Abstract
In this study, the fabrication of magnetic multilayers with a controlled value of the in-plane uniaxial magnetic anisotropy field in the range of 12 to 72 kA/m was achieved. This fabrication was accomplished by the deposition of bilayers consisting of an obliquely deposited (54°) 8-nm-thick anisotropic Co layer and a second isotropic Co layer that was deposited at a normal incidence over the first layer. By changing the thickness value of this second Co layer (X) by modifying the deposition time, the value of the anisotropy field of the sample could be controlled. For each sample, the thickness of each bilayer did not exceed the value of the exchange correlation length calculated for these Co bilayers. To increase the volume of the magnetic films without further modification of their magnetic properties, a Ta spacer layer was deposited between successive Co bilayers at 54° to prevent direct exchange coupling between consecutive Co bilayers. This step was accomplished through the deposition of multilayered films consisting of several (Co8 nm-54°/CoX nm-0°/Ta6 nm-54°) trilayers.
Highlights
Considerable research effort has recently been devoted to fabricating new materials that have an optimum response to electromagnetic fields in the ultrahigh frequency (UHF) range
Each of the Co layers was strongly exchange-coupled to the neighbouring layer, and as a consequence of this coupling, the magnetic properties of the bilayer were the weighted average of the magnetic properties of each of the constituent layers [27]
A normally deposited Co layer, whose thickness varied between 1 and 20 nm, that was isotropic. These two layers were strongly exchange-coupled, and because the thickness of this resulting bilayer was smaller than the exchange correlation length for Co, the magnetic properties of the resulting bilayer were an average of the magnetic properties of the individual layers
Summary
Considerable research effort has recently been devoted to fabricating new materials that have an optimum response to electromagnetic fields in the ultrahigh frequency (UHF) range. This effort has been motivated by advancements in electromagnetic devices such as personal computers, palmtop terminals and cell phones. The increasing value of the density of information stored in these drives [1] has required an increase in the rate at which information is written and read from these devices [2] This speed can reach 2 Gbit/s, which forces the hard disk drive heads to perform optimally at frequencies on the order of several gigahertz. The operating frequencies of the mobile phone standards (UMTS) are in the range of frequencies of approximately 0.9 (GSM) or 2.1 GHz (3G)
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