Nonlinear Hall effect as a local probe of plasmonic magnetic hot spots

TL;DR

This paper introduces a novel method to directly measure magnetic hot spots in plasmonic nanostructures by using a graphene ribbon to detect nonlinear Hall voltages induced by localized magnetic fields.

Contribution

It proposes a new technique employing graphene ribbons to measure magnetic fields in plasmonic hot spots via nonlinear Hall effects, enabling direct magnetic field detection at high frequencies.

Findings

Nonlinear Hall voltage correlates with magnetic hot spot intensity.

Graphene ribbons can serve as local magnetic field sensors.

Method applicable across a broad spectral range.

Abstract

Recently developed plasmonic nanostructures are able to generate intense and localized magnetic hot spots in a large spectral range from the terahertz to the visible. However, a direct measurement of the magnetic field at the hot spot has not been performed yet, due to the absence of magnetic field detectors that work at those high frequencies and that fit the hot-spot area. We propose to place a graphene ribbon in the hot spot of a plasmonic nanostructure driven by a laser beam, such that a current is generated due to both the magnetic field at the hot spot and the electric field of the laser. We demonstrate that a nonlinear Hall voltage, which can be measured by standard electrical means, builds up across the ribbon, making it possible to directly probe the magnetic field at the hot spot.