Transport, magnetic, internal friction, and Young's modulus in the Y-doped manganites La 0.9−xY xTe 0.1MnO 3

Abstract

The resistivity, magnetization, internal friction, and Young's modulus for the polycrystalline samples La 0.9− x Y x Te 0.1MnO 3 ( x = 0 , 0.05, 0.10 and 0.15) have been investigated. All samples have rhombohedral crystallographic structure with the space group R 3 ¯ C . The Curie temperature T C of the studied samples decreases with increasing Y-doping level. For the samples with x = 0 , 0.05 and 0.10, the temperature dependence of the resistivity ρ( T) exhibits two metal–insulator transitions (MIT) at T p1 (which is close to its Curie temperature T C) and T p2 (which is below T p1). When the doping level to 0.15, these two MIT temperatures are suppressed and an upturn at low temperatures below T* is observed from the ρ( T) curve. A change of Young's modulus E is observed in the vicinity of T C accompanied by a broad peak of the internal friction Q −1 for all studied samples. The values of the relative Young's modulus Δ E increase with increasing Y-doping level at the low temperatures. These results are discussed in terms of the local Jahn–Teller (JT) distortion by the substitution of smaller Y 3+ ions for larger La 3+ ions and the increased bending of the Mn–O–Mn bond with decreasing the average ionic radius of the A-site element 〈 r A 〉 and the tolerance factor t, resulting in the narrowing of the bandwidth, the decrease of the mobility of e g electrons and the weakening of double-exchange (DE) interaction.