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Thursday, September 22, 2011
12:30 PM - 2:00 PM
Theoretical Division Conference Room, TA-3, Building 123, Room 121.

Quantum Lunch

Non-additive effect of superconductivity suppression by thickness reduction and magnetic Gd impurities in amorphous MoGe films

Andrey Rogachev
University of Utah

The effect of magnetic Gd atoms on superconducting properties of amorphous Mo-Ge films with the thickness in the range 1-50 nm was systematically studied. The critical temperature, Tc, of undoped films was found to drop from 6.5 to 1 K with decreasing thickness. Despite this reduction, the critical volume concentration of magnetic impurities, 6.5 at. % of Gd, remains independent on thickness of superconducting films. The strength of the magnetic pair-breaker (measured as an initial linear slop of Tc vs. Gd percent dependence) monotonically decreases with decreasing film thickness and becomes zero for the superconducting films with Tc =1 K. Thus, the suppression of superconductivity by reducing film thickness and by magnetic impurities are observed to be non-additive processes in amorphous Mo-Ge alloy. The anomalous behavior is likely related to the spatially inhomogeneous distribution of the order parameter.

Host: Dima Mozyrsky, T-4 , 7-9657