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MA: Magnetismus

MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)

MA 14.54: Poster

Dienstag, 25. März 2003, 15:15–19:15, Zelt

NiMn/NiFe EB SYSTEMS - MAGNETIC CHARACTERISTICS BEHAVIOUR CLOSE TO THE PHASE TRANSITION POINT OF THE AFM LAYER — •S. Groudeva-Zotova^1,2, D. Elefant¹, R. Kaltofen¹, and C.M. Schneider¹ — ¹IFW-Dresden, PF270016, D-01171 Dresden — ²IE-BAS, Sofia, BG

This work investigates the possibility for accelerating the long post-deposition annealing procedure typically used in the case of NiMn-based spin-valve systems for reaching the afm state in the NiMn pinning film. It includes an investigation of the magnetic and the structural characteristics of the exchange biasing system NiMn/NiFe in a case, when an annealing of samples for very short time at temperatures in the vicinity of the phase transition point of the NiMn film has been made. Both the magnetic measurements and the XRD data show a clear difference between the samples annealed at temperatures below and above 325^∘C, confirming the occurrence of a very fast fcc-fct (paramagnetic-antiferromagnetic) phase transition close to this temperature. The absence of an EB effect and the enhanced coercivity of the samples annealed at lower temperatures is correlated to the dominance of the fcc paramagnetic NiMn phase. In contrast, the significant EB effect measured in the samples annealed at T_an > 325^∘C and the saturation of H_EB found for T_an ≥ 375^∘C is correlated with the presence of a stable afm fct NiMn phase above this temperature.