Hydrogen induced changes of the interlayer coupling in Fe-(3)/V-(x) superlattices (x = 11-16)

The effect of hydrogen on the magnetic exchange coupling between iron layer s through vanadium spacer layers has been studied with magneto-optical Kerr effect experiments in Fe-(3)/V-(x) superlattices. Here x refers to the num ber of V monolayers varying from 11 to 16 and the Fe layer thickness is fix ed at three monolayers. Without hydrogen the superlattice is antiferromagne tic (AFM) for x between 12 and 14 and ferromagnetic (FM) in all other cases . With hydrogen loading the coupling can be switched from AFM to FM and vic e versa. As previously observed with neutron reflectivity measurements (Hjo rvarsson et al., Phys. Rev. Lett. 79 (1997) 901) the change of the interlay er coupling upon hydrogen uptake is not simply due to the expansion of the non-magnetic vanadium spacer layer but more likely to the distortion of the Fermi surface. Bilinear and biquadratic exchange couplings can be recogniz ed by the magnetic hysteresis loops and their coupling energies have been e xtracted by fits to the curves. For all samples the easy axis of the magnet ization is in the plane without any preferred in-plane direction. Hydrogen loading does not affect the magnetic anisotropy of these samples. (C) 1999 Elsevier Science B.V. All rights reserved.