Ultrafast nonlinear Hall effect in black phosphorus

TL;DR

This paper reports the observation of an ultrafast nonlinear Hall effect in black phosphorus induced by femtosecond light pulses, enabling rapid light-to-current conversion without magnetic fields.

Contribution

It demonstrates a new ultrafast nonlinear Hall effect in centrosymmetric black phosphorus through dynamical symmetry breaking with femtosecond pulses.

Findings

Ultrafast NHE observed for specific light polarization

NHE persists over 300 femtoseconds

Provides microscopic understanding via spectroscopy and ab-initio calculations

Abstract

The nonlinear Hall effect (NHE) is a recently discovered member of the Hall effect family in which the Hall voltage shows a nonlinear behavior when a transverse electric field is applied. While the NHE does not require broken time-reversal symmetry, such as that induced by a magnetic field, it requires broken inversion symmetry, which limits the range of suitable systems and potential applications. Here, we demonstrate an ultrafast NHE in centrosymmetric black phosphorus through dynamical symmetry breaking using femtosecond light pulses. We provide a detailed microscopic picture of excited carrier dynamics and induced fields using momentum-resolved photoemission spectroscopy combined with \textit{ab-initio} calculations. The ultrafast NHE is observed exclusively for the light polarization aligned with the armchair high-symmetry direction and persists over 300 fs, which opens new possibilities for selective and ultrafast light-to-current conversions.