Two-dimensional (2D) van der Waals materials have attracted much attention because they possess unique superconducting phenomena not seen in bulk crystals. Recently, Ta1.6Te, a van der Waals material with a quasicrystalline structure, was reported to exhibit superconductivity below 1 K [1]. Although novel superconducting phenomena originating from quasicrystallinity have been theoretically proposed, experimental studies have remained limited because quasicrystalline superconductors are extremely rare. Therefore, Ta1.6Te provides a promising platform for exploring unconventional superconductivity associated with quasicrystalline structures.

Here, we report the fabrication of Ta1.6Te flakes using a mechanical exfoliation technique. After transferring the flakes onto SiO2/Si substrates, Au/Ti electrodes were patterned on isolated flakes. Similar to the bulk sample [1], resistance of a 50-nm-thick flake increases by 10% with decreasing temperature from 300 K to 4.2 K, suggesting that the quasicrystalline structure is preserved in the flake. With further cooling, the flake shows a sharp superconducting transition at Tc = 0.8 K. A wide vortex-liquid regime, which is often observed in 2D superconductors, has been observed by applying a perpendicular magnetic field. Furthermore, the in-plane Bc2 reaches 4 T at 300 mK. This Bc2 is higher than the reported value for bulk samples [2] and exceeds the Pauli limit. In the presentation, we will discuss how the superconducting properties evolve with decreasing thickness in this quasicrystalline superconductor.

[1]. Y. Tokumoto et al., Nat commun 15, 1529 (2024).

[2]. T. Terashima et al., npj Quantum Mater. 9, 56 (2024).