Microstructural and magnetic properties of exchange-coupled Co/Fe multilayers

Abstract

Cobalt/iron multilayers with different layer thickness were electron beam evaporated in ultrahigh vacuum, keeping constant both the number of layers and the Co/Fe thickness ratio. Structural and magnetic properties are thoroughly investigated with different techniques. The multilayers have clean and sharp interfaces. All samples show single-phase magnetic behavior in the temperature range of 5–300 K, due to the strong exchange coupling between the layers. The room temperature hysteresis loops present a sharp switching at a field of ∼8 kA/m, followed by a residual hysteresis extending up to saturation, at fields of several tens of kA/m.

Structural order and magnetic anisotropy transition in Co/Fe multilayers

“…This suggests that a strong exchange interaction between the Co and Fe layers is present. 9 From the line intensity ratios of the Mössbauer spectra, the angles between magnetization and film plane have been deduced. The magnetization substantially lies in the film plane for 5͓Co10/Fe t͔, with tр24 nm, forming an 8°-10°a ngle with respect to the film plane and rises to ϳ37°for 15 nm thickness.…”

Magnetic interactions and interface properties in Co/Fe multilayers

“…No preferred crystallographic orientations were detected. 8 Grazing incidence x-ray reflectivity ͑GIXRR͒ measurements were performed on the Station 9.4 at Synchrotron Radiation Source ͑SRS͒ at Daresbury Laboratory at 298 K. The x-ray beam was focused with a Pt coated toroidal Si mirror. The beam size at the focal point was Ͻ 1 mm.…”

“…4 Using simple materials ͑i.e., iron and cobalt͒ and ultrahigh vacuum e-beam deposition technique we demonstrated the feasibility of planar magnetic nanocomposites involving a dominant soft phase and showing a magnetic energy density superior to that of the hard component. 7,8 It was supposed that, in addition to the high purity of the components and the thickness of the layers ͑chosen in the range of the exchange length͒, the high quality of the obtained interfaces allowed the strong exchange coupling between the ferromagnetic phases.…”

Temperature dependence of in-plane magnetic anisotropy of Co/Fe multilayers

“…r Thin films and multilayers, also non-epitaxially grown, may show an in-plane uniaxial magnetic anisotropy, whose origin is still under debate [1,2]. Co/ Fe multilayers have recently received attention due to their applicability as a model system for studying the magnetic behaviour of exchange-coupled nanocomposites [3].The aim of the present work was to investigate the influence of temperature and Fe layer thickness on the in-plane magnetic anisotropy.A series of Co/Fe multilayers were electron beam evaporated in ultra-high vacuum onto silicon substrates. The samples consisted of 5 Co/Fe bilayers covered by a Co layer.…”

“…r Thin films and multilayers, also non-epitaxially grown, may show an in-plane uniaxial magnetic anisotropy, whose origin is still under debate [1,2]. Co/ Fe multilayers have recently received attention due to their applicability as a model system for studying the magnetic behaviour of exchange-coupled nanocomposites [3].…”