2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/142768We develop a systematic theory of microwave-induced oscillations in magnetoresistivity of a 2D electron gas in the vicinity of fractional harmonics of the cyclotron resonance, observed in recent experiments. We show that in the limit of well-separated Landau levels the effect is dominated by a change of the distribution function induced by multiphoton processes. At moderate magnetic field, a single-photon mechanism originating from the microwave-induced sidebands in the density of states of disorder-broadened Landau levels becomes important.4 pages, 2 figures; V2: published version (typos corrected, references added and updated)Mesoscale and Nanoscale PhysicsDisordered Systems and Neural Networkstext