Structural, magnetic, and transport properties of the Cu-doped manganite La_(0.85)Te_(0.15)Mn_(1-x)Cu_xO_3 (0≤x ≤ 0.20)

摘要

The effect of Cu-doping at Mn-site on structural, magnetic and transport properties in electron-doped manganites La_(0.85)Te_(0.15)Mn_(1-x)Cu_xO_3 (0≤x≤0.20) has been investigated. Based on the analysis of structural parameter variations, the valence state of the Cu ion in Cu-doped manganites is suggested to be +2. All samples undergo the paramagnetic-ferromagnetic (PM-FM) phase transition. The Curie temperature T_c decreases and the transition becomes broader with increasing Cu-doping level, in contrast, the magnetization magnitude of Cu-doping samples at low temperatures increase as x≤0.15. The insulator-metal (I-M) transition moves to lower temperatures with increasing Cu-doping content and disappears as x > 0.1. In addition, the higher temperature resistivity ρ peak in double-peak-like ρ(T) curves observed in no Cu-doping sample is completely suppressed as Cu-doping level x=0.1 and ρ(T) curve only shows single I-M transition at the low temperature well below T_C. The results are discussed according to the change of magnetic exchange interaction caused by Cu-doping.