DE HAAS-VAN-ALPHEN EFFECT IN CANONICAL AND GRAND-CANONICAL MULTIBAND FERMI-LIQUID

A qualitatively different character of de Haas-van Alphen oscillations has been found in a multiband (quasi)two-dimensional Fermi liquid wit h a fixed fermion density n(e) (canonical ensemble) compared with an o pen system where the chemical potential mu is kept fixed (grand canoni cal ensemble). A new fundamental period P-f appears when n(e) is fixed , a damping of the Landau levels is relatively small and a background density of states is negligible. P-f is determined by the total densit y rather than by the partial densities of carriers in different bands: P-f = 1/2n(e) phi for spin-split Landau levels and P-f = 1/n(e) phi i n the case of spin degenerate levels where phi is the flux quantum.