2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/155988Electron-electron interactions give rise to the correction, δσ^{int}(ω), to the ac magnetoconductivity, σ(ω), of a clean 2D electron gas that is periodic in ω_c^{-1}, where ω_c is the cyclotron frequency. Unlike conventional harmonics of the cyclotron resonance, which are periodic with ω, this correction is periodic with ω^{3/2}. Oscillations in δσ^{int}(ω) develop at low magnetic fields, ω_c\llω, when the conventional harmonics are suppressed by the disorder. Their origin is a {\em double} backscattering of an electron from the impurity-induced Friedel oscillations. During the time \simω^{-1} between the two backscattering events the electron travels only a {\em small portion} of the Larmour circle.4+ pages, 3 figuresMesoscale and Nanoscale Physicstext