Dimerization-induced topological superconductivity in a Rashba nanowire

Abstract

We analyze the influence of dimerization on the topological phases of a Rashba nanowire proximitized to a superconducting substrate. We find that periodic alternations of the hopping integral and spin-orbit coupling can lead to band inversion, inducing a transition to the topologically nontrivial superconducting phase that hosts Majorana zero-energy modes. This "dimerization-induced topological superconductivity" completely repels the topological phase of the uniform nanowire, whenever they happen to overlap. We provide an analytical justification for this puzzling behavior based on symmetry and parity considerations, and discuss feasible spectroscopic methods for its observation. We also test stability of the topological superconducting phases against electrostatic

Majorana Bound State leakage to impurity in Su-Schrieffer-Heeger-Rashba scenario

“…Then, value of h c depends on model parameters in nontrivial manner and can be determined analytically (more details can be found in Ref. [36]), but still, in the limit of δ → 0, condition (4) remains unchanged.…”

“…Similar analysis of the system can be performed in the momentum space (more details can be found in Ref. [36]). In this case, system can be studied via spin resolved spectral function A kσ (ω) = −1/π Im c kσ |c † kσ .…”

Bulk odd-frequency pairing in the superconducting Su-Schrieffer-Heeger model

“…, is even in momentum k. Note that the intrasublattice odd-ω amplitudes F AA,BB are finite when eitherη or η is nonzero (t and are always assumed to be nonzero), and thus a consequence of the intrinsic sublattice symmetry breaking in the SC SSH model [63,64] but also predicted to appear in other systems such as in buckled quantum spin Hall insulators [55], or in nanowires with Rashba spin-orbit coupling [56]. For η =η = 0 the intrasublattice odd-ω amplitudes vanish.…”

“…For instance, it has been shown that in buckled quantum spin Hall insulators bulk odd-ω correlations appear due to a staggered order parameter but no sign of higher energy gaps in the DOS was reported [55]. Even more interestingly, it has recently been shown in nanowires with Rashba spin-orbit coupling that intrinsic staggered hopping and spin-orbit coupling can induce a topological superconducting phase that completely repels the topological phase of the uniform nanowire [56]. Since these nanowires represent one of the most investigated platforms for one-dimensional topological superconductivity [57][58][59], the reported staggered-induced topological phase is within experimental reach and its fundamental understanding is, therefore, important.…”

“…MZMs have attracted an enormous amount of attention due to their potential use for building topological protected qubits [57][58][59]65]. Interestingly, the SC SSH model captures the main intrinsic staggered properties of systems that are under active investigation [57][58][59]65], such as in buckled quantum spin Hall insulators [55] and in nanowires with Rashba spin-orbit coupling [56]. Therefore, the study of pair correlations in the SC SSH model is expected to provide fundamental understanding of superconducting correlations in these systems.…”