Neutron investigation of Ru-doped Nd_1/2Ca_1/2MnO₃
-Comparison with Cr-doped Nd_1/2Ca_1/2MnO₃-

Abstract

Lattice and magnetic properties are investigated for 3% Ru- and Cr-doped Nd_1/2Ca_1/2MnO₃. The parent Nd_1/2Ca_1/2MnO₃ is a charge-ordered insulator (T_CO = 250 K). With decreasing temperature below ≈ 210 K, these compounds are separated into two perovskite phases, that is, the long-c and short-c phases. The long-c region shows a ferromagnetic transition at T_C ≈ 210 K for the Ru-doped compound and ≈ 130 K for the Cr-doped compound, while the short-c region shows antiferromagnetic transition at T_N ≈ 150 K for Ru and ≈ 110 K for Cr. We discuss the origin of the enhanced T_C for the Ru-doped compound in terms of the effective one-electron bandwidth W of the e_g-band.