arXiv subjects

A. Kotsovolou

Publications and source records attributed to A. Kotsovolou.

2 recordsLinked to original sources

arXiv2026

Superconducting properties of lifted-off Niobium nanowires

Hybrid superconductor/semiconductor devices play a crucial role in advancing quantum science and technology by merging the properties of superconductors and semiconductors. To operate these devices at high temperature, Niobium could substitute the widespread aluminum as superconducting element. Niobium devices show the best superconducting properties when shaped by etching, but this technique is often incompatible with semiconductors and two-dimensional materials. Our work investigates the influence of oxygen diffusion on the superconducting transition of Nb nanowires fabricated by lift-off technique. To this scope, we fabricate and measure Nb devices of different width (W) and thickness (t). By using the Berezinskii-Kosterlitz-Thouless (BKT) model for charge transport, we demonstrate that our nanowires behave as two-dimensional superconductors regardless of W and t. While the normal-state transition temperature (TN) remains constant with decreasing W, the temperature of the fully superconducting state (TS) decreases. Thus, the superconducting transition width (δTC) increases as W shrinks, due to oxygen diffusion from the lithography resist occurring during deposition. These insights provide essential knowledge for optimizing Nb-based hybrid quantum devices, paving the way for operating temperatures above 2 K and contributing to the development of next-generation quantum technologies.

cond-mat.supr-con↗

arXiv2021

An Investigation of radiative proton-capture reactions in the Cd-In mass region

The reaction network in the neutron-deficient part of the nuclear chart around $A \sim 100$ contains several nuclei of importance to astrophysical processes, such as the p-process. This work reports on the results from recent experimental studies of the radiative proton-capture reactions $^{112,114}\mathrm{Cd}(p,γ)^{113,115}\mathrm{In}$. Experimental cross sections for the reactions have been measured for proton beam energies residing inside the respective Gamow windows for each reaction, using isotopically enriched $^{112}\mathrm{Cd}$ and $^{114}\mathrm{Cd}$ targets. Two different techniques, the in-beam $γ$-ray spectroscopy and the activation method have been employed, with the latter considered necessary to account for the presence of low-lying isomers in $^{113}\mathrm{In}$ ($E_γ \approx 392$~keV, $t_{1/2} \approx 100$~min), and $^{115}\mathrm{In}$ ($E_γ \approx 336$~keV, $t_{1/2} \approx 4.5$~h). Following the measurement of the total reaction cross sections, the astrophysical S factors have been additionally deduced. The experimental results are compared with Hauser-Feshbach theoretical calculations carried out with the most recent version of TALYS. The results are discussed in terms of their significance to the various parameters entering the models.

nucl-ex↗