Magnetic properties and giant magneto-impedance effects of FeCuNbSiB single layered and sandwiched films

Magnetic properties and giant magneto-impedance (GMI) effects of Fe73.5CU1N b3Si13.5B9 Single layered films and sandwiched films using Cu or Ag as the central layer prepared by radio frequency sputtering are investigated. The as-deposited single layered films are in amorphous state. The domain struct ures of single layered films annealed at 380 degrees C show that the films are in nanocrystalline state with homogeneous magnetization. The samples po ssess excellent soft magnetic properties and have the maximum values of GMI effects, the maximum GMI ratios are 18% and 14% in longitudinal and transv erse fields, respectively, at 13 MHz. Sandwiched films in the as-deposited state possess large GMI effects, the maximum GMI ratios of sandwiched films with a Cu central layer are 32% and 11% for longitudinal and transverse ca ses, respectively, and those of sandwiched films with a Ag central layer ar e 47% and 57% for longitudinal and transverse cases, respectively. Sandwich ed films using Cu as the inner layer annealed at 250 degrees C exhibit larg e magneto-inductance effect at low frequencies. The maximum magneto-inducta nce ratio is 1733% at 100 kHz.