Point-contact electron–phonon interaction function in tantalum
Abstract
Tantalum is studied by the method of point-contact (PC) spectroscopy: the parameter λpc and the absolute intensity of the PC EPI function are determined, and the form of the EPI function is determined more accurately. Both homocontacts Ta–Ta and heterocontacts Ta–Cu and Ta-Au were studied. It was found that the contributions of copper and gold to the spectrum of the heterocontact are not noticeable, though the forms of the PC spectra of Ta in homo- and heterocontacts are different. The intensities of the spectra of Ta–Ta homocontacts and Ta–Cu heterocontacts turned out to be close to one another. Simple expressions, enabling numerical calculations of the PC characteristics for geometrically symmetric heterocontacts in the approximation of a spherical Fermi surface, are derived, based on the theory. It is shown that the use of the free-electron approximation in the numerical estimates leads to an error. It is proposed that the effective mass approximation be used for such estimates.