Many-particle hybridization of optical transitions from zero-mode Landau levels in HgTe quantum wells

TL;DR

This study uses far-infrared magnetospectroscopy to investigate zero-mode Landau levels in HgTe quantum wells, revealing many-particle interactions as the key factor in their behavior, beyond single-particle models.

Contribution

It demonstrates that electron-electron interactions, not just inversion asymmetries, explain the anticrossing of zero-mode Landau levels in HgTe quantum wells.

Findings

Optical transitions from zero-mode Landau levels are influenced by many-particle interactions.

Single-particle models are insufficient to explain the observed anticrossing behavior.

The hybridization mechanism is intrinsic to HgTe quantum wells regardless of crystallographic orientation.

Abstract

We present far-infrared magnetospectroscopy measurements of a HgTe quantum well in the inverted band structure regime over the temperature range of 2 to 60 K. The particularly low electron concentration enables us to probe the temperature evolution of all four possible optical transitions originating from zero-mode Landau levels, which are split off from the edges of the electron-like and hole-like bands. By analyzing their resonance energies, we reveal an unambiguous breakdown of the single-particle picture indicating that the explanation of the anticrossing of zero-mode Landau levels in terms of bulk and interface inversion asymmetries is insufficient. Instead, the observed behavior of the optical transitions is well explained by their hybridization driven by electron-electron interaction. We emphasize that our proposed many-particle mechanism is intrinsic to HgTe quantum wells of any crystallographic orientation, including (110) and (111) wells, where bulk and interface inversion asymmetries do not induce the anticrossing of zero-mode Landau levels.