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Title: Crossover of conduction mechanism in Sr{sub 2}IrO{sub 4} epitaxial thin films

High quality epitaxial Sr{sub 2}IrO{sub 4} thin films with various thicknesses (9–300 nm) have been grown on SrTiO{sub 3} (001) substrates and their electric transport properties have been investigated. All samples showed the expected insulating behavior with a strong resistivity dependence on film thickness, which can be as large as three orders of magnitude at low temperature. A close examination of the transport data revealed interesting crossover behaviors for the conduction mechanism upon variation of thickness and temperature. While Mott variable range hopping (VRH) dominated the transport for films thinner than 85 nm, high temperature (>200 K) thermal activation behavior was observed for films with large thickness (≥85 nm), which was followed by a crossover from Mott to Efros-Shklovskii (ES) VRH in the low temperature range. This low temperature crossover from Mott to ES VRH indicates the presence of a Coulomb gap (∼3 meV). Our results demonstrate the competing and tunable conduction in Sr{sub 2}IrO{sub 4} thin films, which in turn would be helpful for understanding the insulating nature related to strong spin-orbital-coupling of the 5d iridates.
Authors:
 [1] ;  [2] ; ; ; ;  [1] ;  [1] ;  [3]
  1. Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Saale) (Germany)
  2. (China)
  3. (United Kingdom)
Publication Date:
OSTI Identifier:
22310960
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 8; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COUPLING; EPITAXY; IRIDIUM COMPOUNDS; OXYGEN COMPOUNDS; SPIN; STRONTIUM COMPOUNDS; STRONTIUM TITANATES; SUBSTRATES; THICKNESS; THIN FILMS