Properties of Interfaces and Surfaces in Non-centrosymmetric Superconductors

Eschrig, Matthias; Iniotakis, Christian; Tanaka, Yukio

doi:10.1007/978-3-642-24624-1_11

Cited by 15 publications

(31 citation statements)

References 98 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[8][9][10][11][12][13][14] For instance, a fully gapped NCS with nontrivial topology supports linearly dispersing helical Majorana modes at its boundary. 8,9,[15][16][17][18][19][20] In three-dimensional systems, the stability of these Majorana surface states is protected by an integer (Z) topological invariant, i.e., the three-dimensional winding number, 9,15 whereas in two-dimensional systems a binary (Z 2 ) topological number guarantees the robustness of the edge modes. 8,17,[21][22][23] Remarkably, topologically protected zero-energy boundary modes also occur in NCSs with line nodes.…”

Section: Introductionmentioning

confidence: 99%

“…Apart from these twodimensional surface flat bands, certain NCSs also support zero-energy boundary states that form one-dimensional open arcs in the surface BZ, connecting the projection of two nodal rings. 10,20,[25][26][27][28][29] Moreover, it has recently been reported that Majorana surface states can occur at time-reversal-invariant momenta of the surface BZ, 9,14 even if the superconductor is not fully gapped in the bulk.…”

Section: Introductionmentioning

confidence: 99%

“…5 For the study of surface phenomena in NCSs it is thus important to explicitly account for the strong SOC, 13,29,[39][40][41] a subtlety that has been overlooked in many previous works. 10,20,[25][26][27][28] The main aim of this paper is to provide a comprehensive classification of the topological features of three-dimensional nodal NCSs. In particular, we demonstrate that the presence of certain inversion-type symmetries gives rise to additional topological features of the gap line nodes.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Types of topological surface states in nodal noncentrosymmetric superconductors

2012

View full text Add to dashboard Cite

Nodal noncentrosymmetric superconductors have topologically nontrivial properties manifested by protected zero-energy surface states. Specifically, it was recently found that zero-energy surface flat bands of topological origin appear at their surface. We show that the presence of certain inversion-type lattice symmetries can give rise to additional topological features of the gap nodes, resulting in surface states forming one-dimensional arcs connecting the projections of two nodal rings. In addition, we demonstrate that Majorana surface states can appear at time-reversal-invariant momenta of the surface Brillouin zone, even when the system is not fully gapped in the bulk. Within a continuum theory we derive the topological invariants that protect these different types of zero-energy surface states. We independently derive general conditions for the existence of zero-energy surface bound states using the complementary quasiclassical scattering theory, explicitly taking into account the effects of spin-orbit splitting of the bands. We compute surface bound-state spectra for various crystal point-group symmetries and orbital-angular-momentum pairing states. Finally, we examine the signatures of the arc surface states and of the zero-energy surface flat bands in tunneling-conductance spectra and dicuss how topological phase transitions in noncentrosymmetric superconductors could be observed in experiments.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Types of topological surface states in nodal noncentrosymmetric superconductors

2012

View full text Add to dashboard Cite

show abstract

“…Andreev surface states A non-zero quantized value of any of the three topological numbers (4), (5) and (6) implies the existence of zero-energy Andreev surface states. First of all, in fully gapped phases with topologically non-trivial character there appear linearly dispersing Majorana surface modes [3,[15][16][17]. In order to understand the appearance of zeroenergy Andreev surface states in the gapless phases, we now make use of the topological invariant N L with a cleverly chosen loop L. Let us consider Eq.…”

mentioning

confidence: 99%

“…Refs. [16,17]). Remarkably, this is a surface Ma- jorana mode in a gapless (nodal) superconducting phase [19].…”

mentioning

confidence: 99%

Topological phases and surface flat bands in superconductors without inversion symmetry

2011

View full text Add to dashboard Cite

We examine different topological phases in three-dimensional non-centrosymmetric superconductors with time-reversal symmetry by using three different types of topological invariants. Due to the bulk boundary correspondence, a non-zero value of any of these topological numbers indicates the appearance of zero-energy Andreev surface states. We find that some of these boundary modes in nodal superconducting phases are dispersionless, i.e., they form a topologically protected flat band. The region where the zero-energy flat band appears in the surface Brillouin zone is determined by the projection of the nodal lines in the bulk onto the surface. These dispersionless Andreev surface bound states have many observable consequences, in particular, a zerobias conductance peak in tunneling measurements. We also find that in the gapless phase there appear Majorana surface modes at time-reversal invariant momenta which are protected by a Z2 topological invariant. 03.65.Vf, 74.55.+v, 74.45.+c, 73.20.Fz The hallmark of topological insulators and superconductors (SCs) is the existence of topologically protected conducting boundary modes. The recent experimental observation of these edge and surface states in spin-orbit induced Z 2 topological insulators in two and three dimensions [1], respectively, has lead to a surge of interest and excitement [2]. An exhaustive classification of topologically protected boundary modes occurring in gapped free fermion systems in terms of symmetry and spatial dimension was given in Refs. [3][4][5]. Interestingly, this classification scheme, which is known as the "periodic table" of topological insulators and SCs, predicts a three dimensional (3D) topological SC which satisfies time-reversal symmetry, but breaks spin-rotation symmetry. Indeed, the B phase of 3 He is one example of this so-called "class DIII" topological superfluid, whose different topological sectors can be distinguished by an integer topological invariant. Recent transverse acoustic impedance measurements in 3 He-B confirmed the existence of the predicted surface Majorana bound state [6].However, finding an electronic analog of the superfluid B phase of 3 He remains an outstanding challenge. In this paper we argue that some of the 3D non-centrosymmetric SCs might be examples of electronic topological SCs in symmetry class DIII [7]. We analyze the topological phase diagram of these systems and demonstrate quite generally that adjacent to fully gapped topological phases there exist non-trivial gapless superconducting phases with topologically protected nodal lines (rings). To characterize these gapless lines we introduce a set of topological invariants and show that, due to the bulkboundary correspondence, the presence of topologically stable nodal rings implies the appearance of dispersionless zeroenergy Andreev surface states. These topologically protected surface flat bands manifest themselves in scanning tunneling spectroscopy (STS) as a zero bias conductance peak, a feature which could be used as an experimental signatu...

show abstract

Spin-polarized supercurrents for spintronics: a review of current progress

2015

Self Cite

View full text Add to dashboard Cite

During the past 15 years a new field has emerged, which combines superconductivity and spintronics, with the goal to pave a way for new types of devices for applications combining the virtues of both by offering the possibility of long-range spin-polarized supercurrents. Such supercurrents constitute a fruitful basis for the study of fundamental physics as they combine macroscopic quantum coherence with microscopic exchange interactions, spin selectivity, and spin transport. This report follows recent developments in the controlled creation of long-range equal-spin triplet supercurrents in ferromagnets and its contribution to spintronics. The mutual proximity-induced modification of order in superconductor-ferromagnet hybrid structures introduces in a natural way such evasive phenomena as triplet superconductivity, odd-frequency pairing, Fulde-Ferrell-Larkin-Ovchinnikov pairing, long-range equal-spin supercurrents, [Formula: see text]-Josephson junctions, as well as long-range magnetic proximity effects. All these effects were rather exotic before 2000, when improvements in nanofabrication and materials control allowed for a new quality of hybrid structures. Guided by pioneering theoretical studies, experimental progress evolved rapidly, and since 2010 triplet supercurrents are routinely produced and observed. We have entered a new stage of studying new phases of matter previously out of our reach, and of merging the hitherto disparate fields of superconductivity and spintronics to a new research direction: super-spintronics.

show abstract

Properties of Interfaces and Surfaces in Non-centrosymmetric Superconductors

Cited by 15 publications

References 98 publications

Types of topological surface states in nodal noncentrosymmetric superconductors

Types of topological surface states in nodal noncentrosymmetric superconductors

Topological phases and surface flat bands in superconductors without inversion symmetry

Spin-polarized supercurrents for spintronics: a review of current progress

Contact Info

Product

Resources

About