Recent photoemission and transport experiments have found that superconductivity can be enhanced (and the transition temperature Tc elevated) when nanoscale striped inhomogeneities are present in the electronic structure of the cuprate high-temperature superconductors. To understand this behavior, we have carried out dynamic cluster quantum Monte Carlo simulations of a striped Hubbard model, a coarse-grained description of the low-energy physics of the cuprate materials. Consistent with these experiments, these simulations show that that the superconducting transition temperature is enhanced when stripes of a certain periodicity and strength are present, and that it is caused by an enhancement of the pairing interaction coming from the antiferromagnetically correlated hole-weak regions. Large-scale dynamic cluster quantum Monte Carlo simulations, performed on leadership-class computing platforms in the National Center for Computational Sciences at ORNL, won the Gordon Bell prize in November 2008, awarded for the highest performing scientific computation.
Over the past three years, building on the success of the dynamic cluster approximation (Gordon Bell prize) and utilizing and developing new theoretical/computational capabilities (such as new quantum Monte Carlo algorithms), as part of the CNMS science program we have:
- Evolved focus from cuprate-based superconductors to the new iron-based superconductors
- Obtained fundamental understanding of nature of superconductivity in Hubbard models of cuprate and pnictides
- Identified structural and electronic characteristics that would enable a room-temperature transition superconductors