Neutron Scattering Study of CoO(6) Distortion and Its Relation to the Spin-State Transition in Pr(0.5)Ca(0.5)CoO(3)

作者：Tong Peng^*; Wu Yongsu; Kim Bongju; Kwon Daeyoung; Park J M Sungil; Kim Bog G

来源：Journal of the Physical Society of Japan, 2009, 78(3): 034702.

DOI：10.1143/JPSJ.78.034702

• Pr(0.5)Ca(0.5)CoO(3)
• spin-state transition
• oxygen deficiency
• neutron powder diffraction
• electron-lattice coupling

This study compares the electrical resistivity, magnetization, and high-resolution neutron powder diffraction data obtained for Pr(0.5)Ca(0.5)CoO(3) and Pr(0.5)Ca(0.5)CoO(3-delta) (delta similar to 0.045). Although both samples exhibit similar structural parameters, the distortion of the CoO(6) octahedra is weaker in Pr(0.5)Ca(0.5)CoO(3-delta) than in Pr(0.5)Ca(0.5)CoO(3) at low temperatures. This reduced distortion decreases the electron-lattice coupling, which increases the itinerant nature of the e. electrons in the oxygen-deficient sample. In addition, the oxygen deficiency can add Co(3 ) ions into Pr(0.5)Ca(0.5)CoO(3-delta), yielding an increased population of e(g) electrons. As a result, the sharp spin-state transition observed in Pr(0.5)Ca(0.5)CoO(3) is suppressed in Pr(0.5)Ca(0.5)CoO(3-delta), which exhibits a lower magnitude of resistivity and stronger magnetism at low temperatures.

• 出版日期2009-3