Geometric oscillations of local Hall and Nernst effects in ballistic graphene at weak magnetic fields

TL;DR

This paper predicts a new type of magnetotransport oscillations in ballistic graphene rings caused by geometric effects, which are robust at room temperature and useful for thermoelectric applications.

Contribution

It introduces a novel class of geometric oscillations in local Hall and Nernst effects in ballistic graphene rings, analytically derived for the first time.

Findings

Oscillations depend on magnetic field and probe positions.

Resonances occur at specific geometric conditions.

Effect remains robust at room temperature.

Abstract

We predict a novel class of magnetotransport oscillations in ballistic graphene specific for a ring-shape geometry. Using the B\"uttiker-Landauer formalism, we analytically obtain the local Hall and Nernst coefficients in the weak-field ballistic regime. These coefficients exhibit pronounced oscillations as functions of both the magnetic field and the angular positions of the measurement probes. The oscillations originate from the discrete set of skipping orbits that geometrically connect the contacts, with resonances occurring when the angular separation between contacts times the radius of the disk equals an integer number of cyclotron diameters. Unlike conventional quantum oscillations in conductivity, this effect is robust at room temperature and can dominate local thermoelectric signals. This geometric control of ballistic flow provides a platform for studying electron hydrodynamics and engineering phase-coherent devices, with potential applications in sensitive terahertz detectors and thermal management systems.