Semiclassical theory of magnetic quantum oscillations in a two-dimensional multiband canonical Fermi liquid

The semiclassical Lifshitz-Kosevich description of quantum oscillations is extended to a multiband two-dimensional Fermi liquid with a constant number of electrons. The amplitudes of oscillations with combination frequencies, recently predicted and observed experimentally, are analytically derived and compared with the single-band amplitudes. The combination amplitudes de:cay with temperature exponentially faster than the standard harmonics, and this provides st valuable tool for their experimental identification.