Flicker noise and electron–phonon interaction in metallic point contacts

Flicker noise in metallic point contacts, due to the scattering of electrons by two-level systems (TLS), was studied. In the diffusion regime le−im ≪ d the intensity of the noise obeys the 1/Ne law, while in the ballistic limit le−im ≫ d it obeys the 1/Ne1/3 law (Ne is the number of charge carriers in the region with a volume of V0 ∼ d3, le−im is the electron-impurity scattering length). When electron–phonon scattering is taken into account the bias-voltage dependence of the spectral intensity of the noise has certain features (of the smoothed step type) with a relative intensity of the order of d/le−ph for biases equal to the characteristic phonon energies. These features are most distinct when the number of TLS in the contact is small, when the important TLS are those which lie at distances from the contact of the order of or greater than the electron–phonon relaxation length le−ph.

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