[Seminar] "Exploring novel superconducting properties in few-layer Td-MoTe2" by Dr. Taro Wakamura

Title

Exploring novel superconducting properties in few-layer T_d-MoTe₂

Speaker

Dr. Taro Wakamura / NTT Basic Research Laboratories

Zoom: https://oist.zoom.us/j/92164277280?pwd=EtClSiF0mouaCFNocZaC4b5hz3GTRa.1&from=addon

Abstract

Two-dimensional materials exhibit unique properties particularly in the thin limit. Td-MoTe2 is a transition metal dichalcogenide known as a type-II Weyl semimetal in the bulk form. Since it becomes superconducting at low temperatures, Td-MoTe2 is a potential candidate for a topological superconductor. In addition, unconventional s+--wave has been proposed as a pairing symmetry. However, the low critical temperature (Tc) around 100 mK makes it difficult to elucidate its unique superconducting properties and to obtain signitures of topological superconductivity. Recently, significant enhancement of Tc has been reported by decreasing the thickness of Td-MoTe2, whose origin remains unclear. While there exist many studies on electronic properties of bulk Td-MoTe2, few-layer Td-MoTe2 has scarcely been explored due to the instability of the material in atomosphere and experimental difficulties in the device fabrication.

In this talk, focusing on superconducting transport properties, I will first show the thickness dependence of superconducting properties in few-layer Td-MoTe2, and discuss a possible pairing symmetry by comparing the experimental data with the first principles calculation results. Exploiting enhanced superconductivity and the low crystal symmetry of Td-MoTe2, we successfully demonstrated the giant superconducting nonreciprocal transport driven by ratchet-like motion of superconducting vortices, and the gate modulation of nonreciprocal signals by reducing the sample thicknesses [1, 2].

[1] T. Wakamura et al., “Gate-tunable giant superconducting nonreciprocal transport in few-layer Td-MoTe2” Phys. Rev. Research. 6, 013132 (2024).

[2] T. Wakamura et al., “Superconducting properties of few-layer Td-MoTe2”, submitted.