Affiliation:
1. Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences
Abstract
The spin states of Co atoms in PrBaCo2O5 + δ with regard to the paramagnetic contribution of Pr3+ ions have been determined from magnetic property studies for δ = 0.52 and 0.74. Results obtained without considering the paramagnetic contribution of Pr3+ ions are inconsistent with available experimental data. With a decrease in temperature, the metal–insulator transition in PrBaCo2O5.52 becomes sharper according to a sharp change in spin states (from HS/LS to LS/IS) of Co3+ ions. In this case, Co3+ ions occupying octahedra pass from the high-spin state (HS, S = 2) to the low-spin one (LS, S = 0) and those occupying pyramids pass from the LS-state to the intermediate spin state (IS, S = 1), as follows from the available structural data. In PrBaCo2O5.74, the metal–semiconductor transition occurs smoothly from HS/LS to the HS/IS state upon the smooth transition of the Co3+ ion state from (LS, S = 0) to the (IS, S = 1) state in pyramides without change in the spin state of ions Co3+ (HS, S = 2) and Co4+ (LS, S = 1/2) in octahedrons.
Publisher
The Russian Academy of Sciences
Reference35 articles.
1. A. Maignan, C. Martin, D. Pelloquin et al., J. Sol. St. Chem. 142, 247 (1999).
2. C. Martin, A. Maignan, D. Pelloquin et al., Appl. Phys. Lett. 71, 1421 (1997).
3. A. A. Taskin, A. N. Lavrov, and Yoichi Ando, Phys. Rev. B 71, 134414 (2005).
4. C. Frontera, J. L. Garc'ıa-Munoz, A. Llobet et al., Phys. Rev. B 65, 180405(R) (2002).
5. Y. Moritomo, T. Akimoto, M. Takeo et. al., Phys. Rev. B 61, 13325(R) (2000).