Magnetoresistance and magnetocaloric properties of La_0.7Sr_0.3Co_0.95Mn_0.05O₃compound

Abstract

The magnetoresistance and magnetocaloric effects were studied via magnetic and electric properties measurements. The ferromagnetic transition temperature and critical exponents, which are determined by analyzing the Arott plots, to be TC = 190.665K, β = 0.456, γ = 1.0623 and δ = 3.2845, respectively. Although ferro-paramagnetic transition was observed clearly with TC of 190 K but the insulating behaviour is remained in a whole in a temperature region of 5 K up to 300 K. Moreover the negative magnetoresistance shows a shoulder at ∼TC, broadens toward lower temperature and reach maximum of 11.5% at 174 K in applied field of 5 T. This result is explained as due to the competing between ferromagnetic and non-ferromagnetic phases in the sample. The magnetization measurements were performed in a narrow temperature range, close to TC and external magnetic fields up to 4.5T. The adiabatic magnetic entropy changes, ΔS, determined from magnetization data, shows a maximum at TC.