The isotope effect in a superlattice of quantum stripes

We have calculated the isotope effect coefficient and the critical temperature in a particular superconducting heterostructure formed by a bidimensional (2D) superlattice of metallic quantum stripes. We model the superlattice with a 2D free electron gas confined in a ID periodic potential barrier. Within the BCS theory we calculate the shape resonance for the critical temperature and the isotope coefficient as a function of the chemical potential. The results provide a good description of the anomalous behavior of the isotope coefficient in La2-xSrxCuO4 as a function of doping with a sharp peak alpha similar to 0.8 in the underdoped regime and a rapid drop to alpha similar to 0.2 at 0.125 holes per copper site.