Fermi surface and superconductivity in noncentrosymmetricCeRhSi3

We report measurements of the ac magnetic susceptibility and de Haas\char21{}van Alphen effect (dHvA) in $\mathrm{Ce}\mathrm{Rh}{\mathrm{Si}}_{3}$ up to a pressure $P=29.5\phantom{\rule{0.3em}{0ex}}\mathrm{kbar}$ with the field in the $c$ direction. The observed Fermi surface suggests that $\mathrm{Ce}\phantom{\rule{0.2em}{0ex}}4f$ electrons are itinerant even when antiferromagnetic order occurs. Effective masses decrease with $P$: no enhancement is observed as the antiferromagnetic transition temperature is reduced by the application of pressure. Analyses of dHvA oscillations in the mixed state indicate that the influence of the superconducting energy gap is negligible for some orbits.