OPTICAL GENERATION OF MAGNONS BY DIRECT SPIN-MAGNON RELAXATION IN MnF2 : Er3+ G. J. Jongerden, A. J. Kil, J. I. Dijkhuis, A. F.M. Arts et H. W. de WijnJ. Phys. Colloques, 46 C7 (1985) C7-241-C7-245DOI: https://doi.org/10.1051/jphyscol:1985744