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Gura Humorului, Romania

Tanase S.I.,Stefan Cel Mare University of Suceava | Tanase S.I.,Alexandru Cel Bun College | Tanase D.,Stefan Cel Mare University of Suceava | Dobromir M.,Al. I. Cuza University | And 2 more authors.
Journal of Superconductivity and Novel Magnetism | Year: 2016

The effect was investigated of nitrogen impurities on the morphology and magnetoresistance properties of Co–N and Ni–N thin films. The films were electroplated onto aluminum substrates, at room temperature, using the same electrodeposition parameters (pH = 3 and temperature 30 ∘C) for all experiments. The films were compared with similar samples obtained in the absences of nitrogen impurities. Scanning electron microscopy, X-ray photoelectron spectroscopy, and magnetoresistance measurements were utilized to characterize the studied films. The presence of nitrogen in the electrodeposited films have a significant influence on the morphology and magnetoresistance of electrodeposited films. Incorporation of a small amount of nitrogen into electrodeposited films increases the magnetoresistance up to 0.21 % for Co–N thin films and respectively 0.65 % in the case of Ni–N films. We suppose that the shape of the magnetoresistance curves is influenced by the interaction between the magnetic moment of the neighboring Co or Ni grains (with ferromagnetic behavior) separated by the nonmagnetic regions. Interfacial complexities of a ferromagnetic metal/oxide interface in studied thin films could force the interfacial spins to align ferromagnetically or antiferromagnetically. They could be useful for technological applications in electronics. © 2015, Springer Science+Business Media New York. Source


Tanase S.I.,Al. I. Cuza University | Tanase S.I.,Stefan Cel Mare University of Suceava | Tanase S.I.,Alexandru Cel Bun College | Tanase D.,Al. I. Cuza University | And 3 more authors.
Journal of Superconductivity and Novel Magnetism | Year: 2012

The surface morphology and magnetic properties of Co-Ni-N thin films electrodeposited under an external magnetic field were investigated. The films were electroplated on Al substrates using the same electrodeposition parameters (temperature and pH) for all experiments, with an external magnetic field of 107 Oe applied to the cathode surface. The films were compared with similar samples obtained in the absences of magnetic field. The magnetoinduced modifications in the Co-Ni-N morphology can be explained by the specific local convection of ions at the interface cathode-electrolyte, which promotes changes both in the electrical charge of the double layer and in the thickness of the diffusion layer. From the magnetic measurements, we found that the coercivity varied between Hc = (14 ÷ 27) kA/m depending on the direction of the applied magnetic field and on the sodium nitrate content in the plating bath. It was observed that an induced anisotropy ap- peared in the Co-Ni-N films due to the preferential orientation of the easy axis of magnetization in the magnetic field direction. In addition, the Co-Ni-N alloy films showed good magnetic property, which is considered that not only the smaller grain size of the films, but also more uniform surface of the films than that deposited in absence of applied magnetic field. © Springer Science+Business Media, LLC 2012. Source


Pinzaru D.,Al. I. Cuza University | Tanase S.I.,Al. I. Cuza University | Tanase S.I.,Alexandru Cel Bun College | Pascariu P.,Al. I. Cuza University | And 3 more authors.
Optoelectronics and Advanced Materials, Rapid Communications | Year: 2011

We report in this paper the first observation of giant magnetoresistance as high as 23% in electrodeposited [Fe/Pt]n granular multilayers with different thicknesses of bi-layers. [Fe/Pt]n multilayers were prepared by electrodeposition, through the single bath technique. Cu (100) textured polycrystalline foils were used as substrate. The composition of the studied samples is Cu:Pt(x nm)/[Fe(tFe nm)/Pt(x nm)]n, in which the thickness of the iron layer varied between 2.5÷12.5 nm while the thickness of the non-magnetic Pt layer is varied by changing the bottom Pt layer thickness x between 0.5÷3.0 nm. The SEM characterization of the multilayer revealed a granular structure of the deposit with the granule diameter in the range from 2 to 11 nm. These results are comparable with those obtained by the X-ray diffraction measurements of crystallites size obtained by the Scherer equation. The hysteresis loops showed that the magnetic properties are influenced both by the thickness of the bi-layer and by the number of periods (n). The coercivity (Hc) varied in the range 8÷21 kA-1 and the remanence ratio was M/Ms = 0.23÷0.81. The samples display out of plane anisotropy and anti-ferromagnetic type coupling between layers, as it was emphasized by means of the torsion magnetometer. [Fe/Pt]n electrodeposited multilayers display giant magnetoresistance effect which can be explained mainly by the exchange interaction among neighbouring layers and by the spatially inhomogeneous magnetic structure of the granular multilayer (favouring spin scattering at the interfaces between grains and layers). Source


Tanase S.I.,Al. I. Cuza University | Tanase S.I.,Alexandru Cel Bun College | Tanase D.P.,Al. I. Cuza University | Dobromir M.,Al. I. Cuza University | Georgescu V.,Al. I. Cuza University
Applied Surface Science | Year: 2011

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 0-25 at% 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 25 at% 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. © 2011 Elsevier B.V. All rights reserved. Source


Pinzaru D.,Al. I. Cuza University | Tanase S.I.,Al. I. Cuza University | Tanase S.I.,Alexandru Cel Bun College | Pascariu P.,Al. I. Cuza University | And 3 more authors.
Journal of Superconductivity and Novel Magnetism | Year: 2011

In this paper, we report experimental results concerning the magnetic properties and the magnetoresistance effect of [Fe/Pt] n and [Pt/Fe] n electrodeposited multilayers. Two series of multilayers starting with Pt and Fe layers, respectively, were grown onto glass substrate covered with electroless deposited amorphous Ni. We investigated the effect of the seed layer (Pt or Fe) and Pt layer thicknesses on the magnetic and magnetoresistance properties of electrodeposited multilayers. The structure and morphology of the samples were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The hysteresis loops of the [Fe/Pt] n and [Pt/Fe] n multilayers showed that the magnetic properties strongly depend on the Pt thickness and on the seed layer (the first layer deposited onto the glass substrate). [Fe/Pt] n and [Pt/Fe] n electrodeposited multilayers display magnetoresistance (∼15%) effect which can be explained mainly by the spin-dependent scattering of conduction electrons between Fe layers through a Pt layer and by the existence of anti-ferromagnetic coupling between subsequent Fe layers. The existence of a GMR effect in Fe/Pt multilayers is very promising for technological applications (e.g., magnetoresistance sensors). © 2011 Springer Science+Business Media, LLC. Source

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