Degradation of topological surface state by nonmagnetic S doping in SrxBi2Se3

Abstract

Research on possible topological superconductivity has grown rapidly over the past several years, from fundamental studies to the development of next generation technologies. Recently, it has been reported that the SrxBi2Se3 exhibits superconductivity with topological surface state, making this compound a promising candidate for investigating possible topological superconductivity. However, whether or not the topological surface state is robust against impurities is not clear in this system. Here we report a detailed investigation on the lattice structure, electronic and magnetic properties, as well as the topological superconducting properties of SrxBi2Se3−ySy samples. It is found that the superconducting transition temperature keeps nearly unchanged in all samples, despite of a gradual decrease of the superconducting shielding volume fraction with increasing S doping content. Meanwhile, the Shubnikov-de Hass oscillation results of the SrxBi2Se3−ySy samples reveal that the topological surface states are destroyed in S doped samples, suggesting the topological character is degraded by nonmagnetic dopants.

Structural distortion behind the nematic superconductivity in Sr x Bi2Se3

“…In single-component uniform system both mobilities are governed by the same scattering processes and μ SdH /μ Hall is less than 2 [32]. μ SdH /μ Hall ∼2.5 ratio, observed in our case, as well as in [10,15] implies that for some reason resistivity is too high. Indeed, if grain boundaries are responsible for this high resistivity, whereas low-disorder crystallites provide intensive magnetooscillations starting from relatively low fields, this high μ SdH /μ Hall ratio is naturally explained.…”

“…The most studied topological insulator material, Bi 2 Se 3 , becomes superconductive being doped with Sr, Nb or Cu, with T c around 3 K and H c2 about a few Tesla [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Nature of this superconductivity (topological or not) is in the focus of discussion during the last few years.…”

A Markov theoretic description of stacking-disordered aperiodic crystals including ice and opaline silica

“…A fruitful direction of future theoretical work may be to extend the theory so far explored to crystals composed of infinitely many kinds of layer, which could be applied to a crystal composed of layers that are identical to their immediate predecessor up to some rotation, translation, change in curvature, or shift orthogonal to the basal plane, which takes one of infinitely many values. Such crystals possess so-called turbostratic disorder, and include a range of materials including smectites (Ufer et al, 2008(Ufer et al, , 2009, carbon blacks (Shi, 1993;Zhou et al, 2014) and possibly n-layer graphene, a novel material that has captured the attention of the nanoscience community (Razado-Colambo et al, 2016;Huang et al, 2017). Such an extension of existing theory may be achievable by replacing the transition matrix (an operator on a finite-dimensional vector space) with a transition operator on an infinite-dimensional Banach space.…”

A hidden Markov model for describing turbostratic disorder applied to carbon blacks and graphene

“…Aside from carbon blacks, it is now well known (Huang et al, 2017;Razado-Colambo et al, 2016) that layers of graphene can be stacked on top of one another with a rotation between them adopting an angle 2 ½À 6 ; 6 , taking one of an uncountable infinity of values. The rotation can adopt any angle, but the sixfold rotational symmetry of graphene allows us to work in the restricted range 2 ½À 6 ; 6 .…”

“…1. The electronic properties of Moiré graphene are rich and exotic, and have become the subject of a huge international research effort; see, for example, Huang et al (2017), Razado-Colambo et al (2016), Brown et al (2012), Havener et al (2012) or Cao et al (2018), where the most recent authors identified a magic angle where a twisted bilayer becomes a superconductor. Though the Moiré angles are importantly distinct from the other rotation angles, the latter are still of interest; in fact Bistritzer & MacDonald (2011) have remarked that for all other angles , a twisted bilayer has no unit cell, but has instead a quasi-periodic structure with its own set of properties.…”