COMPETITION BETWEEN DIRECT EXCHANGE AND INDIRECT RKKY COUPLING IN FE V (001) SUPERLATTICES/

Fe 10 Angstrom/V t(V) (001) superlattices are prepared by magnetron sp utter deposition and characterized using x-ray diffraction (XRD), magn eto-optical Kerr effect (MOKE) magnetometry, and x-ray magnetic circul ar dichroism (XMCD). MOKE loops show three peaks in saturation field a s a function of t(V), indicating RKKY induced AF coupling at t(V) =22 Angstrom, 32 Angstrom, and 42 Angstrom. The expected AF coupling peak at 12 Angstrom, however, is missing. XMCD measurements show that the V layers carry a relatively large magentic moment which extends surpris ingly far from the Fe/V interface. Such 'transient ferromagentism' sug gests a strong V-V direct exchange coupling within the V layer. We arg ue that the V-V direct exchange coupling suppresses the 12 A AF coupli ng peak, but since direct exchange coupling decays more quickly than R KKY coupling, the AF peaks at 22, 32, and 42 Angstrom are observed.