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Title: Crystal structure, magnetic and transport properties, and electronic band structure of A{sub 2}Mn{sub 2}O{sub 7} pyrochlores (A=Y,thinspIn,thinspLu, and Tl)

Abstract

Crystal structures, magnetic and transport properties, and electronic band structures for four compounds with the pyrochlore structure, Tl{sub 2}Mn{sub 2}O{sub 7}, which exhibits colossal magnetoresistive behavior, and insulating A{sub 2}Mn{sub 2}O{sub 7} (A=Y,thinspIn and Lu), are discussed. The cubic unit cell dimensions increase with increasing ionic size of the A{sup 3+} ions. The ferromagnetic behavior is consistent with a superexchange interaction of Mn{sup 4+} spins with an intermediate Mn-O-Mn bond angle of about 130{degree}. In In{sub 2}Mn{sub 2}O{sub 7} and Tl{sub 2}Mn{sub 2}O{sub 7}, strong hybridization of the In(5s)/Tl(6s) orbital with O(2p) and Mn(3d) may enhance the ferromagnetic interaction, leading to high transition temperatures over 120 K. The metallic behavior of Tl{sub 2}Mn{sub 2}O{sub 7} also originates from the hybridization among Tl(6s), O(2p), and Mn(3d). The free-electron-like minority down-spin band crosses the Fermi energy, leading to spin-polarized conduction. At the ferromagnetic Curie temperature, where majority local spins align, spin-polarized conduction electrons are produced: Thus, a ferromagnetic-and-metallic state appears in the Tl{sub 2}Mn{sub 2}O{sub 7} pyrochlore. {copyright} {ital 1999} {ital The American Physical Society}

Authors:
;  [1];  [2]; ; ;  [3]; ;  [4]
  1. Fundamental Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba 305-8501 (Japan)
  2. Department of Physics, Faculty of Science and Technology, Science University of Tokyo, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan)
  3. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
  4. Institute for Solid State Physics, University of Tokyo, 7-22-1, Roppongi, Minato-ku, Tokyo 106-6888 (Japan)
Publication Date:
OSTI Identifier:
289177
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter
Additional Journal Information:
Journal Volume: 59; Journal Issue: 2; Other Information: PBD: Jan 1999
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CURIE POINT; THALLIUM COMPOUNDS; YTTRIUM COMPOUNDS; INDIUM COMPOUNDS; LUTETIUM COMPOUNDS; CRYSTAL STRUCTURE; INDIUM OXIDES; LUTETIUM OXIDES; THALLIUM OXIDES; MANGANESE OXIDES; MAGNETIC PROPERTIES; BAND THEORY; ELECTRONIC STRUCTURE; EXCHANGE INTERACTIONS; HYBRIDIZATION; MAGNETIZATION; SPECIFIC HEAT; PYROCHLORE; SPIN EXCHANGE; POLARIZATION; FERROMAGNETIC MATERIALS

Citation Formats

Shimakawa, Y, Kubo, Y, Hamada, N, Jorgensen, J D, Hu, Z, Short, S, Nohara, M, and Takagi, H. Crystal structure, magnetic and transport properties, and electronic band structure of A{sub 2}Mn{sub 2}O{sub 7} pyrochlores (A=Y,thinspIn,thinspLu, and Tl). United States: N. p., 1999. Web. doi:10.1103/PhysRevB.59.1249.
Shimakawa, Y, Kubo, Y, Hamada, N, Jorgensen, J D, Hu, Z, Short, S, Nohara, M, & Takagi, H. Crystal structure, magnetic and transport properties, and electronic band structure of A{sub 2}Mn{sub 2}O{sub 7} pyrochlores (A=Y,thinspIn,thinspLu, and Tl). United States. doi:10.1103/PhysRevB.59.1249.
Shimakawa, Y, Kubo, Y, Hamada, N, Jorgensen, J D, Hu, Z, Short, S, Nohara, M, and Takagi, H. Fri . "Crystal structure, magnetic and transport properties, and electronic band structure of A{sub 2}Mn{sub 2}O{sub 7} pyrochlores (A=Y,thinspIn,thinspLu, and Tl)". United States. doi:10.1103/PhysRevB.59.1249.
@article{osti_289177,
title = {Crystal structure, magnetic and transport properties, and electronic band structure of A{sub 2}Mn{sub 2}O{sub 7} pyrochlores (A=Y,thinspIn,thinspLu, and Tl)},
author = {Shimakawa, Y and Kubo, Y and Hamada, N and Jorgensen, J D and Hu, Z and Short, S and Nohara, M and Takagi, H},
abstractNote = {Crystal structures, magnetic and transport properties, and electronic band structures for four compounds with the pyrochlore structure, Tl{sub 2}Mn{sub 2}O{sub 7}, which exhibits colossal magnetoresistive behavior, and insulating A{sub 2}Mn{sub 2}O{sub 7} (A=Y,thinspIn and Lu), are discussed. The cubic unit cell dimensions increase with increasing ionic size of the A{sup 3+} ions. The ferromagnetic behavior is consistent with a superexchange interaction of Mn{sup 4+} spins with an intermediate Mn-O-Mn bond angle of about 130{degree}. In In{sub 2}Mn{sub 2}O{sub 7} and Tl{sub 2}Mn{sub 2}O{sub 7}, strong hybridization of the In(5s)/Tl(6s) orbital with O(2p) and Mn(3d) may enhance the ferromagnetic interaction, leading to high transition temperatures over 120 K. The metallic behavior of Tl{sub 2}Mn{sub 2}O{sub 7} also originates from the hybridization among Tl(6s), O(2p), and Mn(3d). The free-electron-like minority down-spin band crosses the Fermi energy, leading to spin-polarized conduction. At the ferromagnetic Curie temperature, where majority local spins align, spin-polarized conduction electrons are produced: Thus, a ferromagnetic-and-metallic state appears in the Tl{sub 2}Mn{sub 2}O{sub 7} pyrochlore. {copyright} {ital 1999} {ital The American Physical Society}},
doi = {10.1103/PhysRevB.59.1249},
journal = {Physical Review, B: Condensed Matter},
number = 2,
volume = 59,
place = {United States},
year = {1999},
month = {1}
}