Magnetic properties and magnetoresistance effect in Co/Au, Ag nano‐structure films produced by pulse electrodeposition

Abstract

We have investigated the relationship between the magnetism and the magnetoresistance effect in the Co/Au, Ag multilayer films with layers produced in the atomic level by pulse electrodeposition method. The magnetoresistance effect is dependent on both the thickness of Co ferromagnetic layer and Ag,Au non-magnetic layers. The magnetization of these films shows the minimum value against the Ag and Au layer thickness. The Ag and Au layer thickness showing the maximum of MR ratio is not of necessary in agreement with the Ag and Au layer thickness showing the minimum of magnetization. Antiparallel alignment of magnetic spin is a necessary but not sufficient condition in order to generate the GMR of multilayer films. For the Co/Au multilayer films, the Au layer thickness showing the minimum of the magnetization shifts to higher side of the Au layer thickness. IntroductionThe studies on the physical properties of the nano-ordered multilayer films have attracted much attention not only in the fundamental physics, but also in electronic engineering. The productions of multilayered films have been attempted actively by the several methods. Though the electrodeposition is not by no means easy to find a suitable condition for deposition, it has a significance as a useful means to prepare the nano-ordered thin films, even if the suitable deposition condition could be established successfully. Furthermore, it becomes a very useful method for the development of the research in nano-ordered multilayered films with the combination of ferromagnetic and non-magnetic layers, which shows the giant magnetoresistance effect [1][2][3]. It is possible to control the film composition, thickness of multilayer and grain size in an atomic order by regulating the pulse amplitude and width [4][5][6][7]. If the pulse width of deposition time to produce multilayers is reduced to very small values, the multilayer film with layers of two different atomic compositions eventually results in a binary alloy of solid solution type mixed in the atomic level.In this present work, we have investigated the relationship between magnetism and magnetoresistance effect in the Co/Au, Ag films with layers produced in the atomic level by pulse electrodeposition method.

Study of magnetic anisotropy and magnetoresistance effects in ferromagnetic Co/Au multilayer films prepared by oblique incidence evaporation method

“…It is clear that these multilayers have a well-defined periodicity, D ¼ 31 Å , calculated by using the Bragg-law. This layer thickness is in agreement with our mass measurement data obtained from the highly sensitive microbalance and energy dispersive X-ray analysis (EDAX) [4]. Fig.…”

Magnetotransport Properties of Co-Au Granular Alloys

“…The increase in the MR ratio near 30 at % Co seems to be due to the optimum size and distribution of Co grains and inter-granular separation [44], [37]. The low MR values below 30 at% Co can be ascribed to a relatively low concentration of ferromagnetic components leading to fewer magnetic and non-magnetic interfacial scattering sites.…”

“…Guo et al [35] reported room temperature MR of 0.5 % for the as-deposited Co-Au alloys and of up to 1.5 % when annealed at 573 K. They found that the grain size of Co increased with the increase of annealing temperature. Previous studies [37], [38] have shown GMR values of up to 4 % for the as-deposited Co/Au multilayers prepared using pulsed-current electrodeposition in the cyanide solution and demonstrated how closely GMR and magnetic properties are correlated with the layer thickness and composition in the as-deposited Co/Ag and Co/Cu nanostructures [38], [39]. However, it is not yet fully clear to what extent deposition current density, annealing, and layer thickness have an effect on the grain size and on the electrical and magnetic properties of Co-Au alloys.…”

Ferromagnetic Multilayers: Magnetoresistance, Magnetic Anisotropy, and Beyond

“…The various possible parameters used for the fabrication of the Co/Cu, Co/Au and Co/Ag multilayers are listed in Table 1. Pulsed-current deposition method have been used by us and several others to deposit multilayered structures of nano-dimension of Co-Cu, Co-Au and Co-Ag and the typical deposition conditions used are respectively outlined in [60,97,105,107,[112][113][114][115] and [64,67,103].…”