Quantum Metric Nonlinear Hall Effect in a Topological Antiferromagnetic Heterostructure

Quantum geometry - the geometry of electron Bloch wavefunctions - is central to modern condensed matter physics. Due to the quantum nature, quantum geometry has two parts, the real part quantum metric and the imaginary part Berry curvature. Berry curvature has led to countless breakthroughs, ranging from the quantum Hall effect in 2DEGs to the anomalous Hall effect (AHE) in ferromagnets. In contrast, the quantum metric has rarely been explored. In this talk, I will report a new nonlinear Hall effect induced by quantum metric dipole by interfacing even-layered MnBi2Te4 with black phosphorus. This nonlinear Hall effect switches direction upon reversing the AFM spins. It exhibits distinct scaling demonstrating the non-dissipative nature. Like the AHE brought Berry curvature under the spotlight, our results open the door to discovering quantum metric responses. Moreover, our data suggests that the AFM can harvest wireless electromagnetic energy, enabling applications that bridges nonlinear electronics with AFM spintronics.<br/> <br/>A. Gao et al. Quantum metric nonlinear Hall effect in a topological antiferromagnetic heterostructure. <i>Science</i> <b>381, </b>181 (2023)