A route to high temperature superconductivity in composite systems

Berg, E.; Orgad, D.; Kivelson, S. A.

A route to high temperature superconductivity in composite systems

Authors

Berg, E.

Orgad, D.

Kivelson, S. A.

Description

Apparently, some form of local superconducting pairing persists to temperatures well above the maximum observed $T_c$ in underdoped cuprates, \textit{i.e.} $T_c$ is suppressed due to the small phase stiffness. With this in mind, we consider the following question -- Given a system with a high pairing scale $Δ_0 $ but with $T_c$ reduced by phase fluctuations, can one design a composite system in which $T_c$ approaches its mean-field value, $T_c\to T_{MF}\approx Δ_0/2\$? Here, we study a simple two component model in which a "metallic layer" with $Δ_0=0$ is coupled by single-particle tunneling to a "pairing layer" with $Δ_0 >0 $ but zero phase stiffness. We show that in the limit that the bandwidth of the metal is much larger than $Δ_0$, $T_c$ of the composite system can reach the upper limit $T_c \approxΔ_0/2$.
Journal Ref. added. See also http://physics.aps.org/articles/v1/19