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Continuous transition from weakly localized regime to strong localization regime in Nd0.7La0.3NiO3 films.
Bisht, Ravindra Singh; Daptary, Gopi Nath; Bid, Aveek; Raychaudhuri, A K.
Afiliación
  • Bisht RS; Department of Condensed Matter Physics and Material Sciences, S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India.
J Phys Condens Matter ; 31(14): 145603, 2019 Apr 10.
Article en En | MEDLINE | ID: mdl-30734721
We report an investigation of metal-insulator transition (MIT) using conductivity and magnetoconductance (MC) measurements down to 0.3 K in Nd0.7La0.3NiO3 films grown on crystalline substrates of LaAlO3 (LAO), SrTiO3 (STO), and NdGaO3 (NGO) by pulsed laser deposition. The film grown on LAO experiences a compressive strain and shows metallic behavior with the onset of a weak resistivity upturn below 2 K which is linked to the onset of weak localization contribution. Films grown on STO and NGO show a cross-over from a positive temperature coefficient (PTC) resistance regime to negative temperature coefficient (NTC) resistance regime at definite temperatures. We establish that a cross-over from PTC to NTC on cooling does not necessarily constitute a MIT because the extrapolated conductivity at zero temperature [Formula: see text] though small (<10 S cm-1) is finite, signaling the existence of a bad metallic state and absence of an activated transport. The value of [Formula: see text] for films grown on NGO is reduced by a factor of 40 compared to that for films grown on STO. We show that a combination of certain physical factors makes substituted nickelate (that are known to exhibit first-order Mott type transition), undergo a continuous transition as seen in systems undergoing disorder/composition driven Anderson transition. The MC measurement also supports the above observation and shows that at low temperatures, there exists a positive MC that arises from the quantum interference which co-exists with a spin-related negative MC that becomes progressively stronger as the electrons approach a strongly localized state in the film grown on NGO.

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: J Phys Condens Matter Asunto de la revista: BIOFISICA Año: 2019 Tipo del documento: Article País de afiliación: India Pais de publicación: Reino Unido

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: J Phys Condens Matter Asunto de la revista: BIOFISICA Año: 2019 Tipo del documento: Article País de afiliación: India Pais de publicación: Reino Unido