New insight into enhanced superconductivity in metals near the metal-insulator transition.
We have studied the transport properties of disordered WSi films near the metal/insulator transition (MIT) and we have also reviewed the data for several other disordered materials near their MIT. In all cases, we found the presence of enhanced superconductivity. We constructed a superconductivity "phase diagram" (i.e., T(c) versus sigma) for each system, which reveals a striking correlation: In all cases, T(c) values are significantly enhanced only for samples whose conductivities lie within a narrow range on the metallic side of, and moderately near, the MIT. We present a heuristic model to explain this phenomenon.
Osofsky
M S
MS
Naval Research Laboratory, Washington, DC 20375, USA.
Soulen
R J
RJ
Claassen
J H
JH
Trotter
G
G
Kim
H
H
Horwitz
J S
JS