arXiv subjects

Xue-Si Li

Publications and source records attributed to Xue-Si Li.

3 recordsLinked to original sources

arXiv2020

Topological properties of the dimerized Kitaev chain with long-range hopping and pairing terms

We investigate the topological properties of a dimerized Kitaev chain with long-range interactions, including the intercell hopping and superconducting pairing terms. It is found that even only when the intercell hopping term appears, the size of the energy gap, the proportion of topological phases, and the topological phase transition can be modulated. The notable result is that they lead to a new Kitaev-like phase featured by the twofold-degenerated Majorana zero-energy edge states. Next in the presence of the intercell superconducting pairing term, this kind of Majorana phase can be magnified. This work provides new proposals to realize the twofold degenerated Majorana modes based on the intercell hopping and superconducting pairing terms of the dimerized Kitaev chain.

cond-mat.mes-hall↗

arXiv2019

${\cal PT}$ symmetry of the Su-Schrieffer-Heeger model with imaginary boundary potentials and next-nearest-neighboring coupling

By introducing the next-nearest-neighboring (NNN) intersite coupling, we investigate the eigenenergies of the $\cal PT$-symmetric non-Hermitian Su-Schrieffer-Heeger (SSH) model with two conjugated imaginary potentials at the end sites. It is found that with the strengthening of NNN coupling, the particle-hole symmetry is destroyed. As a result, the bonding band is first narrowed and then undergoes the top-bottom reversal followed by the its width's increase, whereas the antibonding band is widened monotonously. In this process, the topological state extends into the topologically-trivial region, and its energy departs from the energy zero point, accompanied by the emergence of one new topological state in this region. All these results give rise to the complication of the topological properties and the manner of $\cal PT$-symmetry breaking. It can be concluded that the NNN coupling takes important effects to the change of the topological properties of the non-Hermitian SSH system.

cond-mat.mes-hall↗

arXiv2018

Double Andreev reflections and double electron transmissions in a normal-superconductor-normal junction based on type-II Weyl semimetal

We study the quantum transport behavior of a normal-superconductor-normal junction based on type-II Weyl semimetal, which is arranged in the tilting direction of the Weyl semimetal. We find that both the crossed Andreev reflection and normal reflection are forbidden, while there will be double Andreev reflections and double electron transmissions for the incident electron from the semimetal side. Andreev reflections and transmissions occur both in the retro and specular directions simultaneously, symmetric about the normal of the interface but with different amplitudes, depending on the angle and energy of incident electrons. These transport processes make the junction here quite different from that based on the normal metal or graphene. In addition, the differential conductance is studied for experimental signatures. We find that the conductance is almost unaffected by the chemical potential and it is enhanced with increasing junction length.

cond-mat.mes-hall↗