Pairing-dependent superconductivity gap and nonholonomic Andreev reflection in Weyl semimetal/Weyl superconductor heterojunctions

Abstract

Pairing-dependent superconductivity gap and nonholonomic Andreev reflection in Weyl semimetal/Weyl superconductor heterojunctions" (2018). Faculty of Engineering and Information Sciences -Papers: Part B. 1604. Pairing-dependent superconductivity gap and nonholonomic Andreev reflection in Pairing-dependent superconductivity gap and nonholonomic Andreev reflection in Weyl semimetal/Weyl superconductor heterojunctions Weyl semimetal/Weyl superconductor heterojunctions Abstract AbstractWe study superconductivity states mediated by the BCS and Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairings in superconducting Weyl semimetals. It is found that a mixture of BCS and FFLO pairings results in a distinctive double-gap structure for superconducting states. With a heterojunction of a Weyl semimetal and a superconducting Weyl semimetal, we demonstrate the nonholonomic Andreev reflection and show that the intra-and internode Andreev reflections increase at the edges of the effective gap. The influence of interface potentials on the Andreev reflections is investigated. The conductance spectra arising from the mixed superconducting pairings is also analyzed. . Pairing-dependent superconductivity gap and nonholonomic Andreev reflection in Weyl semimetal/Weyl superconductor heterojunctions. PhysicalWe study superconductivity states mediated by the BCS and Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairings in superconducting Weyl semimetals. It is found that a mixture of BCS and FFLO pairings results in a distinctive double-gap structure for superconducting states. With a heterojunction of a Weyl semimetal and a superconducting Weyl semimetal, we demonstrate the nonholonomic Andreev reflection and show that the intraand internode Andreev reflections increase at the edges of the effective gap. The influence of interface potentials on the Andreev reflections is investigated. The conductance spectra arising from the mixed superconducting pairings is also analyzed.

Equilibrium current in a Weyl-semimetal - superconductor heterostructure

“…where the gap d τ (k y , k z ) was defined in Eq. (46). For the µ-derivative of the k z -resolved current I y (k z ) we then find a "regular" contribution and a "singular" contribution, which follows from the derivative of the discontinuity of the step function s(φ) at φ = π (mod 2π),…”

“…One prominent type of such heterostructures is the Josephson junction (SNS-heterostructure), which has been extensively studied theoretically exploring the influence of various types of superconducting pairing mechanisms [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35], and has also been realized experimentally [19,[36][37][38][39][40]. Other examples of similar heterostructures are NS-type [17,20,[41][42][43][44][45][46][47][48][49][50][51], and NSN-type [52][53][54][55][56] heterostructures.…”

Chiral anomaly induced oscillations in the Josephson current in Weyl semimetals

“…The Josephson effect is one of the powerful tools to identify the superconducting pairing. Recently, the Andreev reflection 39,40 and Josephson effect [41][42][43][44][45][46] in a WSM have been theoretically investigated in several works. It has been predicted that at the interface between a timereversal breaking WSM and a conventional s-wave superconductor, the singlet pairing requires the intra-node Andreev reflection due to the spin-momentum locking of Weyl fermions [42][43][44] .…”

Resolving different pairing states in Weyl superconductors through the single-particle spectrum

“…Apart from the natural materials, it was also proposed that superconductivity may be realized through doping, the proximity effect, or applying a magnetic field. Physical properties of Weyl superconductors and their potential applications have attracted broad interest in the past few years [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38].…”