Quenching Current by Flux-Flow Instability in Iron-Chalcogenides Thin Films

Abstract

The stability against quench is one of the main issues to be pursued in a superconducting material, which should be able to perform at very high levels of current densities. Here we focus on the connection between the critical current Ic and the quenching current I â\u88\u97 associated to the so-called Flux-Flow Instability phenomenon, which sets-in as an abrupt transition from the flux flow state to the normal state. To this purpose, we analyze several current-voltage characteristics of three types of Iron-Based thin films, acquired at different temperature and applied magnetic field values. For these samples, we discuss the impact of a possible coexistence of intrinsic electronic mechanisms and extrinsic thermal effects on the quenching current dependence upon the applied magnetic field. The differences between the quenching current and the critical current are also reported in the case of predominant intrinsic mechanisms. Carrying out a comparison with the HTS case, we suggest, which material can be the best tradeoff between maximum operating temperature, higher upper critical field, and stability under high current bias

Angular dependence of vortex instability in a layered superconductor: the case study of Fe(Se,Te) material

“…(iv) P * (θ , H, T ) exhibits a trend similar to V * (θ , H, T ) that points to the fact that self-heating effects are negligible with respect to electronic ones. 18 Additionally, the chosen microbridge geometry based on width less than 20 µm, as well as the bias current pulsed technique based on 2.5 ms pulse width, can support the common origin of the voltage jumps in all magnetic field orientations, thus in agreement with our recent study on the same material performed only in perpendicular field configuration 18,19 , in which the intrinsic electronic nature of such instability has been demonstrated.…”

“…This phenomenon has been extensively studied in low temperature superconductors (LTS) 23,[27][28][29][30] , as well as HTS [31][32][33] , and very recently in IBS 18,19 , too. Its angular dependence has previously been investigated in the BSCCO compound 26 , in which strong anisotropy is expected owing to its highly layered structure, i.e.…”

“…The magnetic field and temperature dependence of this voltage is usually investigated in connection with the nature of the intrinsic or extrinsic mechanisms driving the transition to the normal state. In the Fe(Se,Te) superconductor, we have recently demonstrated that a coexistence of both mechanisms is possible 18 , and that this effect is highly influenced by the microbridge geometry 19 . In Figure 4 the V * (θ ) behavior is displayed at low and high field values, at the three different temperatures 8 K, 10 K, 12 K, in comparison with the corresponding I * (θ ) dependence.…”

“…Indeed a different behavior can be observed for the same Fe(Se,Te) compound grown on different substrates 14 , by tuning the intrinsic/extrinsic pinning mechanisms. In the search for high-performance high-field superconductors, a good candidate can be the Fe(Se,Te) grown on CaF 2 substrate 15 , which shows the lowest anisotropy 16 , a very robust J c ( H ) dependence 17 , and a sufficient stability against quench under relatively high bias currents 18,19 . Additionally, in this compound the study of vortex dynamics has been recently performed at subcritical current values and in self magnetic fields 20 .…”

Flux flow instability as a probe for quasiparticle energy relaxation time in Fe-chalcogenides

“…The study of this switching behaviour in the presence of an external magnetic field can offer the key to handle the material under control or at least to know which are the bias limits for applications [10][11][12][25][26][27]. The influence of several material properties in the Fe(Se,Te) compound on the FFI has been recently studied [7,[27][28][29]. Thus, here we go further to address the issue of evaluating the quasiparticle energy relaxation time τ ε .…”