Eur. Phys. J. B 35, 325-329 (2003)
https://doi.org/10.1140/epjb/e2003-00284-2

Precursor diamagnetism above the superconducting transition in YNi₂B₂C

¹ Department of Physics “A. Volta” and Unita' INFM, University of Pavia,Via Bassi 6, 27100 Pavia, Italy
² Laboratorium voor Vaste-Stoffisyca en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium
³ Department of Theoretical Physics, Faculty of Physics, Sofia University St. Kliment Ohridski, 5 J. Bourchierb Blvd., 1164 Sofia Bulgaria
⁴ Institut fur Festkorper and Werkstofforschung Dresden, 01171, Postfach 270116, Germany

Corresponding author: ^a lascialfari@fisicavolta.unipv.it

Received: 13 December 2002
Revised: 23 April 2003
Published online: 15 October 2003

Abstract

High-resolution  SQUID  magnetization  measurements  in a single crystal of YNi₂B₂C  around the superconducting transition are reported. The diamagnetic magnetization -M_fl at constant field H as a function of temperature and isothermal magnetization curves -M_fl vs. H are used to derive insights on precursor phenomena approaching the bulk transition temperature  K. The precursor diamagnetism is found strongly enhanced with respect to the conventional Ginzburg-Landau value for Gaussian fluctuations and the curves -M_fl vs. H exhibit an upturn with the field and hysteretic effects up to  K. These results are interpreted in terms of a non-zero order parameter in superconducting droplets above the bulk T_c. These droplets are likely to be related to inhomogeneities resulting from small amount of boron to carbon substitutions.