Analytical approach to the thermal instability of superconducting films under high current densities

Abstract

Using the Green's function of the 3D heat equation, we develop an analytical account of the thermal behaviour of superconducting films subjected to electrical currents larger than their critical current in the absence of an applied magnetic field. Our model assumes homogeneity of films and current density, and besides thermal coefficients employs parameters obtained by fitting to experimental electrical field -current density characteristics at constant bath temperature. We derive both a tractable dynamic equation for the real temperature of the film up to the supercritical current density J * (the lowest current density inducing transition to the normal state), and a thermal stability criterion that allows prediction of J * . For two typical YBCO films, J * predictions agree with observations to within 5%. These findings strongly support the hypothesis that a currentinduced thermal instability is generally the origin of the breakdown of superconductivity under high electrical current densities, at least at temperatures not too far from Tc.

Competition between intrinsic and extrinsic effects in the quenching of the superconducting state in Fe(Se,Te) thin films

“…The occurrence of this thermal instability in HTSCs at zero applied magnetic field has been theoretically described as a pure consequence of a temperature runaway which takes place up to the quenching temperature T * , where a very steep voltage jump sets in. 12,27 It is claimed that, under certain experimental conditions, heating effects become predominant, 12 and at sufficiently high current densities, cuprate HTSCs become thermally unstable. 27 On the other hand, the LO model has been extended by Bezuglyj and Shklovskij 11 (BS) in order to include the effect of self-heating near T c in a finite magnetic field.…”

New Measurements of the Transition to the Normal State Induced by High Current Densities in High-Tc Superconductor Microbridges under Thermal Smallness Conditions

“…In fact, as the temperature dependence of the dissipation per unit volume, W, is a crucial ingredient for a thermal runaway [6,10,13,14], the behavior of J*(H)/Jc(H) could be associated,…”

Demonstration experiments for solid-state physics using a table-top mechanical Stirling refrigerator

“…The levitation observed when approaching superconducting samples and magnets has been extensively studied [15,16,17]. The ¶ See, for instance, references [10,11].…”

“…Both pistons (2) reciprocate inside the cylinders (1), so the gas is forced through two channels (10) which feed an expander-regenerator assembly (( 8) and ( 9)). Its driving plunger (11) is tied to a spring compensation system (12), allowing negligible spurious vibrations. Two magnetic motors (3) produce the reciprocation of the pistons.…”