Superconducting Long-Range Proximity Effect through the Atomically Flat Interface of a Bi₂Te₃ Topological Insulator

Abstract

We report on structural and electronic prop-erties of superconducting nano-hybrids made of Pb grown in the ultrahigh vacuum on the atomically clean surface of single crystals of topological Bi 2 Te 3 . In-situ Scanning Tunneling Microscopy and Spectroscopy demonstrated that the resulting network is composed of Pbnanoislands dispersed on the surface and linked together by an amorphous atomic layer of Pb, which wets Bi 2 Te 3 . As a result, the superconducting state of the system is characterized by a thickness-dependent superconducting gap of Pb-islands and by a very unusual positionindependent proximity gap between them. Furthermore, the data analysis and DFT calcu-

Tuning lower dimensional superconductivity with hybridization at a superconducting-semiconducting interface

“…Pb leads to an n -doping of the BP near the interface, pushing the Fermi energy into the intrinsic bulk band gap of the BP and thus this doping quenches any carriers in the BP that can be proximitized. This is in contrast to Pb grown on other narrow band gap semiconductors, such as Bi 2 Te 3 , where the samples are intrinsically n -doped and exhibit a sizeable proximity effect 36 . Finally, we observed a relative difference in the gap structure for ultra-thin films (<≈12 ML), compared to films approximately 30 ML thick.…”

Electronic Structure of Pb Adsorbed Surfaces of Intrinsic Magnetic Topological Insulators

“…Such a behavior of the core levels may be a result of the interaction of Pb atoms with the Bi and Te atoms from the first SL of the IMTI, thus forming the wetting layer. 13,54,55 On the basis of these results, we suppose the following mechanism of Pb atom interaction with the surface of the MTI. Adsorbed Pb atoms bind with Te atoms, and the Pb−Te interaction is expected to be similar to one in well-known PbTe compounds.…”

“…Quantum materials with nontrivial topology have attracted much attention from condensed matter physics researchers over the past few years. Topological insulators (TIs), hosting topologically protected surface states, open routes to a number of peculiar phenomena, such as quantum anomalous Hall and topological magnetoelectric effects, as well as mysterious axion insulator phases. − Furthermore, the contact of a superconductor with a TI surface results in a superconducting proximity effect with the possible creation of Majorana fermions, which is the key for fault-tolerant quantum computing. − …”

Observation of Hidden Parts of Dislocation Loops in Thin Pb Films by Means of Scanning Tunneling Spectroscopy

“…Ultrathin lead (Pb) films and islands appear to be convenient objects for studying quantum-size effects in metallic films in normal and superconducting states by means of transport and Hall measurements , and by STM/STS; − for the investigation of electronic properties in superconducting nanostructures , and superconducting two-dimensional materials, hybrid structure superconductor–ferromagnet, , superconductor–normal metal, , and superconductor–topological insulator; for the investigation of electronic states by means of photoemission electron spectroscopy . We would like to emphasize that the STM/STS technique is usually considered as a method for the testing of electronic properties of the surface due to the exponential decay of both the STM tip and surface wave functions in a tunnel barrier area.…”