Direct measurement of magnon temperature by magneto-optic Kerr effect in YIG

Abstract

Abstract Magnon–phonon thermal relaxation holds a fundamental role in condensed matter physics, and the difference between local phonon and magnon temperature ΔT mp as an important part of this subfield was theoretically considered responsible for the spin Seebeck effect. Experimental determination of ΔT mp is necessary to give more insight into the magnon–phonon coupling. Here we report spatially resolved measurements of magnon temperature performed by magneto-optic Kerr effect in yttrium iron garnet. Our results indicate a strong interaction between magnon and phonon subsystems in YIG with an upper limit of the phonon-magnon thermal relaxation length of 1.4 mm, and means this method is valid.