Cyclotron resonance
= Cyclotron resonance
<Cyclotron resonance> is resonant absorption by charged particles in a <magnetic field> when an applied oscillating electric field drives their cyclotron motion. For a parabolic band, the resonance frequency is $\omega_c=|q|B/m^*$, so measuring it determines the <cyclotron effective mass>. In the quantum description, transverse <electric dipole transitions> connect adjacent <Landau levels>, whose separation is $\hbar\omega_c$. For an electron and a field along $z$, only the circular polarization rotating in the electron's orbital sense drives the positive-frequency resonance. Scattering broadens the absorption peak; resolving it requires an orbital period short compared with the relaxation time.