Two-Dimensional Quantum Hall Effect and Zero Energy State in Few-Layer ZrTe₅

Area of Science:

• Condensed matter physics
• Materials science
• Topological materials

Background:

• Topological matter is crucial in condensed matter physics.
• Zirconium pentatelluride (ZrTe5) is a Dirac semimetal near the topological insulator boundary.
• Previous studies faced challenges with ZrTe5 thin film degradation, preventing high-quality device fabrication and observation of the quantum Hall effect (QHE).

Purpose of the Study:

• To fabricate high-quality few-layer ZrTe5 devices.
• To overcome sample degradation issues in ZrTe5.
• To investigate the potential for quantum spin Hall effect and observe QHE.

Main Methods:

• Advanced sample preservation techniques for thin films.
• Magneto-transport measurements.
• Characterization of carrier mobility and electronic states.

Main Results:

• Achieved high carrier mobility (∼3500 cm2 V−1 s−1) in preserved ZrTe5 thin films.
• Successfully observed the integer quantum Hall effect (QHE) in few-layer ZrTe5.
• Identified a zero-energy state linked to the bulk band gap, providing evidence for gapless topological states.

Conclusions:

• The study demonstrates a method to preserve intrinsic properties of ZrTe5 thin films.
• The observation of QHE in ZrTe5 confirms its potential as a high-quality 2D topological material.
• The findings provide strong evidence for the existence of gapless topological states within the band gap of ZrTe5.