Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.
For more information, contact Diego Dalvit.
To add your name to the Quantum Lunch email list, contact Ellie Vigil

Thursday, September 22, 2011
12:30 PM - 2:00 PM

Speaker: Andrey Rogachev (University of Utah)

Technical Host: Dima Mozyrsky

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

Abstract
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.