Anomalous upper critical field in the quasicrystal superconductor Ta_1.6Te

Recently, Tokumoto et al. have discovered that the quasicrstal Ta_1.6Te superconducts below T_c ~ 1 K (arXiv:2307.10679). This transition temperature is much higher than T_c ~ 0.05 K in the first quasicrystal superconductor, Al-Zn-Mg quasicrystal (Kamiya et al., Nat. Commun. 9, 154 (2018)). This allows detailed investigations of superconducting properties in quasicrystals. In this study, we have performed resistivity and ac magnetic susceptibility measurements on Ta_1.6Te and determined the upper critical field down to 0.04 K (T/T_c ~ 0.04). We show that the temperature dependence of the upper critical field is anomalous.