Negative magnetoresistance in Dirac semimetal Cd3As2

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Topological semimetals are predicted to exhibit large negative magnetoresistance (NMR) in parallel magnetic fields due to the chiral anomaly.
• The Dirac semimetal cadmium arsenide (Cd3As2) is known for high mobility and positive linear magnetoresistance in perpendicular fields.
• Observation of NMR in Cd3As2, confirming the chiral anomaly in a solid-state system, remained elusive until this study.

Purpose of the Study:

• To experimentally investigate and confirm the presence of negative magnetoresistance (NMR) in Cd3As2 microribbons.
• To explore the conditions under which NMR occurs, including magnetic field orientation, temperature, and carrier density.
• To attribute the observed NMR phenomenon to the chiral anomaly in this topological semimetal.

Main Methods:

• Fabrication of Cd3As2 microribbons.
• Electrical transport measurements under varying magnetic field strengths and orientations (parallel and perpendicular) and temperatures.
• Analysis of magnetoresistance dependence on field angle, temperature, and carrier density.

Main Results:

• Observation of significant negative magnetoresistance (NMR) up to 66% in Cd3As2 microribbons under parallel magnetic fields.
• The NMR effect was found to be temperature-robust, observable at room temperature, and dependent on carrier density.
• Low carrier densities (2.2 × 10^16 to 3.0 × 10^17 cm^-3) were measured, consistent with chiral anomaly predictions. Positive linear magnetoresistance up to 1,670% was also observed in perpendicular fields.

Conclusions:

• The study successfully demonstrates large negative magnetoresistance (NMR) in Cd3As2, providing experimental evidence for the chiral anomaly in this material.
• The findings highlight Cd3As2 as a promising platform for exploring high-energy physics phenomena in solid-state systems.
• The observed NMR's sensitivity to experimental conditions and its presence at room temperature open avenues for future research and potential applications.