Effect of thickness on magnetic phase coexistence and electrical transport in Nd0.51Sr0.49MnO3 films |
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Authors: | R Prasad M P Singh P K Siwach A Kaur P Fournier H K Singh |
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Institution: | 1. National Physical Laboratory, Council of Scientific & Industrial Research, Dr. K.S. Krishnan Road, New Delhi, 110012, India 3. Department of Physics and Astrophysics, University of Delhi, Delhi, 110007, India 2. Regroupement québécois sur les matériaux de pointe and Département de Physique, Université de Sherbrooke, Sherbrooke, J1K 2R1, Canada
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Abstract: | We present the impact of the film thickness on the coexistence of various magnetic phases and its link to the magnetoresistance
of Nd0.51Sr0.49MnO3 thin films. These epitaxial films are deposited on LaAlO3 (001) substrates by DC magnetron sputtering. Films with thicknesses of approximately 30 nm are found to be under full compressive
strain while those with thicknesses ∼100 nm and beyond exhibit the presence of both strained and relaxed phases, as evidenced
from X-ray diffraction studies. Both films exhibit multiple magnetic transitions controlled by strong electron correlations
and phase coexistence. These films also display insulator–metal transitions (IMT) and colossal magnetoresistance (CMR) under
moderate magnetic fields. Among the two set of films, only the 30-nm films show a weak signature of charge ordering at T≈50 K. Even at temperatures much lower than the IMT, the 30-nm films show huge magnetoresistance (MR) ∼80%. This suggests
presence of softened charge-ordered insulating (COI) clusters that are transformed into ferromagnetic metallic (FMM) ones
by the external magnetic field. In the 100-nm films, the corresponding MR is suppressed to less than 20%. Our study demonstrates
that the softening of the COI phase is induced by the combined effect of the in-plane compressive strain and a slight reduction
in Sr concentration. |
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