Superconductivity in type-II Weyl-semimetal WTe2 induced by a normal metal contact

Abstract

WTe2 is a material with rich topological properties: it is a 2D topological insulator as a monolayer and a Weyl-semimetal and higher-order topological insulator (HOTI) in the bulk form. Inducing superconductivity in topological materials is a way to obtain topological superconductivity, which lays at the foundation for many proposals of fault tolerant quantum computing. Here, we demonstrate the emergence of superconductivity at the interface between WTe2 and the normal metal palladium. The superconductivity has a critical temperature of about 1.2 K. By studying the superconductivity in perpendicular magnetic field, we obtain the coherence length and the London penetration depth. These parameters hint to a possible origin of superconductivity due to the formation of flat bands. Furthermore, the critical in-plane magnetic field exceeds the Pauli limit, suggesting a non-trivial nature of the superconducting state.

Positive magnetoresistance and chiral anomaly in exfoliated type-II Weyl semimetal $T_\mathrm{d}$-WTe$_{2}$

“…Another characteristic feature of WTe 2 is the extreme positive transverse magnetoresistance MR ⊥ , reaching values as high as 10 5 % for magnetic fields ∼9 T applied parallel to the c−axis of bulk or thin flakes of WTe 2 in the Fermi liquid phase at T ∼100 mK [50][51][52]. In addition, evidence of topologically protected conducting edge states [53] and flat-band superconductivity in close proximity to Pd [54] and Nb [55] was demonstrated in bulk and few layers WTe 2 flakes, while quantum spin Hall states are shown to exist in mechanically exfoliated monolayer WTe 2 [56]. Most of the reported literature on T d -WTe 2 concerns bulk crystals or mechanically exfoliated flakes.…”

Singular flat bands

“…Due to the suppressed kinetic energy, flat band systems have been considered intriguing in various research areas [1][2][3][4][5][6]. In condensed matter physics, flat bands are considered ideal to study many-body phenomena such as the ferromagnetism [7][8][9][10][11], superconductivity [12][13][14][15][16], and Wigner crystal formation [17][18][19] because the kinetic energy of the carriers in the flat band is quenched and dominated by the electron-electron interaction. In bosonic systems such as the photonic crystals, the realization of the slow light via a flat band has gotten a great attention because it can be applied to enhance the light-matter interaction [20][21][22][23][24][25][26].…”

Formation of tungsten carbide by focused ion beam process: A route to high magnetic field resilient patterned superconducting nanostructures

“…There has been a number of efforts to find exotic superconductors (e.g FFLO, spin-triplet, topological ) in recent past which might compatible with relatively high magnetic field. Several methods including metal intercalation between layers of a material [5,6], applying high pressure, hard and soft tip contact [7][8][9] and interface between two materials [10,11] has been tried for achieving this. In this paper, we point out an emerging class of materials, composed of Ga and a heavy metal carbide, fabricated using FIB which are undoubtedly granular and highly disordered, but with H c2 significantly above the Pauli limit.…”