Magnetic Properties of Coupled Gd/Pd/Ni Thin Films
Magnetic properties of coupled Gd/Pd/Ni thin filmsILIR ZOTO,GARY MANKEY, MINT Center, Department of Physics, University of Alabama— Transition metal-rare earth bilayers might allow magnetizations higher than thatavailable from transition metal if the strong exchange interactions of the transitionmetal layer could be used to raise the Curie temperature of an adjacent, high momentrare earth layer. Literature suggested for a ferromagnetic interaction in the Ni-Gd bulk alloys and an increased moment at room temperature when Gd layer isdeposited onto thin Co and permalloy films. Recently, we found that Ni/Gd bilayerscouple antiferromagnetically at the interface. Adding a spacer layer could changethe coupling behaviour. Here, a study of a Gd(15nm)/Pd(tnm)/Ni(10nm) trilayeris presented with t varying from 0.5 to 2.5nm. The hysteresis loops were measuredwith VSM in the temperature range 5-250K. A Stoner-Wolfarth model simulates thehysteresis loops through the minimization of the energy of the following expression:E=−M₁Ht₁cos(θ₁)−M₂Ht₂cos(θ₂) +K₁t₁sin²(θ₁) +K₂t₂sin²(θ₂)+J₁cos(θ₁−θ₂) +J₂cos²(θ₁−θ₂)where J₁ and J₂ are the bilinear and biquadratic coupling constants. The simulatedloops are in good agreement with the experimental results and confirm the antifer-romagnetic coupling of Ni and Gd layers for t<2.5nm and the disappearance of thecoupling for t>2.5nm.