Eur. Phys. J. B 49, 421-424 (2006)
https://doi.org/10.1140/epjb/e2006-00094-0

The effect of topological fluctuations on the heat capacity of superconductor

¹ Max-Plank Institute for Physics of Complex Systems, Dresden, 01187 Germany and Landau Institute for Theoretical Physics, RAS, Chernogolovka, Moscow District, 142432, Russia
² Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne Il 60439 and Coherentia-INFM, CNR, Viale del Politecnico 1, 00133 Rome, Italy

Corresponding author: ^a varlamov@ing.uniroma2.it

Received: 6 December 2005
Published online: 31 March 2006

Abstract

The effect of topological excitations in the form of small size (r ≪ξ(T)) vortex rings on thermodynamics of a bulk superconductor is considered. These specific short wavelength fluctuations of the order parameter are analogous to small vortex-antivortex pairs in superconducting film which were recently studied in Y.N. Ovchinnikov, A.A. Varlamov, Phys. Rev. Lett. 94, 107007 (2004). The corresponding contribution to the free energy below T_c is calculated. It is shown that fluctuations of this type give the main temperature dependent contribution to the heat capacity of the superconductor in the sufficiently large interval of temperatures below the transition point. Important, that the sign of this contribution is opposite to that one appearing due to the usual long wavelength fluctuation, leading to smearing of the BCS jump of heat capacity.