Magnetic properties and static–dynamic magnetostrictive characteristics for SmFe2/Fe exchange-coupled multilayers

Giant magnetostrictive SmFe2/Fe exchange-coupled multilayers were fabricated by ion beam sputtering deposition on glass substrates. The effects of SmFe2/Fe exchange coupling action and vacuum annealing on soft-magnetic property and static-dynamic magnetostrictive characteristics of SmFe2/Fe multilayers were investigated. The results showed that the soft-magnetic, static–dynamic magnetostrictive characteristics were greatly improved by SmFe2/Fe exchange coupling action and proper vacuum annealing treatment temperature. Compared with that of SmFe2 single film, the coercivity in the direction of easy magnetization axis for SmFe2/Fe exchange-coupled multilayers exhibited a greater decrease. Better soft-magnetic properties were achieved (Hc=2.54kA/m, Ms=120.38emu/g, and Mr/Ms=0.21) after vacuum annealing at certain temperature. The magnetostrictive coefficient for SmFe2/Fe exchange-coupled multilayers was about 135ppm at 16kA/m magnetic field. At first order resonant frequency (99.2Hz), the amplitude peak–peak value for the as-deposited SmFe2/Fe exchange-coupled multilayers was 46μm. After the vacuum annealing treatment at 250°C, the amplitude peak–peak value increased to 650μm.