Phonon Superradiance and Phonon Laser Effect in Nanomagnets

We show that the theory of spin-phonon processes in paramagnetic solids must take into account the coherent generation of phonons by the magnetic centers. This effect should drastically enhance spin-phonon rates in nanoscale paramagnets and in crystals of molecular nanomagnets.

Figure 1

(a) ${\rm Y}$ for rectangular geometry; (b) $\widetilde{{\rm Y}}$ for the film and prism geometries. $L_{\alpha }=b_{\alpha }L$, $\alpha =x,y,z$.