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

We investigate the influence of an external magnetic field on optical photoinduced 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 essentially suppresses the relaxation time of the PISHG. Strong angular dependence of the output PISHG signal reflects the peculiarities of phase synchronism conditions that exist in certain types of glass as a result of light scattering on grains. Saturation of the PISHG at magnetic fields higher then 0.75 T indicates correlation between the magnetically induced ordering and noncentrosymmetry electron-charge density appearance. Comparison of PISHG with x-ray diffraction results indicates that the PISHG results have higher sensitivity to hyperfine magnetic ordering. A possible origin of the observed phenomena is explained on the basis of phenomenological and microscopic approaches. (C) 1999 Optical Society of America. OCIS codes: 190.0190, 190.7220, 210.3820, 160.2750.