Europhys. Lett.
Volume 72, Number 4, November 2005
Page(s) 638 - 644
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 12 October 2005
Europhys. Lett., 72 (4), pp. 638-644 (2005)
DOI: 10.1209/epl/i2005-10269-9

Microwave response of $\chem{V_3 Si}$ single crystals: Evidence for two-gap superconductivity

Yu. A. Nefyodov, A. M. Shuvaev and M. R. Trunin

Institute of Solid State Physics - 142432 Chernogolovka, Moscow district, Russia

received 13 September 2005; accepted 16 September 2005
published online 12 October 2005

The investigation of the temperature dependences of microwave surface impedance and complex conductivity of V3Si single crystals with different stoichiometry allowed to observe a number of peculiarities which are in remarkable contradiction with single-gap Bardeen-Cooper-Schrieffer theory. At the same time, they can be well described by the two-band model of superconductivity, thus strongly evidencing the existence of two distinct energy gaps with zero-temperature values $\Delta_1\approx 1.8\,T_c$ and $\Delta_2\approx 0.95\,T_c$ in $\chem{V_3 Si}$.

74.25.Nf - Response to electromagnetic fields (nuclear magnetic resonance, surface impedance, etc.).
74.70.Ad - Metals; alloys and binary compounds (including A15, $\chem{Mg B_2}$, etc.).

© EDP Sciences 2005