Band Engineering of Dirac Semimetals Using Charge Density Waves.

Area of Science:

• Condensed matter physics
• Materials science
• Solid-state physics

Background:

• Topological matter research relies heavily on discovering new materials like topological insulators, Dirac semimetals, and Weyl semimetals.
• Many existing topological materials have non-ideal band structures, complicating their study and application.
• A significant challenge is the convolution of topological bands with trivial ones and the placement of key features below the Fermi level.

Purpose of the Study:

• To introduce a novel mechanism for designing idealized Dirac semimetals.
• To experimentally validate the proposed mechanism in a specific material.
• To investigate the unique transport properties arising from this design.

Main Methods:

• Theoretical design of topological materials utilizing charge density waves and non-symmorphic symmetry.
• Experimental synthesis and characterization of the antiferromagnetic compound GdSb$_{0.46}$Te$_{1.48}$.
• Analysis of band structures and transport properties to confirm Dirac semimetal behavior and identify unique transport regimes.

Main Results:

• A new mechanism based on charge density waves and non-symmorphic symmetry is proposed for creating idealized Dirac semimetals.
• GdSb$_{0.46}$Te$_{1.48}$ is identified as a nearly ideal Dirac semimetal, with interfering bands suppressed at the Fermi level.
• Unusual transport behavior was observed, suggesting a novel regime where Dirac carriers localize with disorder.

Conclusions:

• The proposed mechanism offers a viable strategy for designing high-quality Dirac semimetals.
• GdSb$_{0.46}$Te$_{1.48}$ serves as an experimental proof-of-concept, demonstrating the effectiveness of the mechanism.
• The observed localization of Dirac carriers in the presence of disorder opens new avenues for understanding topological material physics.