Abstract:We report the first experimental observation of the quenching of the superconducting state in current-voltage characteristics of an iron-based superconductor, namely, in FeSeTe thin films. Based on available theoretical models, our analysis suggests the presence of an intrinsic flux-flow electronic instability along with non-negligible extrinsic thermal effects. The coexistence and competition of these two mechanisms classify the observed instability as halfway between those of low-temperature and of high-temp… Show more
“…(2) and (3). Then, for current-driven measurements the nonlinear resistive part of the CVC exhibits a jump-like voltage rise 16) and (24). The thick black curves at α = 0 reproduce the BS results [16] without pinning.…”
The effect of pinning on self-heating triggering the Larkin-Ovchinnikov (LO) flux-flow instability (FFI) in superconducting thin films is theoretically investigated. The problem is considered relying upon the Bezuglyj-Shklovskij (BS) generalization of the LO theory, accounting for a finite heat removal from the quasiparticles at temperature T * to the bath at temperature T0. The FFI critical parameters, namely the current density j * , the electric field E * , the power density P * , and the vortex velocity v * are calculated and graphically analyzed as functions of the magnetic field and the pinning strength. With increasing pinning strength at a fixed magnetic field value E * decreases, j * increases, while P * and T * remain practically constant. Vortex pinning may hence be the cause for eventual discrepancies between experiments on superconductors with strong pinning and the generalized LO and BS results.
“…(2) and (3). Then, for current-driven measurements the nonlinear resistive part of the CVC exhibits a jump-like voltage rise 16) and (24). The thick black curves at α = 0 reproduce the BS results [16] without pinning.…”
The effect of pinning on self-heating triggering the Larkin-Ovchinnikov (LO) flux-flow instability (FFI) in superconducting thin films is theoretically investigated. The problem is considered relying upon the Bezuglyj-Shklovskij (BS) generalization of the LO theory, accounting for a finite heat removal from the quasiparticles at temperature T * to the bath at temperature T0. The FFI critical parameters, namely the current density j * , the electric field E * , the power density P * , and the vortex velocity v * are calculated and graphically analyzed as functions of the magnetic field and the pinning strength. With increasing pinning strength at a fixed magnetic field value E * decreases, j * increases, while P * and T * remain practically constant. Vortex pinning may hence be the cause for eventual discrepancies between experiments on superconductors with strong pinning and the generalized LO and BS results.
“…6. This physical quantity is usually a measure of the heating effects, since a thermal runway rather than an intrinsic dominant trigger could affect the instability mechanism 18 . The angular variation of P * follows strictly the angular variation of V *, by analogy with the BSCCO case 26 , but in our case it is mainly due to the blindness of I * to the same angle variation.Figure 6The dissipated electric power at the instability point as a function of the angle normalized to the values corresponding to the perpendicular direction of the external field.…”
Section: Resultsmentioning
confidence: 99%
“…Additionally, in this compound the study of vortex dynamics has been recently performed at subcritical current values and in self magnetic fields 20 . However, in the presence of an external applied magnetic field and at high vortex velocities, we have established the intrinsic nature of a quenching mechanism of the superconducting state, known as flux flow instability, occurring above J c in the current driven transition to the normal state 18 . Moreover, several dynamical vortex flow instabilities have been also analyzed in superconductors exhibiting a negative differential resistance 21 .…”
Section: Introductionmentioning
confidence: 92%
“…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 .…”
Anisotropy effects on flux pinning and flux flow are strongly effective in cuprate as well as iron-based superconductors due to their intrinsically layered crystallographic structure. However Fe(Se,Te) thin films grown on CaF2 substrate result less anisotropic with respect to all the other iron based superconductors. We present the first study on the angular dependence of the flux flow instability, which occurs in the flux flow regime as a current driven transition to the normal state at the instability point (I*, V*) in the current-voltage characteristics. The voltage jumps are systematically investigated as a function of the temperature, the external magnetic field, and the angle between the field and the Fe(Se,Te) film. The scaling procedure based on the anisotropic Ginzburg-Landau approach is successfully applied to the observed angular dependence of the critical voltage V*. Anyway, we find out that Fe(Se,Te) represents the case study of a layered material characterized by a weak anisotropy of its static superconducting properties, but with an increased anisotropy in its vortex dynamics due to the predominant perpendicular component of the external applied magnetic field. Indeed, I* shows less sensitivity to angle variations, thus being promising for high field applications.
“…In the case of sample W20 the characteristic transition associated to FFI is observed. In this case, the presence of a smoothed jump is the result of the coexistence of thermal and electronic mechanisms [11], [12].…”
Section: A Current-voltage Characteristics and Flux Flow Instabilitymentioning
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
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
