Investigation of spin transition in GdCoO3 by measuring the electric field gradient at Co sites

被引:5
作者
Cavalcante, F. H. M.
Carbonari, A. W.
Malavasi, R. F. L.
Cabrera-Pasca, G. A.
Saxena, R. N.
Mestnik, J.
机构
[1] Instituto de Pesquisas Energeticas e Nucleares, IPEN-CNEN/SP
基金
巴西圣保罗研究基金会;
关键词
rare-earth oxides; cobaltites; electric field gradient; perturbed angular correlation;
D O I
10.1016/j.jmmm.2008.02.033
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
In the present work, the time differential perturbed angular correlation (PAC) technique was used to study the temperature dependence of electric field gradient (efg) in GdCoO3 perovskite using Cd-111 and Ta-181 nuclear probes. The radioactive parent nuclei In-111 and Hf-181 were introduced in the oxide lattice through chemical process during sample preparation and were found to occupy only the Co sites in GdCoO3. The efg's at Cd-111 and Ta-181 show temperature dependence with two different fractions each that change with temperature. In the case of Cd-111 the quadrupole frequency slowly decreases, with corresponding increase of the temperature and shows a peak like structure at around 200K and a discontinuity at 700 K. These changes have been interpreted as thermally activated spin-state transitions from low-spin ground state configuration to the intermediate-spin state and from intermediate-spin to high-spin state of Co3+ ion similar to LaCoO3 compound. Indication of a Jahn-Teller distortion, which stabilizes the intermediate-spin state with orbital ordering, is also pointed out. (C) 2008 Elsevier B.V. All rights reserved.
引用
收藏
页码:E32 / E35
页数:4
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