Interrelation of resistivity and inelastic electron-phonon scattering rate in impure NbC films

Abstract

A complex study of the electron-phonon interaction in thin NbC films with electron mean free path lϭ2 -13 nm gives strong evidence that electron scattering is significantly modified due to the interference between electron-phonon and elastic electron scattering from impurities. The interference T 2 term, which is proportional to the residual resistivity, dominates over the Bloch-Grüneisen contribution to resistivity at low temperatures up to 60 K. The electron energy relaxation rate is directly measured via the relaxation of hot electrons heated by modulated electromagnetic radiation. In the temperature range 1.5-10 K the relaxation rate shows a weak dependence on the electron mean free path and strong temperature dependence ϳT n , with the exponent nϭ2.5-3. This behavior is explained well by the theory of the electron-phonon-impurity interference taking into account the electron coupling with transverse phonons determined from the resistivity data.

Relaxation of the resistive superconducting state in boron-doped diamond films

“…Application of a perpendicular magnetic field brings the film into a resistive state at various temperatures, which makes it possible to measure the energyrelaxation rate as a function of temperature, although over a limited range of temperatures. The technique has been applied to various materials, usually providing different temperature dependences of the relaxation rate, for example T 2 in Nb film [13], T 1.6 in NbN [14], and T 3 in TiN [15] and in NbC [16].…”

“…The coefficient 9.1 results from averaging over all electron states contributing to τ e−ph [16]. This theoretical model assumes that all the impurity scatterers for electrons vibrate in phase with the host atoms.…”

Large effects due to electron–phonon-impurity interference in the resistivity of Pt/C-Ga composite nanowires

“…Our analysis shows that the interference mechanism remains the dominant contribution to the resistivity of these wires, to significantly higher temperatures than has been noted in other material systems. [3][4][5][6][7][8][9] This observation is attributed to strong electronic disorder in these nanowires, combined with their high Debye temperature. We furthermore show the resistivity to be robust to thermal cycling, and insensitive to large magnetic fields, which may suggest the application of these structures as nanoscale thermometers.…”

“…1 In previous work, evidence for the interference term has been observed in studies of the resistivity of thin metal films, fabricated using a variety of methods. [3][4][5][6][7][8][9] In this letter, we discuss the contribution of the interference mechanism to the resistivity of highly resistive ͑40-400 ⍀ cm at 4.2 K͒ Pt/C composite nanowires fabricated by focused-ion-beam ͑FIB͒ deposition. Our analysis shows that the interference mechanism remains the dominant contribution to the resistivity of these wires, to significantly higher temperatures than has been noted in other material systems.…”

Engineering Physics of Superconducting Hot-Electron Bolometer Mixers

“…In some laboratories (Burke et al, 1996;Ekstrom et al, 1995;Siddiqi et al, 2002;Skalare et al, 1995;Wilms Floet et al, 1999) elemental superconductors such as niobium and aluminium have been used with interesting results for the physical processes. (In addition some work has been done on NbC (Il'in et al, 1998;Karasik et al, 1996). These competing scenarios have, for about a decade, led to a classification of superconducting hot-electron bolometer mixers into lattice-cooled (or phonon-cooled ) on the one hand and diffusion-cooled on the other hand.…”