Processes of the second order with respect to the electron–phonon interaction in point contacts of normal metals

The authors have derived, to within terms of the second order in d/lε∞ [d is the contact diameter, lε∞=vF/λωD is the inelastic electron mean free path, and λ is the electron-phonon interaction (EPI) constant], an expression for the second derivative of the I–V characteristic, gpc(1)(eV)+ const1∫​0eVgpc(2)(ω)(dω)/(ω)+ const2∫​0eVfpc(ω,eV−ω)dω, where gpc(1)(ω)≡gpc(ω)=α^2(ω)F(ω) is the first-order EPI function of the contact, and gpc(2)(ω) and fpc(ω1,ω2) are second-order EPI functions of the contact. The second term represents an energy-dependent “background” that appears in point-contact spectra because of reabsorption and drag of nonequilibrium phonons, and the third term describes two-phonon processes. The function gpc(2)(ω) is distinguished from gpc(1)(ω) by (in addition to the K factor) the presence of the phonon group velocity wz=δω˙q/δqz in the denominator of the integrand and, therefore, is a more singular function of ω than is qpc(1)(ω), and contains additional information about the electron–phonon interaction of the metal.

Перевод пока недоступен