The electrical transport in superconductors at nonzero frequencies is affected by the normal and superfiuid fractions, as well as moving vortices, resulting in intricate expressions for the complex resistivity. In MgB2 , additional complications arise from the two-band nature of this material. We present an accurate study of microwave resistivity data measured in MgB2 thin films by means of the Corbino disk broadband technique between 2 and 20 GHz. We show that a two-fluid model applies well in a relatively large region of the H–T phase diagram. Excellent agreement is found between the derived superfluid parameters (superfluid density, upper critical field) and theoretical predictions. In the same H–T region we isolate and discuss the vortex motion complex resistivity. To this end, we make use of the expressions given by the model by Coffey and Clem (CC). We show that the frequency dependence of the complex vortex resistivity recovers the CC model. However, the temperature and field dependence of the obtained parameters are at odds with the assumptions of the model. We discuss possible explanations of these oddities by considering collective pinning of vortices.

S., S., C., A., R., F., M., G., Pompeo, N., E., S. (2007). Vortex motion and quasiparticle resistivity in MgB2 at microwave frequencies. JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, 20, 51-57 [10.1007/s10948-006-0191-6].

Vortex motion and quasiparticle resistivity in MgB2 at microwave frequencies

POMPEO, NICOLA;
2007-01-01

Abstract

The electrical transport in superconductors at nonzero frequencies is affected by the normal and superfiuid fractions, as well as moving vortices, resulting in intricate expressions for the complex resistivity. In MgB2 , additional complications arise from the two-band nature of this material. We present an accurate study of microwave resistivity data measured in MgB2 thin films by means of the Corbino disk broadband technique between 2 and 20 GHz. We show that a two-fluid model applies well in a relatively large region of the H–T phase diagram. Excellent agreement is found between the derived superfluid parameters (superfluid density, upper critical field) and theoretical predictions. In the same H–T region we isolate and discuss the vortex motion complex resistivity. To this end, we make use of the expressions given by the model by Coffey and Clem (CC). We show that the frequency dependence of the complex vortex resistivity recovers the CC model. However, the temperature and field dependence of the obtained parameters are at odds with the assumptions of the model. We discuss possible explanations of these oddities by considering collective pinning of vortices.
2007
S., S., C., A., R., F., M., G., Pompeo, N., E., S. (2007). Vortex motion and quasiparticle resistivity in MgB2 at microwave frequencies. JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, 20, 51-57 [10.1007/s10948-006-0191-6].
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11590/146778
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 4
  • ???jsp.display-item.citation.isi??? 4
social impact