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Evidence for pseudo‐gap behavior in defect‐doped infinite layer (Ca, Sr)CuO 2 thin films
Author(s) -
Norton David P.,
Chakoumakos Bryan C.,
Budai John D.,
Lowndes Douglas H.
Publication year - 2003
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200301645
Subject(s) - materials science , variable range hopping , condensed matter physics , doping , conductivity , thermal conduction , atmospheric temperature range , quantum tunnelling , electrical resistivity and conductivity , thin film , metal , epitaxy , layer (electronics) , nanotechnology , chemistry , composite material , optoelectronics , metallurgy , electrical engineering , meteorology , physics , engineering
A distinct crossover between the high temperature and low temperature normal state dc transport properties of epitaxial (Ca, Sr)CuO 2 single crystal thin films has been observed. Defect‐doped (Ca, Sr)CuO 2 films with dc conductivity behavior ranging from insulating to metallic‐like were obtained by growing stoichiometric and cation‐deficient material under various film growth conditions. The results indicate that 2D variable‐range hopping is the dominant transport mechanism at low temperatures. The high temperature behavior depends on the magnitude of the conductivity, resulting in either activated conduction or a ln ρ ∼ 1/ T 1/2 dependence that is reminiscent of thermally‐activated tunneling in a granular metal/insulator matrix. The distinct crossover in behavior suggests the possibility of gap formation in the temperature range 150–200 K.