Cyclotron-Resonance Harmonics in the ac Response of a 2D Electron Gas with Smooth Disorder

The frequency-dependent conductivity ${\sigma }_{xx}(\omega )$ of 2D electrons subjected to a transverse magnetic field and smooth disorder is calculated. The interplay of Landau quantization and disorder scattering gives rise to an oscillatory structure that survives in the high-temperature limit. The relation to recent experiments on photoconductivity by Zudov et al. and Mani et al. is discussed.

Figure 1

(a) SCBA equation for the Green function; (b) the dynamical conductivity with vertex correction (c).

Figure 2

Magneto-oscillations of the dynamical conductivity for a system with smooth disorder, ${\tau }_{\mathrm{t}\mathrm{r}\mathrm{,}\mathrm{0}}/{\tau }_{\mathrm{s}\mathrm{,}\mathrm{0}}=10$. Solid line: separated LLs, ${\omega }_c{\tau }_{\mathrm{s}\mathrm{,}\mathrm{0}}/\pi =3.25$; dashed line: overlapping LLs, ${\omega }_c{\tau }_{\mathrm{s}\mathrm{,}\mathrm{0}}/\pi =1$. Inset: ${\sigma }_{xx}$ for fixed $\omega {\tau }_{\mathrm{s}\mathrm{,}\mathrm{0}}/2\pi =1$ as a function of ${\omega }_c$.