Current Induced Resistive State in Fe(Se,Te) Superconducting Nanobridges

TL;DR

This study investigates the current-voltage behavior of Fe(Se,Te) superconducting nanostrips, revealing insights into flux pinning, creep flow, and magnetic flux dynamics relevant for superconducting electronics.

Contribution

It provides new estimates of pinning potential and flux dynamics in Fe(Se,Te) nanostrips, highlighting the role of geometry and magnetic interactions in their resistive states.

Findings

Pinning potential and range estimated from transport data.

Classical creep flow model needs magnetic flux interaction for accuracy.

Corners facilitate magnetic flux lines injection, affecting critical current.

Abstract

We study the current-voltage characteristics of Fe(Se,Te) thin films deposited on CaF$_2$ substrates in form of nanostrips (width $w\sim\lambda$, $\lambda$ the London penetration length). In view of a possible application of these materials to superconductive electronics and micro-electronics we focus on transport properties in small magnetic field, the one generated by the bias current. From the characteristics taken at different temperatures we derive estimates for the pinning potential $U$ and the pinning potential range $\delta$. Since the sample lines are very narrow, the classical creep flow model provides a sufficiently accurate interpretation of the data only when the attractive interaction between magnetic flux lines of opposite sign is taken into account. The observed voltages and the induced detriment of the critical current of the nanostrips are compatible with the presence of few tens of magnetic field lines at the equilibrium and a strongly inhomogeneous current density distribution. In particular, we argue that the sharp corners defining the bridge geometry represent points of easy magnetic flux lines injection. The results are relevant for creep flow analysis in superconducting Fe(Se,Te) nanostrips.