Research: Magnon Drift Currents

The collaboration between groups from ETH Zürich, Universidad Autónoma de Madrid, University of Konstanz, and TU Dresden has resulted in the article “Control of Nonlocal Magnon Spin Transport via Magnon Drift Currents” published in Physical Review Letters. The publication has been highlighted as Editors’ suggestion and featured in Physics with a Viewpoint article.

Electricity and electric currents are the backbone of modern technology. Electric currents can be pictures as a cloud of charged particles (electrons) moving in a given direction. The motion of charged particles can be easily controlled, as they are attracted or repelled by the poles of a battery. Today, we are thus experts in the use of electric currents.

But what if one wants to move particles that do not have an electric charge? This is the situation in magnetic insulators, which feature ferromagnetic order but no mobile charges. In these systems, the elementary excitations of the magnetization, so-called magnons, again form a cloud of particles that is chargeless in contrast to electrons.

The emerging paradigm of magnonics is based on magnons because they manifest unique bosonic properties, not admitted by electrons. However, in order to drive a magnon current, a scheme allowing to steer a cloud of uncharged magnon particles in a given direction must be devised. The article proposes a concept to do so backed by theory and provides the experimental demonstration.

R. Schlitz, S. Vélez, A. Kamra, C.-H. Lambert, M. Lammel, S. T. B. Goennenwein, P. Gambardella,
Control of Nonlocal Magnon Spin Transport via Magnon Drift Currents,
Phys. Rev. Lett. 126, 257201 (2021) (arXiv)