Non‐Centrosymmetric Superconductors on Honeycomb Lattice

Abstract

Non-centrosymmetric topological superconductivity is studied in correlated doped quantum spin-Hall insulators (QSHI) on honeycomb lattice without inversion symmetry where the intrinsic (Kane-Mele) and Rashba spin-orbit couplings can in general exist. The generic topologically non-trivial superconducting phase diagram of the model system is explored. Over a certain parameter range, the parity-mixing superconducting state with co-existing spin-singlet d þ id and spin-triplet p þ ip-wave pairing is found. On a zigzag nanoribbon, the parity-mixing superconducting state shows co-existing helical and chiral Majorana fermions at edges. The relevance of our results for experiments is discussed.

Long-range pairing in monolayer NbSe2 facilitates the emergence of topological superconducting states

“…CN = ±6, ±5, ±4, ±3, ±2, ±1) appearing and the TSC phase regions with CNs = 3 and −2 start to shrink when p A1 is greater than 0.14. The CN displays a sensitive dependence on V z and µ and distributes irregularly between CN = 3 and CN = −2 phases due to long-range pairing, which has also been observed in previous studies [19,20,22,24,[26][27][28][29]. It is notably that the sensitive non-zero CNs appear even under V z = 0 when p A1 is greater than or equal to 0.16 (see figures 2(c)-(f), 3 and 4), suggesting that there may be more intrinsic superconductors (e.g.…”

“…However, recent research progress on topological materials has revealed the sensitivity and richness of the CN phase diagram to variations in the chemical potential (µ), magnetic field (V z ), and superconducting order parameter amplitude [19][20][21][22][23]. Furthermore, there is evidence of a mismatch between the CN and the number of TESs, indicating a deviation from the BBC principle [19,[21][22][23][24][25][26][27][28][29][30]. For example, 2 H b -stacked bilayer transition metal dichalcogenides and bilayer bismuth lattice considering on-site s-wave pairing with Kane-Mele type SOC strength 0.0075 eV or without SOC show the TSC phases with rich and high CNs up to 4 under various µ and superconducting order parameters, which do not strictly always contain the same number of TESs as the CNs [19,25,29].…”

“…Previous studies indicate that, in certain cases, the CNs and TESs of two-dimensional TSC do not always agree with the BBC principle. And pioneering studies show another possible formation mechanism of TSC is originate from the combination of RSOC and unconventional long-range pairing [23,[26][27][28]. However, the effect of long-range pairing on the formation of TSC for monolayer NbSe 2 still lacks and requires comprehensive investigation.…”

Inducing chiral superconductivity on honeycomb lattice systems

“…Highly doped monolayer graphene has been proposed to exhibit these features, with unusual different properties [19][20][21][22]. For discussion and references on this topic, see [23,24].…”