Soft-Mode-Phonon-Mediated Unconventional Superconductivity in Monolayer 1T′−WTe2

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

“…An estimate of the superconducting electron density yields quite high value n s = m/µ 0 λ 2 L e 2 ∼ 3 • 10 21 cm −3 , where m ∼ 0.3m e is the effective mass of the electrons in WTe 2 [33]. This value is higher than the typical carrier densities in WTe 2 n ∼ 10 19 cm −3 [33] and corresponds to a density per single layer of n 1L s ∼ 2 • 10 14 cm −2 , which is an order of magnitude higher than the electron density in monolayer WTe 2 with gate induced superconductivity [19,20], but comparable to the predicted optimal charge carrier density [34]. Furthermore, a large superconducting carrier density implies high density of states at the Fermi level g(E F ) ∼ n s /2∆ ∼ 8 • 10 24 cm −3 eV −1 , which is a signature of flat bands.…”

Theory of Glide Symmetry Protected Helical Edge States in WTe$_{2}$ Monolayer

“…Since the first identification of several 1T' TMD's as topological insulators [51], understanding the nature of the d-d band inversion process [90], general phase diagram [81], the role of glide symmetry in strong localization of edge states [75] and the role of edge termination [75,76,78,80] has persisted as a highly challenging task. This similarly applies to the impact of edge roughness on conductance [81], spin dynamics, and anomalous Hall conductivity [89], the role of disorder on edge spin transport [83], the edge magnetoresistance due to orbital moments [91], the possibility of spontaneous magnetization of edge states [74] and gate-activated canted spin texture [86,88], the possible pairing mechanisms and symmetries of the superconducting state [79,82,87,92,93], and the nature of the excitonic insulator [94][95][96][97].…”

“…The plethora of experimental results stimulated a significant body of theoretical work related to analyzing the electronic, spin, and many-body properties of WTe 2 . Various intertwined methods have been used to address the principal electronic structure in this material, including density functional theory [51,53,57,58,62,[69][70][71][72][73][74][75][76][77][78][79][80], tight-binding approaches [75,76,[81][82][83][84], and low-energy k•p models [66,67,[84][85][86][87][88][89]. Remarkably, theoretical models predict a small (if at all) bulk gap in WTe 2 from first principles which is superficially at odds with the rather stable QSH behaviour observed experimentally.…”

Promoted Electronic Coupling of Acoustic Phonon Modes in Doped Semimetallic MoTe2

“…Thus, doping can alter the population of the electronic bands, which renormalizes the EPC and the superconducting states. Search for superconductors in doped 2D materials such as graphene and TMDs has attracted great and ever-increasing interest. − For MoTe 2 , chemical doping was intentionally introduced via methods such as S, Se, , and Re substitutions, which strongly modulate the superconductivity . There is a promoted superconductivity observed through isoelectronic substitution of S/Se with Te in MoTe 2 . − Here the enhancement would be related to the charge transfer from the dopant to the host lattice due to a different electronegativity.…”