Two-dimensional semimetal in a wide HgTe quantum well: magnetotransport and energy spectrum

TL;DR

This study experimentally investigates the magnetotransport properties of a 20.2 nm HgTe quantum well, revealing significant deviations from theoretical models in the energy spectrum and effective mass of charge carriers.

Contribution

It provides new experimental insights into the energy spectrum and effective mass in HgTe quantum wells, challenging existing theoretical predictions.

Findings

Hole effective mass is approximately 0.2 m_0 and nearly independent of quasimomentum.

Experimental data shows the hole energy spectrum is electron-like near k=0.

The measured effective mass near k=0 is about -0.005 m_0, differing from theoretical estimates.

Abstract

The results of experimental study of the magnetoresistivity, the Hall and Shubnikov-de Haas effects for the heterostructure with HgTe quantum well of 20.2 nm width are reported. The measurements were performed on the gated samples over the wide range of electron and hole densities including vicinity of a charge neutrality point. Analyzing the data we conclude that the energy spectrum is drastically different from that calculated in framework of $kP$-model. So, the hole effective mass is equal to approximately $0.2 m_0$ and practically independent of the quasimomentum ($k$) up to $k^2\gtrsim 0.7\times 10^{12}$ cm$^{-2}$, while the theory predicts negative (electron-like) effective mass up to $k^2=6\times 10^{12}$ cm$^{-2}$. The experimental effective mass near k=0, where the hole energy spectrum is electron-like, is close to $-0.005 m_0$, whereas the theoretical value is about $-0.1 m_0$.