SPIN-STATE AND HYPERFINE INTERACTION IN LACOO3 - NMR AND MAGNETIC-SUSCEPTIBILITY STUDIES
SPIN-STATE AND HYPERFINE INTERACTION IN LACOO3 - NMR AND MAGNETIC-SUSCEPTIBILITY STUDIES
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DOI：
10.1143/jpsj.64.3967
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发表时间：
1995-10-01
影响因子：
1.7
通讯作者：
MOTOYA, K
中科院分区：
文献类型：
--
作者：
ITOH, M;SUGAHARA, M;MOTOYA, K
用Co-59和La-139核磁共振方法研究了与LaCoO_3中三价钴离子自旋态密切相关的微观磁性质。与温度无关的Co-59和La-139在30K以下的Knight位移清楚地揭示了低温下非磁性基态的存在。我们计算了具有低自旋(1)A(1)基态的单离子模型的磁化率chi和Co-59 Knight Shift K-59随温度的变化，高自旋T-5(2)态位于该基态之上。然后，同时考虑了三角晶场和自旋轨道相互作用。从这个分析中，我们推断出高自旋态之间存在反铁磁交换相互作用。讨论了Co-59超精细耦合常数随温度变化的特征。
Co-59 and La-139 NMR measurements have been performed to study the microscopic magnetic properties closely related with the spin state of a trivalent cobalt ion in LaCoO3. The temperature-independent Co-59 and La-139 Knight shifts below similar to 30 K clearly revealed the presence of a nonmagnetic ground state at low temperatures. We calculated the temperature dependence of the magnetic susceptibility chi and the Co-59 Knight shift K-59 in a single ion model with the low-spin (1)A(1) ground state above which the high-spin T-5(2) State is located. Then, both the trigonal crystal-field and spin-orbit interactions are taken into account. From this analysis, we infer the presence of an antiferromagnetic exchange interaction between the high-spin states. The characteristic temperature dependence of the Co-59 hyperfine coupling constant is also discussed.