Negative magnetoresistance in Dirac semimetal Cd3As2.

Hui Li,Hongtao He,Huachen Zhang,Zhiyong Fan,Hongchao Liu,Jiannong Wang,Shun-Qing Shen,Hai-Zhou Lu,Rong Ma

doi:10.1038/ncomms10301

Abstract

A large negative magnetoresistance (NMR) is anticipated in topological semimetals in parallel magnetic fields, demonstrating the chiral anomaly, a long-sought high-energy-physics effect, in solid-state systems. Recent experiments reveal that the Dirac semimetal Cd3As2 has the record-high mobility and positive linear magnetoresistance in perpendicular magnetic fields. However, the NMR has not yet been unveiled. Here we report the observation of NMR in Cd3As2 microribbons in parallel magnetic fields up to 66% at 50 K and visible at room temperatures. The NMR is sensitive to the angle between magnetic and electrical fields, robust against temperature and dependent on the carrier density. The large NMR results from low carrier densities in our Cd3As2 samples, ranging from 3.0 × 1017 cm−3 at 300 K to 2.2 × 1016 cm−3 below 50 K. We therefore attribute the observed NMR to the chiral anomaly. In perpendicular magnetic fields, a positive linear magnetoresistance up to 1,670% at 14 T and 2 K is also observed.

Highlights

A large negative magnetoresistance (NMR) is anticipated in topological semimetals in parallel magnetic fields, demonstrating the chiral anomaly, a long-sought high-energy-physics effect, in solid-state systems
The chiral anomaly arises because of the nontrivial Berry curvature, which diverges at the Weyl nodes, so the Fermi energy EF has to be as close to the Weyl nodes as possible for a clear signal of the negative MR
We note that similar R–T curves were observed in recent studies of Dirac semimetals, where chiral anomaly induced transport features were reported[40,41]

Summary

Introduction

A large negative magnetoresistance (NMR) is anticipated in topological semimetals in parallel magnetic fields, demonstrating the chiral anomaly, a long-sought high-energy-physics effect, in solid-state systems. Recent experiments reveal that the Dirac semimetal Cd3As2 has the record-high mobility and positive linear magnetoresistance in perpendicular magnetic fields. 16) and TaAs (refs 17–21)), the Dirac semimetal Cd3As2 (refs 22–27) has peculiar transport properties, such as a giant MR in perpendicular magnetic fields and record-high mobility[28,29,30,31,32,33], is of great potential in device applications. Our analysis reveals a characteristic carrier density dependence of the observed negative MR that is in agreement with the semiclassical theory about the chiral anomaly in topological semimetals. By studying the carrier density dependence of the observed linear MR in perpendicular magnetic fields, possible physical origins are discussed. Our work shows that the carrier density plays an important role in the observation of the negative and linear MR and their magnitudes

Methods

Results

Conclusion