High magnetoresistance in La0.5Nd0.15Ca0.25A0.1MnO3 (A = Ca, Li, Na, K) CMR manganites: correlation between their magnetic and electrical properties

Publication date: Available online 4 February 2020Source: Materials Research BulletinAuthor(s): Mukesh Kumar Verma, Narayan Dutt Sharma, Suman Sharma, Nisha Choudhary, Devinder SinghAbstractThe influence of A-site cation disorder of monovalent alkali ions on structural and magneto-transport properties of colossal magnetoresistive (CMR) materials has been reported. All the compounds crystallize in Pbnm space group with orthorhombic symmetry. At low temperature, the samples exhibit a paramagnetic (PM) to ferromagnetic (FM) transition and a semiconductor to metallic one. The variation in both Curie temperature (Tc) and metal-semiconductor transition temperature (TMS) can be explained by the change in Mn4+ content and average A-site cation radius. A decrease in resistivity in the vicinity of TMS has been observed with an increase in the applied magnetic field. The values of Tc are close to TMS, signifying strong correlations between the magnetic and electrical properties. The electrical resistivity data in paramagnetic-semiconducting region (T> TMS) may be described by the adiabatic small polaron hopping (ASPH) model. Maximum magnetoresistance (MR%) has been observed in the vicinity of TMS.Graphical abstractPlots of Magnetoresistance (MR%) as a function of temperature (T) for La0.5Nd0.15Ca0.25A0.1MnO3
Source: Materials Research Bulletin - Category: Materials Science Source Type: research