Impact of potassium substitution on structural, magnetic, magnetocaloric and magneto-transport properties of Nd0.6Sr0.4−xKxMnO3 (0.0 ≤x≤ 0.2) manganite.

A detailed study of structural, magnetic, magnetocaloric and magneto-transport properties of Nd_0.6Sr_0.4−xK_xMnO₃ (x = 0.0, 0.1 and 0.2) manganite, prepared using the sol–gel process, has been performed. All compounds are pure single phase crystallized in the orthorhombic system with Pnma space group. Rietveld analysis reveals the dependence of structural properties upon the monovalent substitution rate. The nanometric size determined through Debye–Scherrer formula is validated by SEM micrographs. Magnetization curves as a function of temperature exhibit a clear ferromagnetic to paramagnetic (FM-PM) phase transition at Curie temperature (T_c) which is found to decrease with increasing K fraction x. Large relative cooling power (RCP) value standing for about 50% of that noticed in pure Gd under magnetic field of 5 T is achieved for x = 0.0 compound, indicating its potential application in the cooling fields. Electrical resistivity curves as a function of temperature exhibit a metal–semiconductor (M-Sc) transition for all samples. The magnetoresistance (MR) ratio reaches its highest value for x = 0.2 sample under an external magnetic field of 2 T making this material a promising magnetoresistive sensor used in a wide range of industrial applications. Significant values of thermal coefficient of resistivity (TCR) are noted under zero external magnetic field giving these materials a potential application for the infrared (IR) and bolometric detectors. [ABSTRACT FROM AUTHOR]