arXiv subjects

E. V. Shpagina

Publications and source records attributed to E. V. Shpagina.

4 recordsLinked to original sources

arXiv2026

Thermal bottleneck in a freely suspended superconducting island on InAs nanowire

We investigate the heat balance in superconducting islands (S-islands) formed in epitaxial Al/InAs nanowires (NWs) freely suspended above the substrate. We employ a Joule spectroscopy approach, which traces the superconductor-normal transition in the S-island mediated by heating of the neighboring InAs NW segments via transport current. The temperature of the surrounding 3He bath is varied with nearby mesoscopic heaters and controlled with the NW Johnson noise thermometry. The experiment reveals a substantial thermal relaxation bottleneck associated with the cooling via surrounding 3He, which gives rise to phonon heating in the S-island. Our results uncover the role of environmental cooling in non-equilibrium experiments in S-islands in NW devices.

cond-mat.mes-hall↗

arXiv2025

Superconducting bistability in floating Al islands of hybrid Al/InAs nanowires

We investigate a non-equilibrium aspect of the current-driven superconducting-normal phase transition in floating Al islands of epitaxial full-shell Al/InAs nanowires. Within a transition region discontinuous voltage jumps and hysteretic behaviour of the I-V characteristics are observed, associated with the destruction and recovery of the superconducting order parameter in the island. The strength of the two features varies strongly in different devices in a mutually correlated way and can be suppressed by a small magnetic field. Numerical calculation explains this behaviour in terms of a tiny non-equilibrium correction to the electronic energy distribution at low energies. The experiment demonstrates a critical failure of a two-temperature non-equilibrium model of the superconductor-normal transition in floating islands of hybrid nanowire devices.

cond-mat.mes-hall↗

arXiv2024

Fate of the superconducting state in floating islands of hybrid nanowire devices

We investigate the impact of transport current on the superconducting order parameter in superconducting islands in full-shell epitaxial Al-InAs nanowires. Depending on a device layout, the suppression of superconductivity occurs in three fundamentally different ways -- by a critical current in the case of superconducting reservoirs and by a critical voltage or by a critical Joule power in the case of normal reservoirs. In the latter case, the collapse of the superconducting state depends on the ratio of the dwell time and the electron-phonon relaxation time of quasiparticles in the island. For low resistive and high resistive coupling to the reservoirs, respectively, the relaxation-free regime and the strong electron-phonon relaxation regime are realized. Our results shed light on potential shortcomings of finite-bias transport spectroscopy in floating islands.

cond-mat.mes-hall↗

arXiv2021

Thermal conductance and non-equilibrium superconductivity in a diffusive NSN wire probed by shot noise

We investigate diffusive nanowire-based structures with two normal terminals on the sides and a central superconducting island in the middle, which is either grounded or floating. Using a semiclassical calculation we demonstrate that both device layouts permit a quantitative measurement of the energy-dependent sub-gap thermal conductance $G_\mathrm{th}$ from the spectral density of the current noise. In the floating case this goal is achieved without the need to contact the superconductor provided the device is asymmetric, that may be attractive from the experimental point of view. In addition, we observe that the shot noise in the floating case is sensitive to a well-known effect of non-equilibrium suppression and bistability of the superconducting gap. Our calculations are directly applicable to the multi-mode case and can serve as a starting point to understand the shot noise response in open one dimensional Majorana device.

cond-mat.mes-hall↗