Magnetoquantum oscillations in the resistance of metallic point   contacts: Influence of nonequilibrium phonons
  The amplitude of magnetoresistance quantum oscillations of Al and Be point contacts in a magnetic field parallel to the contact axis has been studied as a function of voltage applied over the contact. It was found that for one group of contacts the oscillation amplitude nonmonotonously increases with the bias voltage increase, while for the other part of the contacts a decrease of amplitude was observed. The scattering of electrons with nonequilibrium phonons and also phonon-phonon collisions will be discussed as the possible reasons of the observed effects. 
N.L. Bobrov, J.A. Kokkedee, N.N. Gribov, I.K. Yanson, A.G.M. Jansen,   P. Wyder
cond-mat.mes-hall