Transport mechanisms in infinite layer phase compounds grown by molecular beam epitaxy

Abstract

Thin films of infinite layer compounds were prepared by molecular beam epitaxy. Defect layers were incorporated into the structure in order to dope the infinite layer phase. Hole type doping is usually observed. Resistivity measurements show that the conduction mechanisms change gradually with increasing doping level, from activational type to variable range hopping (or a mechanism governed by the Coulomb interaction between localized electrons) and then further to a mechanism related to weak localization which can be described by Δρ=T−S, where the exponent S ranges from 0.5 to 1.5.

Evidence for pseudo‐gap behavior in defect‐doped infinite layer (Ca, Sr)CuO2 thin films

“…Note also that, for a given value of resistivity, the value of T 0 is an order of magnitude less for SrCuO 2 than for Ca 0.3 Sr 0.7 CuO 2 . These dc transport results on infinite layer films differ from previous results for films grown by molecular beam epitaxy, where either 3-D VRH or an unusual ∆ρ ~ T -S behavior was observed [17]. However, the MBE grown samples were reportedly hole-doped whereas the films discussed in this paper are predominantly n-type.…”