A route to high temperature superconductivity in composite systems

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

doi:10.1103/PhysRevB.78.094509

paper

A route to high temperature superconductivity in composite systems

arXiv:0805.3737 · doi:10.1103/PhysRevB.78.094509

Abstract

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, $T_{c} \to T_{M F} \approx Δ_{0} /2$ ? H er e, w es t u d y a s im pl e tw oco m p o n e n t m o d e l in w hi c ha " m e t a l l i c l a y er " w i t h$ Δ_0=0 $i sco u pl e d b y s in g l e - p a r t i c l e t u nn e l in g t o a " p ai r in g l a y er " w i t h$ Δ_0 >0 $b u t z er o p ha ses t i f f n ess . W es h o w t ha t in t h e l imi tt ha tt h e ban d w i d t h o f t h e m e t a l i s m u c h l a r g er t han$ Δ_0 $,$ T_c $o f t h eco m p os i t esy s t e m c an r e a c h t h e u pp er l imi t$ T_c \approxΔ_0/2$.

Journal Ref. added. See also http://physics.aps.org/articles/v1/19