25 research outputs found
Type-II Ising Pairing in Few-Layer Stanene
Spin-orbit coupling has proven indispensable in realizing topological
materials and more recently Ising pairing in two-dimensional superconductors.
This pairing mechanism relies on inversion symmetry breaking and sustains
anomalously large in-plane polarizing magnetic fields whose upper limit is
expected to diverge at low temperatures, although experimental demonstration of
this has remained elusive due to the required fields. In this work, the
recently discovered superconductor few-layer stanene, i.e. epitaxially strained
-Sn, is shown to exhibit a new type of Ising pairing between carriers
residing in bands with different orbital indices near the -point. The
bands are split as a result of spin-orbit locking without the participation of
inversion symmetry breaking. The in-plane upper critical field is strongly
enhanced at ultra-low temperature and reveals the sought for upturn
Experimental observation of Dirac-like surface states and topological phase transition in PbSnTe(111) films
The surface of a topological crystalline insulator (TCI) carries an even
number of Dirac cones protected by crystalline symmetry. We epitaxially grew
high quality PbSnTe(111) films and investigated the TCI phase by
in-situ angle-resolved photoemission spectroscopy. PbSnTe(111)
films undergo a topological phase transition from trivial insulator to TCI via
increasing the Sn/Pb ratio, accompanied by a crossover from n-type to p-type
doping. In addition, a hybridization gap is opened in the surface states when
the thickness of film is reduced to the two-dimensional limit. The work
demonstrates an approach to manipulating the topological properties of TCI,
which is of importance for future fundamental research and applications based
on TCI
Type-II Ising pairing in few-layer stanene
Spin-orbit coupling has proven indispensable in the realization of topological materials and, more recently, Ising pairing in two-dimensional superconductors. This pairing mechanism relies on inversion symmetry–breaking and sustains anomalously large in-plane polarizing magnetic fields whose upper limit is predicted to diverge at low temperatures. Here, we show that the recently discovered superconductor few-layer stanene, epitaxially strained gray tin (α-Sn), exhibits a distinct type of Ising pairing between carriers residing in bands with different orbital indices near the Γ-point. The bands are split as a result of spin-orbit locking without the participation of inversion symmetry–breaking. The in-plane upper critical field is strongly enhanced at ultralow temperature and reveals the predicted upturn
Hard superconducting gap in PbTe nanowires
Semiconductor nanowires coupled to a superconductor provide a powerful
testbed for quantum device physics such as Majorana zero modes and gate-tunable
hybrid qubits. The performance of these quantum devices heavily relies on the
quality of the induced superconducting gap. A hard gap, evident as vanishing
subgap conductance in tunneling spectroscopy, is both necessary and desired.
Previously, a hard gap has been achieved and extensively studied in III-V
semiconductor nanowires (InAs and InSb). In this study, we present the
observation of a hard superconducting gap in PbTe nanowires coupled to a
superconductor Pb. The gap size () is 1 meV (maximally 1.3 meV
in one device). Additionally, subgap Andreev bound states can also be created
and controlled through gate tuning. Tuning a device into the open regime can
reveal Andreev enhancement of the subgap conductance, suggesting a remarkable
transparent superconductor-semiconductor interface, with a transparency of
0.96. These results pave the way for diverse superconducting quantum
devices based on PbTe nanowires