Nature of correlated polaron hopping mechanism in A-site cation disorder Nd0.7−xLaxSr0.3MnO3 (x = 0.0, 0.1, 0.2 and 0.3) manganites

Vadnala, Sudharshan and Asthana, Saket and Srivastava, Neeta B (2020) Nature of correlated polaron hopping mechanism in A-site cation disorder Nd0.7−xLaxSr0.3MnO3 (x = 0.0, 0.1, 0.2 and 0.3) manganites. Applied Physics A. pp. 126-155. ISSN 0947-8396

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Abstract

The structural, transport and magnetic properties of Nd0.7−xLaxSr0.3MnO3 (for x = 0.0, 0.1, 0.2, 0.3) manganite prepared by solid-state route were investigated. All the samples are exhibiting distorted orthorhombic perovskite structure. Lattice parameters and bond angles are increasing with an increase in La concentration. The electrical resistivity ρ(T → 0) and ρ(Tc), both are decreasing with substitution of La (x = 0.0, 0.1, 0.2, 0.3) and the presence of an external magnetic field giving rise to the colossal magnetoresistance (CMR) effect. The temperature-dependent transport nature has been explored with a correlated polaron hopping mechanism based on the Holstein Hamiltonian model. This model is very well concurring with our experimental results and it is further addressing the widely known transition from the low-temperature metallic to the localized polaron hopping conductivity at high temperature. Furthermore, the spin-order temperature (Tc) and the atomic-order temperature (Tca) both are increasing with La substitution. The present analysis shows that the correlated polaron hopping model describes the transport properties of La-substituted Nd0.7−xLaxSr0.3MnO3 samples.

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