Enhancement of the superconducting transition temperature in   La2-xSrxCuO4 bilayers: Role of pairing and phase stiffness
  The superconducting transition temperature, Tc, of bilayers comprising underdoped La2-xSrxCuO4 films capped by a thin heavily overdoped metallic La1.65Sr0.35CuO4 layer, is found to increase with respect to Tc of the bare underdoped films. The highest Tc is achieved for x = 0.12, close to the 'anomalous' 1/8 doping level, and exceeds that of the optimally-doped bare film. Our data suggest that the enhanced superconductivity is confined to the interface between the layers. We attribute the effect to a combination of the high pairing scale in the underdoped layer with an enhanced phase stiffness induced by the overdoped film. 
Ofer Yuli, Itay Asulin, Leonid Iomin, Gad Koren, Oded Millo, and Dror   Orgad