Electrical noise spectroscopy of magnons in a quantum Hall ferromagnet

Abstract

Collective spin-wave excitations-magnons-in a quantum Hall ferromagnet are promising quasi-particles for next-generation spintronics devices, including platforms for information transfer. Detection of these charge-neutral excitations relies on the conversion of magnons into electrical signals in the form of excess electrons and holes, but if these signals are equal the magnon detection remains elusive. In this work, we overcome this shortcoming by measuring the electrical noise generated by magnons. We use the symmetry-broken quantum Hall ferromagnet of the zeroth Landau level in graphene to launch magnons. Absorption of these magnons creates excess noise above the Zeeman energy and remains finite even when the average electrical signal is zero. Moreover, we formulate a theoretical model in which the noise is generated by equilibration (partial or full, depending on the bias voltage) between edge channels and propagating magnons. Our model, which agrees with experimental observations, also allows us to pinpoint the regime of ballistic magnon transport in our device.

References in corpus (10)

• Unconventional quantum Hall effect and Berry's phase of 2pi in bilayer graphene
• Unconventional Integer Quantum Hall effect in graphene
• Fractional Chern insulators in magic-angle twisted bilayer graphene
• Spin Filtered Edge States and Quantum Hall Effect in Graphene
• Tunable Fractional Quantum Hall Phases in Bilayer Graphene
• Nanoscale Detection of Magnon Excitations with Variable Wavevectors Through a Quantum Spin Sensor
• Broadband microwave detection using electron spins in a hybrid diamond-magnet sensor chip
• Observation of ballistic upstream modes at fractional quantum Hall edges of graphene
• Determination of topological edge quantum numbers of fractional quantum Hall phases
• Visualization of moiré magnons in monolayer ferromagnet

Cited by in corpus (5)

• Absence of heat flow in ν = 0 quantum Hall ferromagnet in bilayer graphene
• Fractional quantum Hall coexistence phases in higher Landau levels of graphene
• Half-integer thermal conductance in the absence of Majorana mode
• Landscapes of an out-of-equilibrium anyonic sea
• Spontaneous Breaking of the SU(3) Flavor Symmetry in a Quantum Hall Valley Nematic