Tuning chiral anomaly signature in a Dirac semimetal via fast-ion implantation

TL;DR

This study demonstrates that high-energy ion implantation can significantly enhance the chiral anomaly signature, specifically the negative longitudinal magnetoresistance, in Nb-doped Cd$_3$As$_2$ Dirac semimetal thin films, opening new avenues for topological quantum materials.

Contribution

It introduces the novel use of fast-ion implantation to tune and enhance the chiral anomaly signature in Dirac semimetals, which was previously unexplored.

Findings

Maximum NLMR increased by over 100% in doped films

Surface doping yields maximum NLMR around 7 T

Bulk doping yields maximum NLMR over 9 T

Abstract

Cd$_3$As$_2$ is a prototypical Dirac semimetal that hosts a chiral anomaly and thereby functions as a platform to test high-energy physics hypotheses and to realize energy efficient applications. Here we use a combination of accelerator-based fast ion implantation and theory-driven planning to enhance the negative longitudinal magnetoresistance (NLMR)--a signature of a chiral anomaly--in Nb-doped Cd$_3$As$_2$ thin films. High-energy ion implantation is commonly used to investigate semiconductors and nuclear materials but is rarely employed to study quantum materials. We use electrical transport and transmission electron microscopy to characterize the NLMR and the crystallinity of Nb-doped Cd$_3$As$_2$ thin films. We find surface-doped Nb-Cd$_3$As$_2$ thin films display a maximum NLMR around $B = 7$ T and bulk-doped Nb-Cd$_3$As$_2$ thin films display a maximum NLMR over $B = 9$ T--all while maintaining crystallinity. This is more than a 100% relative enhancement of the maximum NLMR compared to pristine Cd$_3$As$_2$ thin films ($B = 4$ T). Our work demonstrates the potential of high-energy ion implantation as a practical route to realize chiralitronic functionalities in topological semimetals.