Structural distortion on metal-insulator transition in ordered double perovskite Ca2FeReO6

• Published in: Journal of the Physical Society of Japan Vol. 72; no. 6; pp. 1411 - 1417
• Main Authors: OIKAWA, Kenichi, KAMIYAMA, Takashi, KATO, Hisato, TOKURA, Yoshinori
• Format: Journal Article
• Language: English
• Published: Tokyo Institute of Pure and Applied Physics 01-06-2003; Physical Society of Japan; The Physical Society of Japan
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electron states; Exact sciences and technology; Inorganic compounds; Magnetic properties and materials; Metal-insulator transitions and other electronic transitions; Physics; Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.); Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Water, oxides, hydroxides, peroxides; Temperature dependence; Inorganic compounds; Lattice distortion; Phase transformations; Neutron diffraction; Metal-insulator transition; Transition element compounds; neutron powder diffraction; Coexistence; Spin reorientation; Experimental study; Magnetic transitions; Calcium oxides; Ferrimagnetism; Rhenium oxides; rietveld refinement; Magnetic structure; Local spin density approximation; Ferromagnetism; ordered double perovskite; Iron oxides; Quaternary compounds; Crystal structure; Orbital ordering
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/jpsj.72.1411

The crystal and magnetic structures of an ordered double perovskite, Ca2FeReO6, were studied by high-resolution neutron powder diffraction as a function of the temperature from 7 K to 550 K. All of the diffraction data were precisely refined by the Rietveld method, and we confirmed a structural phase transition at around 140 K where the metal-insulator transition occurs from ferrimagnetic metal (FM) to ferrimagnetic insulator (FI) phases. At this temperature, there exists a change in the distortion direction of [ReO6] octahedra together with a spin reorientation, which strongly supports the occurrence of orbital ordering of the t2g electrons. FM and FI phases coexist in a narrow temperature range at around 140 K, which is typically seen in the first-order phase transition. A phase separation was not detected in our well-characterized sample.