Evidence of mobile carriers with charge-ordering gap in epitaxial Pr0.625Ca0.375MnO3 thin films

Singh, Udai Raj ; Chaudhuri, S. ; Dutta, Anirban ; Budhani, R. C. ; Gupta, Anjan K. (2010) Evidence of mobile carriers with charge-ordering gap in epitaxial Pr0.625Ca0.375MnO3 thin films Physical Review B, 81 (15). pp. 5120-5124. ISSN 0163-1829

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Official URL: http://prb.aps.org/abstract/PRB/v81/i15/e155120

Related URL: http://dx.doi.org/10.1103/PhysRevB.81.155120

Abstract

Epitaxial thin films of charge-ordered Pr0.625Ca0.375MnO3 have been studied using variable-temperature scanning tunneling microscopy and spectroscopy. The as-grown films were found to be granular while the annealed films show atomic terraces at all temperatures and are found to be electronically homogeneous in 78-300 k temperature range. At high temperatures (Tgt;TCO≈230 k) the local tunnel spectra of the annealed films show a depression in the density of states (DOS) near Fermi energy (EF) implying a pseudogap with a significant DOS at EF. The gap feature becomes more robust with cooling with a sharp jump in DOS at EF at TCO and with a gap value of ~0.3 eV at 78 k;. At low temperatures we find a small but finite DOS at EF indicative of some delocalized carriers in the charge-ordered phase together with an energy gap. This is consistent with bulk transport, which shows weakening of the activation gap with cooling below 200 k, and indicates the presence of two types of carriers at low temperatures.

Item Type:Article
Source:Copyright of this article belongs to American Physical Society.
ID Code:5506
Deposited On:19 Oct 2010 12:05
Last Modified:16 May 2016 16:00

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