Magnetic Field Induced Quantum Metric Dipole in Dirac Semimetal Cd3As2

TL;DR

This paper demonstrates that an external magnetic field can tune the quantum metric dipole in nonmagnetic Dirac semimetal Cd3As2, inducing a nonlinear Hall effect and revealing new ways to engineer nonlinear magnetotransport.

Contribution

It shows for the first time that the quantum metric dipole in a nonmagnetic topological semimetal can be externally controlled by a magnetic field to produce a nonlinear Hall response.

Findings

Magnetic field actively tunes the quantum metric dipole in Cd3As2.

A nonlinear planar Hall effect emerges with increasing magnetic field.

The quantum metric dipole evolution explains the nonlinear Hall response.

Abstract

The quantum geometry, comprising Berry curvature and quantum metric, plays a fundamental role in governing electron transport phenomena in solids. Recent studies show that the quantum metric dipole drives scattering-free nonlinear Hall effect in topological antiferromagnets, prompting the questions of whether this effect can occur in nonmagnetic systems and be externally tuned by a magnetic field. Our work addresses these frontiers by demonstrating that the quantum metric dipole is actively tuned by an external magnetic field to generate a time-reversal-odd nonlinear Hall response in a nonmagnetic topological Dirac semimetal Cd3As2. Alongside the well-known chiral-anomaly-induced negative longitudinal magnetoresistance, an exotic nonlinear planar Hall effect emerges with increasing magnetic field. Careful scaling analysis indicates that this nonlinear planar Hall effect is controlled by the magnetic-field-modulated quantum metric dipole. Constructing a k.p effective model of the Dirac bands under Zeeman and orbital coupling, we derive the evolution of the quantum metric dipole as a function of the magnetic field, providing a comprehensive explanation of the experimental results. Our results establish a band-structure-based strategy for engineering nonlinear magnetotransport in nonmagnetic materials via the quantum metric dipole, opening a pathway toward magnetic-field-tunable nonlinear quantum devices.