Paul Noël
Magnons play a central role in spin transport and current-induced magnetic phenomena in insulating and metallic magnetic systems. In this talk, we will introduce the magnon creation-annihilation magnetoresistances, a new class of magnetoresistive effects appearing in heavy metal/ferromagnet bilayers that provide direct access to current-induced changes in the magnon population.
These magnetoresistances originate from the asymmetric generation and absorption of magnons driven by electrical currents, which induce nonequilibrium changes in the magnon population and result in resistance variations sensitive to both the magnitude and polarity of the applied current. Owing to their nonlinear nature, these effects are efficiently isolated using second harmonic resistance measurements, which allow us to directly quantify how current-induced magnon creation and annihilation modulate the magnetization and magnetotransport. This approach opens new perspectives for the electrical control and detection of magnons in spintronic and magnonic devices.
We will further show that this magnon-mediated contribution critically impacts spin-orbit torque measurements performed using the harmonic Hall technique: neglecting it leads to a substantial overestimation of both damping-like and field-like torques.