Spin-orbit coupling and topological superconductivity in full-shell semiconductor-superconductor nanowires (Conference Presentation)

2019 ◽  
Author(s):  
Tudor Stanescu ◽  
Benjamin Woods
Keyword(s):  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Topological Superconductivity

scholarly journals Intrinsic First and Higher-Order Topological Superconductivity in a Doped Topological Insulator

2021 ◽  
Author(s):  
Harley Scammell ◽  
Julian Ingham ◽  
Max Geier ◽  
Tommy Li
Keyword(s):  
Chemical Potential ◽  
Interaction Strength ◽  
Higher Order ◽  
Second Order ◽  
Orbit Coupling ◽  
Order Topology ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Wave State ◽  
Topological Superconductivity

Abstract We explore higher-order topological superconductivity in an artificial Dirac material with intrinsic spin-orbit coupling. A mechanism for superconductivity due to repulsive interactions – pseudospin pairing – has recently been shown to result in higher-order topology in Dirac systems past a minimum chemical potential [1]. Here we apply this theory through microscopic modelling of a superlattice potential imposed on an inversion symmetric hole-doped semiconductor heterostructure, and extend previous work to include the effects of spin-orbit coupling. We find spin-orbit coupling enhances interaction effects, providing an experimental handle to increase the efficiency of the superconducting mechanism. We find that the phase diagram, as a function of chemical potential and interaction strength, contains three superconducting states – a first-order topological p + ip state, a second-order topological spatially modulated p + iτp state, and a second-order topological extended s-wave state, sτ. We calculate the symmetry-based indicators for the p + iτp and sτ states, which prove these states possess second-order topology. Exact diagonalisation results are presented which illustrate the interplay between the boundary physics and spin orbit interaction. We argue that this class of systems offer an experimental platform to engineer and explore first and higher-order topological superconducting states.

scholarly journals Observation of chiral surface excitons in a topological insulator Bi2Se3

2019 ◽  
Vol 116 (10) ◽  
pp. 4006-4011 ◽  
Author(s):  
H.-H. Kung ◽  
A. P. Goyal ◽  
D. L. Maslov ◽  
X. Wang ◽  
A. Lee ◽  
...  
Keyword(s):  
Polarized Light ◽  
Orbit Coupling ◽  
Experimental Investigations ◽  
Composite Particles ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Excitation Energies ◽  
Circularly Polarized Light ◽  
Pl Emission ◽  
Strong Spin

The protected electron states at the boundaries or on the surfaces of topological insulators (TIs) have been the subject of intense theoretical and experimental investigations. Such states are enforced by very strong spin–orbit interaction in solids composed of heavy elements. Here, we study the composite particles—chiral excitons—formed by the Coulomb attraction between electrons and holes residing on the surface of an archetypical 3D TI,Bi2Se3. Photoluminescence (PL) emission arising due to recombination of excitons in conventional semiconductors is usually unpolarized because of scattering by phonons and other degrees of freedom during exciton thermalization. On the contrary, we observe almost perfectly polarization-preserving PL emission from chiral excitons. We demonstrate that the chiral excitons can be optically oriented with circularly polarized light in a broad range of excitation energies, even when the latter deviate from the (apparent) optical band gap by hundreds of millielectronvolts, and that the orientation remains preserved even at room temperature. Based on the dependences of the PL spectra on the energy and polarization of incident photons, we propose that chiral excitons are made from massive holes and massless (Dirac) electrons, both with chiral spin textures enforced by strong spin–orbit coupling. A theoretical model based on this proposal describes quantitatively the experimental observations. The optical orientation of composite particles, the chiral excitons, emerges as a general result of strong spin–orbit coupling in a 2D electron system. Our findings can potentially expand applications of TIs in photonics and optoelectronics.

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