Ballistic magnon heat conduction and possible Poiseuille flow in the helimagnetic insulator Cu${}_2$OSeO${}_3$

N. Prasai, B. A. Trump, G. G. Marcus +4

We report on the observation of magnon thermal conductivity ${\kappa }_m\sim$ 70 W/mK near 5 K in the helimagnetic insulator Cu${}_2$OSeO${}_3$, exceeding that measured in any other ferromagne…