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Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser

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Controlling and visualizing Dirac physics in topological semimetal heterostructures.

David A Kealhofer¹, Robert Kealhofer¹, Daniel Ohara¹

¹Materials Department, UC Santa Barbara, Santa Barbara, CA 93106-5050, USA.

Science Advances

|July 20, 2022

Summary

Cadmium arsenide thin films can act as topological insulators. Researchers used quantum capacitance to identify key signatures of this phase, enabling control over Dirac nodes for future topological devices.

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Fabricating van der Waals Heterostructures with Precise Rotational Alignment

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Published on: July 5, 2019

Area of Science:

Condensed Matter Physics
Materials Science
Quantum Phenomena

Background:

Bulk cadmium arsenide is a 3D Dirac semimetal.
Thin films of cadmium arsenide can exhibit 3D topological insulator properties.
Distinguishing topological phases experimentally can be challenging.

Purpose of the Study:

To identify direct experimental signatures of 3D topological insulator physics in cadmium arsenide heterostructures.
To demonstrate a method for controlling the energy of Dirac nodes on the surfaces of these materials.

Main Methods:

Utilizing quantum capacitance measurements on cadmium arsenide-based heterostructures.
Analyzing experimental data for signatures of an insulating bulk and a non-dispersing zero-energy Landau level.
Employing epitaxial heterostructures to engineer surface properties.

Main Results:

Identified two direct experimental signatures of 3D topological insulator physics: an insulating bulk and a zero-energy Landau level insensitive to magnetic fields.
Demonstrated control over the energy of Dirac nodes on each surface of the cadmium arsenide heterostructures.
Established a route for engineering tunable topological insulator phases.

Conclusions:

Quantum capacitance provides a powerful tool for identifying 3D topological insulator states.
Cadmium arsenide heterostructures offer a promising platform for engineering tunable topological insulators.
These findings open new avenues for developing novel topological electronic devices.