  Anomalous high-harmonic generation (HHG) arises in certain solids when
irradiated by an intense laser field, as the result of a nonlinear
perpendicular current akin to a Hall current. Here, we theoretically
characterize the anomalous HHG mechanism, via development of an ab-initio
methodology for strong-field laser-solid interaction that allows a rigorous
decomposition of the total current. We identify two key characteristics of the
anomalous harmonic yields: an overall increase with laser wavelength; and
pronounced minima at certain intensities or wavelengths around which the
emission time profiles drastically change. Such signatures can be exploited to
disentangle the anomalous harmonics from the competing interband harmonics, and
thus pave way for the experimental identification and time-domain control of
pure anomalous harmonics.
