A quantum framework for negative magnetoresistance in multi-Weyl semimetals

Area of Science:

• Condensed matter physics
• Quantum materials science

Background:

• Multi-Weyl semimetals exhibit unique electronic properties due to higher-order Weyl nodes.
• The chiral anomaly in Weyl semimetals links topology to observable transport phenomena.

Purpose of the Study:

• To develop a quantum mechanical theory for negative magnetoresistance in multi-Weyl semimetals under parallel electric and magnetic fields (E ∥ B).
• To elucidate the role of chiral anomaly and Landau quantization in magnetotransport phenomena.

Main Methods:

• Formulation of a quantum theory incorporating Landau quantization and chiral anomaly effects.
• Analysis of the impact of higher-order Weyl nodes and their associated chiral Landau levels on conductivity.
• Investigation of the influence of disorder scattering on bulk Landau levels.

Main Results:

• Negative magnetoresistance is explained by the discrete evolution of chiral Landau levels crossing the Fermi energy with increasing magnetic field.
• This quantized evolution leads to step-like changes in longitudinal conductivity, serving as a signature of multi-Weyl topology.
• Anomaly-driven transport dominates over bulk Landau level contributions, except at very low magnetic fields.

Conclusions:

• A unified quantum framework explains negative magnetoresistance in multi-Weyl semimetals, attributing it to Landau quantization and impurity scattering.
• The study provides a direct experimental signature for identifying multi-Weyl topological phases.
• The findings move beyond semiclassical descriptions to a fully quantum-mechanical understanding of anomaly-related transport.