Magneto-transport properties of La0.75Ca0.15Sr0.1MnO3 with YBa2Cu3O7–δ addition

We report the structural, magnetic, electrical and magentoresistance properties of (La 0.75 Ca 0.15 Sr 0.1 MnO 3 ) 1− x (YBa 2 Cu 3 O 7−δ ) x (with x =0, 0.025, 0.05, 0.075, 0.1, 0.2, and 0.3) composites synthesized through sol–gel method. The powder X-ray diffraction patterns indicate no evidence of reaction between La 0.75 Ca 0.15 Sr 0.1 MnO 3 (LCSMO) and YBa 2 Cu 3 O 7−δ (YBCO). The addition of YBCO induces a reduction of the total magnetization while the Curie temperature remains almost constant (∼312 K). The behavior of the electrical resistivity evolves differently depending on the doping level. Above the paramagnetic–insulating transition temperature the resistivity data were best-fitted by using the adiabatic small polaron and variable range hopping models. Ferromagnetic–metallic regime in the composites seems to emanate from the electron–phonon or/and electron–magnon scattering processes. With increasing the YBCO doping content (until x =0.1), the positive magnetoresistance (MR) of YBCO phase dominates the negative MR of LCSMO one, which gives rise to the decreasing of MR of the composites.