Momentum space imaging of Cooper pairing in a half-Dirac-gas topological superconductor (a helical 2D topological superconductor)

Abstract

Superconductivity in Dirac electrons has recently been proposed as a new platform between novel concepts in high-energy and condensed matter physics. It has been proposed that supersymmetry and exotic quasiparticles, both of which remain elusive in particle physics, may be realized as emergent particles in superconducting Dirac electron systems. Using artificially fabricated topological insulator-superconductor heterostructures, we present direct spectroscopic evidence for the existence of Cooper pairing in a half Dirac gas 2D topological superconductor. Our studies reveal that superconductivity in a helical Dirac gas is distinctly different from that of in an ordinary two-dimensional superconductor while considering the spin degrees of freedom of electrons. We further show that the pairing of Dirac electrons can be suppressed by time-reversal symmetry breaking impurities removing the distinction. Our demonstration and momentum-space imaging of Cooper pairing in a half Dirac gas and its magnetic behavior taken together serve as a critically important 2D topological superconductor platform for future testing of novel fundamental physics predictions such as emergent supersymmetry and quantum criticality in topological systems.

Submitted June'14; Accepted to NaturePhysics, to appear AOP (2014)

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• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Engineering a p+ip Superconductor: Comparison of Topological Insulator and Rashba Spin-Orbit Coupled Materials
• Absence of a Proximity Effect in a Topological Insulator on a Cuprate Superconductor: Bi2Se3/Bi2Sr2CaCu2O8
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• Fully gapped superconducting state in Au2Pb: a natural candidate for topological superconductor
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• Topological superconductivity in an ultrathin, magnetically-doped topological insulator proximity coupled to a conventional superconductor
• Non-Quantized Edge Channel Conductance and Zero Conductance Fluctuation in Non-Hermitian Chern Insulators
• Andreev Reflection without Fermi surface alignment in High T${}_c$-Topological heterostructures
• Discovery of the topological surface state in a noncentrosymmetric superconductor BiPd
• Proximity-Induced Superconductivity in a Topological Crystalline Insulator