Magneto-optics of massless Kane fermions: Role of the flat band and unusual Berry phase

TL;DR

This paper investigates the unique magneto-optical properties of HgCdTe with massless Kane fermions, emphasizing the influence of a flat band and an unusual Berry phase, supported by numerical calculations aligning with experiments.

Contribution

It provides a detailed numerical analysis of magneto-optical responses in a pseudospin-1 Kane fermion system, highlighting the role of the flat band and non-{ extpi}-quantized Berry phase.

Findings

Good agreement between calculations and experimental data.

Identification of flat band signatures in magneto-optical spectra.

Evidence of a non-{ extpi}-quantized Berry phase in the system.

Abstract

HgCdTe at a critical cadmium doping has a bulk dispersion which includes two linear cones meeting at a single point at zero energy, intersecting a nearly flat band, similar to the pseudospin-1 Dirac-Weyl system. In the presence of a finite magnetic field, these bands condense into highly degenerate Landau levels. We have numerically calculated the frequency-dependent magneto-optical and zero-field conductivity of this material using the Kane model. The calculations show good agreement with recent experimental measurements. We discuss the signature of the flat band and the split peaks of the magneto-optics in terms of general pseudospin-s models and propose that the system exhibits a non-{\pi}-quantized Berry phase, found in recent theoretical work.