Direct Observation of a Phonon Bottleneck Using Brillouin Light Scattering

Abstract

The effective temperature of a narrow band of microwave acoustic phonons in Ni-doped MgO has been observed to rise to ∼60°K while the bulk of the lattice phonons remains at the 2°K bath temperature when the ${\mathrm{Ni}}^{2+}$ spin system is saturated with resonant microwaves.