Robust topological phase in proximitized core–shell nanowires coupled to multiple superconductors

Stãnescu, Tudor D.; Sitek, Anna; Manolescu, Andrei

doi:10.3762/bjnano.9.142

Cited by 16 publications

(18 citation statements)

References 67 publications

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“…The gapless region in the upper right corner of Figs. 3, A and B, of the main text is due m J = ±2 states fulfilling condition (28). If condition (28) is not satisfied and the number of bands at the Fermi levels is even, the system can be gapped -see, for instance, panels (b) and (c) in Fig.…”

Section: Effect Of Higher Mj States On the Gapmentioning

confidence: 99%

Flux-induced topological superconductivity in full-shell nanowires

Vaitiekėnas

Winkler

Heck

et al. 2020

Science

218

238

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We present a novel route to realizing topological superconductivity using magnetic flux applied to a full superconducting shell surrounding a semiconducting nanowire core. In the destructive Little-Parks regime, reentrant regions of superconductivity are associated with integer number of phase windings in the shell. Tunneling into the core reveals a hard induced gap near zero applied flux, corresponding to zero phase winding, and a gapped region with a discrete zero-energy state around one applied flux quantum, Φ0 = h/2e, corresponding to 2π phase winding. Theoretical analysis indicates that in the presence of radial spin-orbit coupling in the semiconductor, the winding of the superconducting phase can induce a transition to a topological phase supporting Majorana zero modes. Realistic modeling shows a topological phase persisting over a wide range of parameters, and reproduces experimental tunneling conductance data. Further measurements of Coulomb blockade peak spacing around one flux quantum in full-shell nanowire islands shows exponentially decreasing deviation from 1e periodicity with device length, consistent with Majorana modes at the ends of the nanowire. arXiv:2003.13177v1 [cond-mat.mes-hall]

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Section: Effect Of Higher Mj States On the Gapmentioning

confidence: 99%

Flux-induced topological superconductivity in full-shell nanowires

Vaitiekėnas

Winkler

Heck

et al. 2020

Science

218

238

View full text Add to dashboard Cite

show abstract

“…However, unless the QMS appears exactly at zero energy, the transient oscillations are suppressed, and the Fourier peak corresponding to the 'smooth enough' case is considerably more pronounced. It is also possible that more than one Majorana or quasi-Majorana pair coexist leading to multiple in-gap resonances of both zero and nonzero energies [82,83]. In these situations we would expect a rich transient signature with oscillations between different Majorana (and quasi-Majorana) states reflecting all the intricacies of the in-gap level structure.…”

Section: Comparison Between Mzms and Qmsmentioning

confidence: 99%

Distinguishing Majorana zero modes from impurity states through time-resolved transport

et al. 2019

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We study time-resolved charge transport in a superconducting nanowire using time-dependent Landauer-Büttiker theory. We find that the steady-state Majorana zero-bias conductance peak emerges transiently accompanied by characteristic oscillations after a bias-voltage quench. These oscillations are suppressed for trivial impurity states (IS) that otherwise show a similar steady-state signal as the Majorana zero mode (MZM). In addition, we find that Andreev bound states or quasi-Majorana states (QMS) in the topologically trivial bulk phase can give rise to a zero-bias conductance peak, also retaining the transient properties of the MZM. Our results imply that (1) time-resolved transport may be used as a probe to distinguish between the topological MZM and trivial IS; and (2) the QMS mimic the transient signatures of the topological MZMs.

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“…Typically, the spatial profile is obtained with simple one-dimensional models. 19 The transverse profile has so far been obtained numerically for effective models: of core-shell nanowires in cylindrical 20,21 and prismatic, 22,23 and of full nanowires in hexagonal 24 geometries.…”

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confidence: 99%

Transverse profile and three-dimensional spin canting of a Majorana state in carbon nanotubes

et al. 2019

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The full spatial 3D profile of Majorana bound states (MBS) in a nanowire-like setup featuring a semiconducting carbon nanotube (CNT) as the central element is discussed. By atomic tightbinding calculations we show that the chiral nature of the CNT lattice is imprinted in the MBS wave function which has a helical structure, anisotropic in the transverse direction. The local spin canting angle displays a similar spiral pattern, varying around the CNT circumference. We reconstruct the intricate 3D profile of the MBS wave function analytically, using an effective low energy Hamiltonian accounting both for the electronic spin and valley degrees of freedom of the CNT. In our model the four components of the Majorana spinor are related by the three symmetries of our Bogoliubov-de Gennes (BdG) Hamiltonian, reducing the number of independent components to one. A Fourier transform analysis uncovers the presence of three contributions to the MBS, one from the Γ-point and one from each of the Fermi points, with further complexity added by the presence of two valley states in each contribution.Over the past decade Majorana fermions have been of great interest in condensed matter physics. Under special conditions they arise as quasiparticles in superconductors, 1 where they are zero energy eigenstates of the Bogoliubov-de Gennes (BdG) Hamiltonian and of the particle-hole symmetry operator. Theoretically such quasiparticles were predicted to appear in the elusive one-dimensional p-wave superconductors; 2 but it is also possible to engineer s-wave systems in such a way that they mimic p-wave superconductivity. 3 The most popular setup is based on semiconducting nanowires with large spin-orbit interaction and large g-factor in contact with a superconductor, which induces superconducting proximity correlations in the wire. 4,5 Although the experiments are by now very advanced, 6 a definite proof that the reported signatures 7-10 are really due to the topologically non trivial Majorana bound states (MBS) is still missing. Thus, recent proposals have suggested to use local probes to infer exclusive properties of a MBS, such as its nonlocality and its peculiar spin canting structure, [11][12][13][14][15][16] or the maximal electron-hole content of the Majorana spinor. 17,18 However, in order to exclude spurious effects, local experiments can be truly useful only if the spatial profile of the MBS is known with sufficient accuracy. This is very difficult to achieve for the case of the semiconducting nanowires, since their diameter of a few tens of nanometers and their length of several hundreds of nanometers do not allow for a microscopic calculation of the MBS wavefunction. Typically, the spatial profile is obtained with simple one-dimensional models. 19 The transverse profile has so far been obtained numerically for effective models: of core-shell nanowires in cylindrical 20,21 and prismatic, 22,23 and of full nanowires in hexagonal 24 geometries.In this work we show that the spatial profile of MBS can be derived analytically with go...

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Robust topological phase in proximitized core–shell nanowires coupled to multiple superconductors

Cited by 16 publications

References 67 publications

Flux-induced topological superconductivity in full-shell nanowires

Flux-induced topological superconductivity in full-shell nanowires

Distinguishing Majorana zero modes from impurity states through time-resolved transport

Transverse profile and three-dimensional spin canting of a Majorana state in carbon nanotubes

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