Magnetic and magnetocaloric properties of Cu-substituted La1−xPbxMnO3 (x∼0.14) single crystals

Abstract

Structural, magnetic, and magnetocaloric properties in perovskite manganites La1−xPbxMn1−y−zCuyO3 (x~0.14, y=0, 0.01, 0.02, z=0.02, 0.08, 0.11) single crystals have been investigated. The Curie temperature TC decreases monotonously with increasing Cu-doping concentration. A sharp downturn in the inverse magnetic susceptibility 1/χm vs T plot at Griffiths temperature TG well above TC was observed for the free-doped sample, which can be attributed to the appearance of spin cluster in the paramagnetic state. The temperature interval between TG and TC decreases with increasing Cu-doping level and almost disappears as Cu concentration reaches 0.02. Large magnetic entropy change ΔSM occurs near TC and ΔSM approaches a maximum value for the sample with Cu-doping level y=0.01. The result can be explained based on the competing effect between the double-exchange interaction and the lattice distortion induced by Cu doping.