Electron–phonon interaction in gold and silver microcontacts
Аннотация
Microcontact spectroscopy (MS) has been used to make a detailed investigation of the Au and Ag spectra, and the MC electron-phonon interaction (EPI) function G(eV)=α˜2(eV)F(eV) has been determined where α˜2(eV) is the mean square matrix element of the EPI and F(eV) is the phonon density of states. The MC spectra of Ag show peaks in the region of the transverse (TA) phonons at 10.6±0.1 mV, 12.8±0.1 mV and for longitudinal (LA) phonons at 20.1±0.2 mV;Au shows these respectively at 9.9±0.1 mV (TA) and 17.8±0.1 mV (LA). It has been found that the initial region in the MC spectrum obeys an (eV)2.5 law for small energies 0<eV≲1/4ħωmax(ωmax is the maximum phonon frequency and V is the voltage at the contact); with eV > ħωmax maxima are observed which correspond to two-phonon processes (TA + LA). A comparison of the MC spectra of Au and Ag with F(eV) shows that α˜2(eV) is not a monotonically decreasing function with increasing energy, but has minima and maxima. The parameter λ for the EPI has also been calculated for these metals.