Magnetic ground state and the spin-state transitions in YBaCo2O5.5
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The crystal and magnetic structure of the perovskite-like, oxygen deficient cobalt oxide YBaCo2O5.5 has been studied by means of neutron and X-ray diffraction in the 10–300 K temperature range. The magnetic ground state is characterized by a coexistence of two distinct antiferromagnetic phases. In the first one, the ionic moments of high-spin Co3+ ions in the pyramidal sites are ordered in a spiral arrangement, while octahedral sites are non-magnetic due to presence of low-spin Co3+ ions. The arrangement in the second phase is collinear of the G-type, with non-zero moments both in pyramidal (high-spin Co3+ ions) and octahedral sites (presumably a mixture of the low- and high-spin states). With increasing temperature, at 260–300 K, the system develops a gradual structural transformation, which is associated with appearance of spontaneous magnetic moment. This process is related to a thermally induced reversion of low- and high-spin states at the octahedral sites to the intermediate-spin Co3+ states, resulting in an insulator-metal transition at TC ≈ TIM ≈ 295 K.
PACS75.25.+z Spin arrangements in magnetically ordered materials 61.05.fm Neutron diffraction
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- 28.V.P. Glazkov, I.N. Goncharenko, Fizika I Tekhnika Vysokih Davlenij 1, 56 (1991) (in Russian)Google Scholar
- 30.J. Rodríguez-Carvajal, Physica B 55, 192 (1993)Google Scholar
- 33.R.B. Von Dreele, A.C. Larson, Los Alamos National Laboratory Report No. LAUR 86, 1986 p. 748Google Scholar