Precursor diamagnetism above the superconducting transition in YNi<InlineEquation ID="Equ1"> <EquationSource Format="TEX">$_\mathsf{2}$</EquationSource> </InlineEquation>B<InlineEquation ID="Equ2"> <EquationSource Format="TEX">$_\mathsf{2}$</EquationSource> </InlineEquation>C

High-resolution SQUID magnetization measurements in a single crystal of YNi<Subscript>2</Subscript>B<Subscript>2</Subscript>C around the superconducting transition are reported. The diamagnetic magnetization -M <Subscript> fl </Subscript> at constant field H as a function of temperature and isothermal magnetization curves -M <Subscript> fl </Subscript> vs. H are used to derive insights on precursor phenomena approaching the bulk transition temperature <InlineEquation ID="Equ3"> <EquationSource Format="TEX">$T_c(H=0)=15.25\pm0.02$</EquationSource> </InlineEquation> K. The precursor diamagnetism is found strongly enhanced with respect to the conventional Ginzburg-Landau value for Gaussian fluctuations and the curves -M <Subscript> fl </Subscript> vs. H exhibit an upturn with the field and hysteretic effects up to T <Superscript>*</Superscript>=15.4 K. These results are interpreted in terms of a non-zero order parameter in superconducting droplets above the bulk T <Subscript> c </Subscript>. These droplets are likely to be related to inhomogeneities resulting from small amount of boron to carbon substitutions. Copyright Springer-Verlag Berlin/Heidelberg 2003