High frequency relaxation kinetics in metal and high-Tc superconductor nanocontacts

Abstract

The presented work deals with an interesting and relatively simple experimental method, called Point Contact Spectroscopy that permits to study the behaviour of quasiparticles (phonons) in conductive solids: their generation, interactions with electrons, disappearance. We could investigate by this technique also more exotic processes for other quasiparticles (conduction electrons), such as their trapping in a semi metal crystal lattice (Sb), the pairing in superconducting solids, and the absorption of phonons by electrons. Point Contact Spectroscopy consists in the creation of a nanocontact (10-100 nm in diameter) between two conductors and in monitoring its response to electromagnetic fields. When kept in liquid helium, an enormous current density in the range of 109 A/cm2 can be created in such a constriction and in these conditions, the contact becomes an instrument for revealing the quantum properties of electrons and phonons.