Physical properties of weak-coupling quasiperiodic superconductors
Nayuta Takemori, Ryotaro Arita, Shiro Sakai
Abstract
We numerically study the physical properties of quasiperiodic superconductors with the aim of understanding superconductivity in quasicrystals. Considering the attractive Hubbard model on the Penrose tiling as a simple theoretical model, we calculate various basic superconducting properties and find deviations from the universal values of the Bardeen-Cooper-Schrieffer theory with a constant density-of-states approximation. In particular, we find that the jump of the specific heat at the superconducting transition is about 10%--20% smaller than that universal value, consistent with the experimental results obtained for the superconducting Al-Mg-Zn quasicrystalline alloy. Furthermore, we calculate current-voltage characteristics and find that the current gradually increases with the voltage on the Penrose tiling in contrast to a rapid increase in the periodic system. These distinctions originate from the nontrivial Cooper pairing characteristic of the quasiperiodic system.