Topological protection in hybrid semiconductor-superconductor materials largely relies on the electronic properties. This paper presents growth and characterization of epitaxial InAs${}_{1\ensuremath{-}x}$Sb${}_{x}$/Al nanowires where both composition crystal structure semiconductor is varied. Among findings are a strong spin-orbit coupling at intermediate compositions, large effective $g$ factors, induced hard-gap superconductivity with zincblende wurtzite structure, signatures topological

Nanowires can serve as flexible substrates for hybrid epitaxial growth on selected facets, allowing the design of heterostructures with complex material combinations and geometries. In this work we report epitaxy freestanding vapor–liquid–solid grown in-plane selective area semiconductor–ferromagnetic insulator–superconductor (InAs/EuS/Al) nanowire heterostructures. We study crystal matching wurtzite zinc-blende InAs/rock-salt EuS interfaces well rock-salt EuS/face-centered cubic Al...

Uniform, defect-free crystal interfaces and surfaces are crucial ingredients for realizing high-performance nanoscale devices. A pertinent example is that advances in gate-tunable topological superconductivity using semiconductor/superconductor electronic devices currently built on the hard proximity-induced superconducting gap obtained from epitaxial indium arsenide/aluminum heterostructures. Fabrication of requires selective etch processes; these exist only InAs/Al hybrids, precluding use...

Coupling individual atoms fundamentally changes the state of matter: electrons bound to atomic cores become delocalized turning an insulating a metallic one. A chain could lead more exotic states if tunneling takes place via superconducting vacuum and can induce topologically protected excitations like Majorana or parafermions. Although coupling single atom superconductor is well studied, hybridization two sites with tunability was not reported yet. The peculiar Bardeen-Cooper-Schrieffer...

Abstract Hybrid nanostructures consisting of two parallel InAs nanowires connected by an epitaxially grown superconductor (SC) shell recently became available. Due to the defect-free SC-semiconductor interface and quasi-one-dimensional channels being close by, these platforms can be utilized spatially separate entangled pairs electrons using quantum dots (QD) in so-called Cooper pair splitting (CPS) process. The minimized distance between QDs overcomes limitations single-wire-based...

Understanding the microscopic origin of gate-controlled supercurrent (GCS) in superconducting nanobridges is crucial for engineering switches suitable a variety electronic applications. The GCS controversial, and various mechanisms have been proposed to explain it. In this work, we investigated Ta layer deposited on surface InAs nanowires. Comparison between switching current distributions at opposite gate polarities dependence two side gates with different nanowire-gate spacings shows that...

Hybrid superconductor-semiconductor devices offer highly tunable platforms, potentially suitable for quantum technology applications, that have been intensively studied in the past decade. Here we establish measurements of superconductor-to-normal transition originating from Joule heating provide a powerful spectroscopical tool to characterize such hybrid devices. Concretely, apply this technique junctions full-shell Al-InAs nanowires Little-Parks regime and obtain detailed information each...

Andreev spin qubits are a new qubit platform that merges superconductivity with semiconductor physics. The mechanisms dominating observed energy relaxation remain unidentified. We report here on three steps taken to address these questions in an InAs nanowire weak link. First, we designed microwave readout circuit tuned be directly sensitive the spin-dependent inductance of link so higher orbital states not necessary for -- this resulted larger windows parameter space which state properties...

Josephson junctions formed in semiconductor nanowires host Andreev bound states and serve as a physical platform to realize qubits tuned by electrostatic gating. With the state being confined nanoscale weak link, it couples circuit-QED architecture via state-dependent supercurrent flowing through link. Thus, increasing this coupling strength is crucial challenge for architecture. Here, we demonstrate fabrication microwave characterization of an InAs nanowire link embedded superconducting...

Gate-controlled supercurrent (GCS) in superconducting nanobridges has recently attracted attention as a means to create switches. Despite the clear advantages for applications, microscopic mechanism of this effect is still under debate. In work, we realize GCS first time highly crystalline superconductor epitaxially grown on an InAs nanowire. We show that epitaxial Al layer can be switched normal state by applying ≃±23 V bottom gate insulated from nanowire hBN layer. Our extensive study...

The observation of the gate-controlled supercurrent (GCS) effect in superconducting nanostructures increased hopes for realizing a equivalent semiconductor field-effect transistors. However, recent works attribute this to various leakage-based scenarios, giving rise debate on its origin. A proper understanding microscopic process underlying GCS and relevant time scales would be beneficial evaluate possible applications. In work, we observed gate-induced two-level fluctuations between state...

Epitaxially connected nanowires allow for the design of electron transport experiments and applications beyond standard two terminal device geometries. In this Letter, we present growth methods three distinct types wurtzite structured InAs nanocrosses via vapor–liquid–solid mechanism. Two use conventional nanowire arrays as a 6-fold hexagonal basis growing single crystal nanocrosses. A third method uses 2-fold cubic symmetry (100) substrates to form well-defined coherent inclusions zinc...

We report MBE synthesis of InAs/vanadium hybrid nanowires. The vanadium was deposited without breaking ultra-high vacuum after InAs nanowire growth, minimizing any effect oxidation and contamination at the interface between two materials. investigated four different substrate temperatures during deposition, ranging from -150 °C to 250 °C. structural relation depended on deposition temperature. three lower temperature depositions gave shells with a polycrystalline, granular morphology highest...

Any device exposed to ambient conditions will be prone oxidation. This may of particular importance for semiconductor nanowires because the high surface-to-volume ratio and only little is known about consequences oxidation these systems. Here, we study properties indium arsenide which were locally oxidized using a focused laser beam. Polarization dependent micro-Raman measurements confirmed presence crystalline arsenic, transmission electron microscopy diffraction showed oxide. The surface...

Abstract Little–Parks oscillations of a hollow superconducting cylinder are interest for flux-driven topological superconductivity in single Rashba nanowires. The typically symmetric the orientation applied magnetic flux. Using double InAs nanowires coated by an epitaxial Al shell which, despite non-centro-symmetric geometry, behaves effectively as one cylinder, we demonstrate that small misalignment parallel field with respect to axis can produce field-asymmetric oscillations. These...

We characterize parallel double quantum dot Josephson junctions based on closely spaced nanowires bridged by in-situ deposited superconductors. The behavior occurs despite the proximity of two and potential risk nanowire clamping during growth. By tuning charge filling lead couplings, we map out Yu-Shiba-Rusinov phase diagram. Our quasi-independent two-wire hybrids show promise for realization exotic topological phases.

Semiconducting nanowires grown by quasi-van-der-Waals epitaxy on graphite flakes are a new class of hybrid materials that hold promise for scalable nanostructured devices within opto-electronics. Here we report high aspect ratio and stacking fault free Ag-seeded InAs exfoliated molecular beam epitaxy. Ag catalyzes the nanowire growth selectively not underlying substrates. This allows easy transfer flexible with as-grown ensembles to arbitrary substrates micro-needle manipulator. Besides...

We compare the spin-orbit interaction (SOI) in InAs nanowires grown conventional $\ensuremath{\langle}0001\ensuremath{\rangle}$ crystal direction and perpendicular $\ensuremath{\langle}01\overline{1}0\ensuremath{\rangle}$ direction. It is theoretically shown that, for individual transverse modes, intrinsic contribution due to bulk inversion asymmetry of vanishes wires but remains finite $\ensuremath{\langle}01\overline{1}0\ensuremath{\rangle}$. Experimental scattering lengths extracted from...

Abstract Parallel 1D semiconductor channels connected by a superconducting strip constitute the core platform in several recent quantum device proposals that rely, for example, on Andreev processes or topological effects. In order to realize these proposals, actual material systems must have high crystalline purity, and coupling between different elements should be controllable terms of their interfaces geometry. A strategy synthesizing double InAs nanowires vapor‐liquid‐solid mechanism...

Understanding heating and cooling mechanisms in mesoscopic superconductor–semiconductor devices is crucial for their application quantum technologies. Owing to poor thermal conductivity, effects can drive superconducting-to-normal transitions even at low bias, observed as sharp conductance dips through the loss of Andreev excess currents. Tracking such across magnetic field, cryostat temperature, applied microwave power allows us uncover bottlenecks different parts a device. By applying this...

Hybrid semiconductor-superconductor nanowires have emerged as a cornerstone in modern quantum devices. Integrating such into hybrid devices typically requires extensive postgrowth processing which may affect device performance unfavorably. Here, we present technique for situ shadowing superconductors on and compare the structural electronic properties of Al junctions formed by versus etching. Based transmission electron microscopy, find that typical etching procedures lead to atomic-scale...

Abstract The strong coupling of a superconductor to spinful quantum dot results in Yu–Shiba–Rusinov discrete subgap excitations. In isolation and at zero temperature, the excitations are sharp resonances. transport experiments, however, they show as broad differential conductance peaks. Here we obtain lineshape peaks their temperature dependence superconductor–quantum dot–metal nanowire-based devices. Unexpectedly, find that shift energy with magnitude sign depending on ground state parity...

We characterize in-situ grown parallel nanowires bridged by a superconducting island. The magnetic-field and temperature dependence of Coulomb blockade peaks measured across different pairs nanowire ends are consistent with sub-gap state extended over the hybrid parallel-nanowire Being gate-tunable, accessible multiple terminals free quasiparticle poisoning, these show promise for implementation several proposals that rely on platforms.