Magnetically induced nonlinear diagnostic features of Fe-Co-Si-B metallic glasses

We investigate the influence of an external magnetic field on optical photo induced second-harmonic generation (PISHG) in Fe18Co60Si9B13 metallic glass . A correlation between the output PISHG signal and degree of crystallinity (varied by thermoannealing) is observed. The applied magnetic field essent ially suppresses the relaxation time of the PISHG. Strong angular dependenc e of the output PISHG signal reflects the peculiarities of phase synchronis m conditions that exist in certain types of glass as a result of light scat tering on grains. Saturation of the PISHG at magnetic fields higher then 0. 75 T indicates correlation between the magnetically induced ordering and no ncentrosymmetry electron-charge density appearance. Comparison of PISHG wit h x-ray diffraction results indicates that the PISHG results have higher se nsitivity to hyperfine magnetic ordering. A possible origin of the observed phenomena is explained on the basis of phenomenological and microscopic ap proaches. (C) 1999 Optical Society of America. OCIS codes: 190.0190, 190.72 20, 210.3820, 160.2750.