their strong and unusual magnetic interactions; only one compound, Mn2FeReO6, was reported in this category to date. Herein, we report the second transition-metal-only double perovskite, Mn2MnReO6, prepared at high pressure and temperature. Mn2MnReO6 crystallizes in a monoclinic P21/n structure, as established by synchrotron X-ray and powder neutron diffraction (PND) methods, with eight-coordinated A sites and rock-salt arrangement of the B and B′-site MnO6 and ReO6. Both the structural analysis and the X-ray absorption near edge spectroscopy results indicate mixed valence states of the B/B′-site in Mn2+2Mn2+/3+Re5+/6+O6. The magnetic and PND studies evidence an antiferromagnetic (AFM) transition at ∼110 K and a transition from a simple AFM to canted AFM with net ferromagnetic component at ∼50 K. The observed Efros–Shklovskii variable-range-hopping semiconducting behavior is attributed to the three (A-site Mn2+, B-site Mn2+/3+, and B′-site Re5+/6+) interpenetrating canted AFM lattices. Theoretical calculations demonstrate that the almost fully polarized Mn states in Mn2MnReO6 are driven away from the Fermi level by static on-site interactions and open a small gap, which is responsible for the insulating state in such a d-electron-rich system. These results provide insight of the electronic origin of the physical properties of Mn2MnReO6 with local electronic structure similar to that of Mn2FeReO6.