Eur. Phys. J. B (2012) 85: 57
https://doi.org/10.1140/epjb/e2011-20821-6

Regular Article

Detailed study of the de Haas-van Alphen effect in the Shubnikov state of LuNi₂B₂C

¹ Hochfeld-Magnetlabor Dresden (HLD), Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden, Germany
² Leibniz-Institute for Solid State and Materials Research (IFW-Dresden), 01171 Dresden, Germany
³ Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, 50011 Iowa, USA

^a Present address: Dresden University of Technology, Institute for Materials Science, Helmholtzstraße 7, 01069 Dresden, Germany. e-mail: Beate.Bergk@tu-dresden.de

Received: 7 October 2011
Received in final form: 12 December 2011
Published online: 13 February 2012

Abstract

We present de Haas-van Alphen (dHvA) measurements in the normal and in the superconducting state of LuNi₂B₂C. Inside the superconducting state, we observe quantum oscillations of a spherical Fermi-surface sheet in all crystallographic directions. Apart from the field region close to the phase transition where a strong peak effect hampers the analysis of the dHvA signal, the additional damping of the quantum oscillations inside the superconducting state is much smaller than expected from theory. For the magnetic field aligned along the [100] direction, three different dHvA frequencies are visible in the superconducting state. In particular, the orbit related to a cushion-like Fermi surface does not show any additional damping at and below the upper critical field contrary to theoretical expectations of simple effective one-band theories. Consequently, the superconducting gap on this Fermi-surface sheet can only evolve at lower fields than the observed bulk critical field, B_c2 ≈ 8 T, which clearly points to a Fermi-surface-sheet-dependent gap opening in LuNi₂B₂C.