Quantum metric nonlinear Hall effect observed for the first time

Quantum nonlinear Hall effect graphsScientific Achievement

CATS researchers observed a new phenomenon, called the quantum metric nonlinear Hall effect, in a topological antiferromagnet.

Significance and Impact

The quantum geometry of electronic bands governs transport properties. The Berry curvature determines the Hall effect and here we show how the quantum metric controls the nonlinear Hall effect. Our results open the door to discovering other quantum metric responses.

Research Details

  • Layered MnBi2Te4 and black phosphorus specimens are prepared with a special symmetry where the Berry curvature vanishes, but the quantum metric is large.
  • The quantum metric Hall effect is controlled by the antiferromagnetic state and changes sign when the magnetic configuration flips.
  • The magnitude and sign of the effect depend on the quantum metric of the band structure and has been predicted by theory.

A. Gao et al., Science 381, 181 (2023). https://www.science.org/doi/10.1126/science.adf1506