Abstract Body

Quasicrystal is a solid with a long-range ordered but aperiodic structure of atoms. Reflecting the aperiodic structure, electrons on a quasicrystal are distributed nonuniformly. This distribution can be changed by changing temperature, pressure, and external fields, distinct from periodic crystals with a uniform electron distribution, as well as from amorphous solids with a statistically uniform distribution. This applies to quasicrystalline superconductors, too, which were discovered in experiments recently [1,2]. In these superconductors, both the electron density and superconducting order parameters are distributed nonuniformly [3] and the superconducting properties depend on such spatial distributions. Thus, the spatial distributions in quasicrystals can be a novel knob to control superconducting properties.

In this talk, I will present our numerical studies on quasicrystalline superconductors, showing how the spatial distributions depend on the average electron filling and electron interactions [3]. I will then show that the superconducting properties of quasicrystals deviate from those of periodic crystals due to their spatial inhomogeneity [4,5]. I will also introduce a measure, called hyperuniformity [6], to evaluate the "regularity" of the inhomogeneous distributions [7], and discuss its relevance to the superconducting properties.

References

1. K. Kamiya et al., Nature Commun. 9, 154 (2018).
2. Y. Tokumoto et al., arXiv:2307.10679.
3. S. Sakai, N. Takemori, A. Koga, and R. Arita, Phys. Rev. B 95, 024509 (2017);
4. N. Takemori, R. Arita, and S. Sakai, Phys. Rev. B 102, 115108 (2020)
5. T. Fukushima, N. Takemori, S. Sakai, M. Ichioka, and A. Jagannathan, J. Phys.: Conf. Ser. 2461, 012014 (2023)
6. S. Torquato, Phys. Rep. 745, 1 (2018).
7. S. Sakai, R. Arita, and T. Ohtsuki, Phys. Rev. B 105, 054202 (2022).

Acknowledgment

This work is supported by JSPS KAKENHI No. 22H04603 and 23H04528.