Thermopower in Pr_<1-x>Ca_xMnO_3 : Condensed Matter: Electronic Properties, etc.

概要

論文の詳細を見る
We report measurements of thermopower in Pr_<1-x>Ca_xMnO_3 (0.33 ≤ x ≤ 0.48). A clear anomaly has been observed at the charge ordering temperature T_<co> for x = 0.33, 0.34, 0.47 and 0.48. Negative thermopower below T_<co> shows that the carriers are of electron-type in the charge-ordering state of x = 0.47 and 0.48. This indicates that the hopping of e_g electrons at the Mn^<4+> sublattice, i.e., extra Mn^<3+> ions, dominates the transport properties in the charge-ordering phase. Thermopower below T_<co> changes from negative to positive around x 〜 0.35 as the e_g~electron number (1 - x) increases, which implies a spatial ordering of extra Mn^<3+> ions. The ordering of extra Mn^<3+> ions possibly stabilizes the 1:1 commensurate charge ordering with the wave vector of (100) with x far from the commensurate composition, x = 0.50. Thermopower is found to be significantly dependent on magnetic field. The result should be closely related to the stability of the charge ordering in a magnetic field.
社団法人日本物理学会の論文
2000-05-15