BIAS VOLTAGE-DEPENDENCE OF MAGNETOQUANTUM OSCILLATION AMPLITUDE OF RESISTIVITY IN METAL POINT CONTACTS

Al and Be point contacts are measured to study magnetoquantum oscillat ions in resistance as a function of potential difference applied acros s the contact. For one group of the contacts the amplitude of resistan ce oscillations in magnetic field increases with voltage and is simila r to the point-contact spectrum of electron-phonon interaction. For ot her point contacts the magnetoresistance shows a decrease in the oscil lation amplitude with increasing bias across the contact. Both the inc rease and the decrease in the oscillation amplitude depend nonmonotono nsly on energy. It has been suggested that the above effects are due t o electron scattering by nonequilibrium phonons or Fermi-liquid effect s in nonequilibrium electron systems.