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The effect of nitrogen addition on the morphology, magnetic anisotropy, and magnetoresistance properties of Co-Ni-N granular thin films were investigated. The films were grown by electrodeposition onto aluminum substrates at room temperature. By a complex process of cationic catalysis occurring at the cathode/electrolyte interface, nitrogen is adsorbed in the Co-Ni film. Finally, a granular film grows by a tridimensional progressive nucleation mechanism. The nature of the grains and of the interface between them influences exchange interactions between grains, which play an important role in determining the magnetic anisotropy. From the magnetic measurements, we found that the magnetic anisotropy constant varied in the range K=(−21.5÷36.6)×10 J⋅m and the coercivity varied between H=(13÷67) kA⋅m depending on the sodium nitrate content in the plating bath. The Co-Ni-N granular thin films display large values (∼160%) of magnetoresistance. These large values of magnetoresistance make such structures attractive for applications as sensitive magnetic field sensors. [ABSTRACT FROM AUTHOR]

Abstract: A series of Co, Ni and Co–Ni granular thin films with variable nitrogen content in the range 0–16at.% N were prepared by electrodeposition onto aluminum substrate. The nitrogen content was varied in order to analyze its influence on the magnetoresistance. The morphology, structure and magnetic properties of electrodeposited Co, Ni and Co–Ni granular thin films were also studied as a function of the nitrogen content. The magnetoresistance (MR) ratio of Co–Ni–N granular films initially increased and then decreased when increasing the nitrogen content. The films exhibit a granular morphology, with rich in nitrogen frontiers between grains and some un-deposited sites on the aluminum substrate, which easily oxidize even during the process of preparation, favoring the spin tunneling transport. We obtained tunneling magnetoresistance (TMR) effect in the Co–Ni–N granular thin films in the range 3–159%; this large effect obtained in Co–Ni–N granular thin films makes them suitable for applications in electronics. [Copyright &y& Elsevier]

Abstract: We present in this paper several results concerning the preparation by means of electrolysis and characterization of Co–Ni–Mo thin films. Co–Ni–Mo thin films with different molybdenum content in the range 0–25at% Mo were prepared from a complex solution containing ions of Co, Ni and Mo, using galvanostatic control, on aluminum substrates. The effects of applied current density on the morphology, magnetic, magnetoresistance, and optical properties of the electrodeposited Co–Ni–Mo films were investigated. The applied current density significantly influenced the film composition and their magnetic properties. The increase of molybdenum content in Co–Ni films (up to 25at% Mo) enhances the resistivity, but it reduces the magnetoresistance effect. We report the first observation of magnetoresistance as high as 8% in Co–Ni–Mo thin films. [Copyright &y& Elsevier]

Abstract: In this work, we report on experimental investigation of the influence of nitrogen addition on magnetic and transport properties of Co–Ni granular films with different nitrogen content correlated with the surface morphology. The granular thin films were electrodeposited on aluminium substrate, from the following base solution: 30g/l CoSO4·7H2O, 50g/l NiSO4·7H2O, 10g/l NiCl2·6H2O, 50g/l Na2SO4·10H2O, 30g/l H3BO3 and 10g/l NaCl. Sodium laurylsulphate (C12H25NaO4S) and sodium saccharine (NaC7H4O3NS·2H2O) were used as additives. As a source for nitrogen inclusion in the films by cationic catalysis, sodium nitrate (NaNO3) was introduced in the electrolyte. The concentration of NaNO3 in electrolytic bath was varied with the aim to control the films nitrogen content. Co–Ni–N/Al granular films display tunneling magnetoresistance (2–160%) effect which could be explained mainly by the elastic spin-dependent scattering of conduction electrons at the interface between magnetic grains (constituted of Co–Ni solid solution) and nonmagnetic regions (rich in N inter-granular frontiers and aluminium oxidized substrate). [Copyright &y& Elsevier]

Abstract: In this report we describe some experimental results concerning the preparation by electrodeposition and characterization of Co/Zn multilayer films, a system of special significance because Co and Zn are immiscible in a large range of compositions, permitting an easier adaptation of the sharp interfaces and the magnetic interactions between layers, with a view to obtain technological applications in nano-electronics. We established the working parameters for electrodeposition of multilayer films based on Co and Zn nanoscale layers, using a dual-bath potentiostatic electrodeposition method. The effect of the first electrodeposited layer growth process on the structure and magnetic properties of the multilayer were studied by using two series of multilayers of varying periods, starting with Co or Zn layers, respectively (with the same total thickness of Co layers, namely 50 layers of 5nm thick, but various Zn layer thickness). These properties were also studied as a function of the Zn layer thicknesses (varying between 0.1nm and 5.9nm), for the two series of films. The magnetoresistance (in the current in plane configuration with dc magnetic field applied in the film plane), varied with Zn layer thickness, exhibiting a giant magnetoresistance contribution of about 30% in the case of [Co (5nm)/Zn (2.7nm)]50 films. [Copyright &y& Elsevier]

In this work, we report experimental results concerning the giant magnetoresistance effect and the magnetic properties of [Ni-Fe/Zn/Co-Ni-N/Ni-Mn] spin-valve sandwich electrodeposited on Cu substrate. The attraction of such granular spin valves is that they can be very easily manufactured, with a view to their application as magnetoresistive material in magnetic field sensors. The granular structure is induced both due to the immiscibility of the diamagnetic Zn layer with the ferromagnetic Co-Ni-N, and to the addition of N impurity in the Co-Ni-N layer. The thickness of the Zn diamagnetic interlayer (varying between 3 nm and 13 nm) plays a significant role on the magnitude of the giant magnetoresistance (GMR) effect, and the magnetic behavior is dependent on this parameter. The magnetoresistance measured in current in plane (CIP) and current perpendicular to plane (CPP) configurations, with dc magnetic field applied in the film plane, varied with Zn interlayer thickness, exhibiting a GMR contribution of about 13% (CIP) and 10% (CPP) in the case of [Ni-Fe(140nm)/Zn(3 nm)/Co-Ni-N(150nm)/Ni-Mn(160nm)] granular spin-valve stack. [ABSTRACT FROM AUTHOR]