De Haas-van Alphen study in the superconducting state of YNi2B2C.

Abstract

In the borocarbide superconductor YNi{sub 2}B{sub 2}C the de Haas{endash}van Alphen (dHvA) oscillations have been observed continuously at the upper critical field {ital B}{sub {ital c}2} for the transition from the normal into the superconducting state. In the normal state above {ital B}{sub {ital c}2}=10.5T six different frequencies were found in magnetic fields up to 23T and for {Theta}=14.4{degree}. The smallest orbit with {ital F}{sub {alpha}}=511T is present down to about 4T, but with an additional attenuation of the dHvA signal in the superconducting state relative to an extrapolation of the standard Lifshitz-Kosevich formula. The observation of magnetoquantum oscillations over such a wide field range and very close to {ital B}{sub {ital c}2} enables a detailed discussion of the damping in the context of recent theories of these oscillations in the superconducting state. {copyright} {ital 1996 The American Physical Society.}