We present a study of the frequency dependence of the vortex dynamics in a conventional superconductor. We have employed a swept frequency, Corbino disk technique to investigate the temperature (3.6 K - T(c)) and high-field (from H(c2)/2 to H(c2)) microwave complex resistivity in Nb thin (20-40 nm) films as a function of the frequency (1-20 GHz). We have found several previously unnoticed features: (i) a field-dependent depinning frequency in the GHz range; (ii) deviations from the accepted frequency dependence [1], that can be ascribed to some kind of vortex creep; and (iii) the presence of switching phenomena, reminiscent of vortex instabilities. We discuss the possible origin of the features here reported. (C) 2010 Elsevier B.V. All rights reserved.
Pompeo, N., Silva, E., Sarti, S., Attanasio, C., Cirillo, C. (2010). New aspects of microwave properties of Nb in the mixed state. PHYSICA. C, SUPERCONDUCTIVITY, 470(19), 901-903 [10.1016/j.physc.2010.02.063].
New aspects of microwave properties of Nb in the mixed state
POMPEO, NICOLA;SILVA, Enrico;
2010-01-01
Abstract
We present a study of the frequency dependence of the vortex dynamics in a conventional superconductor. We have employed a swept frequency, Corbino disk technique to investigate the temperature (3.6 K - T(c)) and high-field (from H(c2)/2 to H(c2)) microwave complex resistivity in Nb thin (20-40 nm) films as a function of the frequency (1-20 GHz). We have found several previously unnoticed features: (i) a field-dependent depinning frequency in the GHz range; (ii) deviations from the accepted frequency dependence [1], that can be ascribed to some kind of vortex creep; and (iii) the presence of switching phenomena, reminiscent of vortex instabilities. We discuss the possible origin of the features here reported. (C) 2010 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
