Characterizing Anomalous High-Harmonic Generation in Solids

High-harmonic generation (HHG) in condensed-phase systems has gained intense interest in the last decade, for its dual promise as a compact source of ultrafast extreme ultraviolet laser pulses, and as a spectroscopic, sub-femtosecond-resolution tool of driven electron dynamics. In this work we characterize the nonlinear anomalous current that arises when a material with Berry curvature is exposed to an intense, infrared laser pulse, through ab-initio calculations of HHG in MoS2. We resolve the nonlinear current that gives rise to high-order harmonics into its four different components and discuss their relative importance. We identify two unique properties of the anomalous harmonic yield that could be exploited to disentangle the anomalous harmonics from competing HHG mechanisms: an overall yield increase with laser wavelength; and pronounced minima at certain laser wavelengths and laser intensities. Finally, we show how the Berry curvature can be reconstructed from the angular and spectral variation of the harmonic yield.