Abstract
The quantum Hall effect (QHE) is traditionally considered to be a purely two-dimensional (2D) phenomenon. Recently, however, a three-dimensional (3D) version of the QHE was reported in the Dirac semimetal ZrTe5. It was proposed to arise from a magnetic-field-driven Fermi surface instability, transforming the original 3D electron system into a stack of 2D sheets. Here, we report thermodynamic, spectroscopic, thermoelectric and charge transport measurements on such ZrTe5 samples. The measured properties: magnetization, ultrasound propagation, scanning tunneling spectroscopy, and Raman spectroscopy, show no signatures of a Fermi surface instability, consistent with in-field single crystal X-ray diffraction. Instead, a direct comparison of the experimental data with linear response calculations based on an effective 3D Dirac Hamiltonian suggests that the quasi-quantization of the observed Hall response emerges from the interplay of the intrinsic properties of the ZrTe5 electronic structure and its Dirac-type semi-metallic character.
Highlights
The quantum Hall effect (QHE) is traditionally considered to be a purely two-dimensional (2D) phenomenon
We find that the magnetization does not show any signatures of the formation of a charge-density wave (CDW)
Our model provides a way to derive and understand the Hall conductivity of a genuine 3D electron systems from the conductance quantum scaled by a characteristic length when only the lowest few Landau bands are occupied
Summary
The quantum Hall effect (QHE) is traditionally considered to be a purely two-dimensional (2D) phenomenon. By increasing B, the LLs shift through the Fermi level EF one after the other, leading to quantum oscillations in transport and thermodynamic quantities[1]. At sufficiently large magnetic field, where only a few LLs are occupied, 2D electron systems (2DESs) enter the quantum Hall regime[2,3,4,5]. This regime is characterized by a fully gapped electronic spectrum in the bulk and current-carrying gapless edge states, leading to quantization of the Hall conductance Gxy = νe2/h, where ν is the Landau-level filling factor, e is the elementary charge, and h is Planck’s constant. Current flow is allowed in the direction parallel to B
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