| Both experimental and theoretical studies on high-Tc cuprate superconductors show a high pairing scale in the underdoped (UD) region and stronger coherence of carriers in the overdoped (OD) region, while the critical temperature of both regions is lower than at optimal doping. By connecting the two doping regions in a multilayer geometry, the proximity of the strong pairing interaction from the UD region may produce stronger superconductivity in the OD region. We investigate the possibility of enhanced superconductivity in superlattices(SL's) of cuprates by studying Hubbard and t-J models of SL’s made up of UD and OD cuprate layers using layer extensions of the cellular dynamical mean-field theory and the dynamic cluster approximation as well as the slave-boson mean-field (SBMF) theory. We find that the superconducting (SC) order parameter is indeed increased in UD/OD SL’s as compared to its value in the uniform system. For some combinations of dopings, the SC order parameter is found to become larger than its largest value in the uniform system. Furthermore, the SBMF calculation predicts a transition temperature in the SL that exceeds the maximum Tc in the uniform system. These results suggest that “higher-Tc” superconductivity may indeed be realized in SL’s of cuprates. This work was done by Satoshi Okamoto in collaboration with Thomas A. Maier at Computer Science and Mathematics Division and Center for Nanophase Materials Sciences, ORNL. Phys. Rev. Lett. 101, 156401 (2008). |
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