Open AccessVacancy induced spin state transition in La0.7Sr0.3-x□xCoO3 (0≤x≤0.2) cobaltites
Author(s) -
解其云,
吴小山
Publication year - 2009
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.58.1229
Subject(s) - superexchange , condensed matter physics , antiferromagnetism , ionic radius , materials science , vacancy defect , ferromagnetism , ground state , ion , physics , atomic physics , quantum mechanics
Effects of vacancy doping in polycrystalline La0.7Sr0.3-xxCoO3 (0≤x≤0.2) cobaltites on their crystal structure, magnetic and transport properties have been systematically investigated. With increasing Sr deficiency, the antiferromagnetic superexchange is promoted at the expense of double exchange between ferromagnetic clusters, with cluster-glass state being prevailing, which is due to the gradual decrease of A site ionic radius as well as more intrinsic disorder. As x is increased beyond 0.1, it is found that the Co—O bond length shrinks remarkably. This tends to enlarge the crystal-field splitting energy and most Co3+ ions are inclined to prefer low spin states. The ground state shows superparamagnetic-like features, thus giving rise to metal-insulator transition.