TF8:
Magnetic Thin Films and Multilayers
Posters
TF8.1.P
STUDY OF DIFFUSION AT SURFACE OF MULTILAYERED Cu/Au
FILMS ON- MONOCRYSTALLINE SILICON ( 111 )
C. Benazzouz 1, N. Benouattas 2, S. Tobbeche1 and A. Bouabellou 3
1
CRNA, 2 Bd Frantz Fanon, Alger , Algérie
2
Département de Physique, Faculté des Sciences, Université Ferhat-Abbas, Sétif , Algérie
3
Laboratoire des Couches Minces et Interfaces, Université Mentouri, Constantine , Algérie.
Multilayered of pure gold and copper films were evaporated alternatively on (111)
monocrystal silicon substrates. Annealing, in a furnace vacuum, were carried out at 200 ,
400 and 600°C for 30 minutes. The obtained samples were analyzed by means of
Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD) and scanning
electron microscopy (SEM) techniques. The interdiffusion of the different elements and the
thermodynamic transformations at Cu/Au and Au/Si interfaces have been investigated.
Keywords: Gold, silicon, copper silicides, morphology, backscattering spectrometry,
scanning electron microscopy, X-ray diffraction.
Corresponding author: C. BENAZZOUZ
E-mail : benazoz@yahoo.fr
TF8.2.P
THE RELATION BETWEEN THE PLASMA CHARACTERISTIC
AND THE CORROSION PROPERTIES OF TiN/Ti MULTILAYERS
DEPOSITED BY UNBALANCED MAGNETRON SPUTTERING.
M. Flores, and S. Muhl
Instituto de Investigaciones en Materiales, UNAM, Ciudad
Universitaria, Coyoacán, A.P. 70-360, México D.F. 04510 México.
E. Andrade (a) Instituto de Física, UNAM, Ciudad Universitaria, Coyoacán A.P. 20-364
México D.F. 01000, México.
The multilayers were prepared by balanced magnetron sputtering with a concentric
electromagnet coil around the magnetron in order to produce a variable unbalance of the
magnetron, and in this way provide changes in the ion bombardment of the substrate. It was
observed that the additional magnetic field increased the plasma temperature as well as
altering the other plasma characteristics. The field induced changes in the ion bombardment
of the substrate and was found to modify the film microstructure.
In this work monolayers of Ti and multiple TiN/Ti layers on H13 steel and stainless steel
substrates were prepared by reactive magnetron sputtering, with the aim of improving the
corrosion resistance. The ion current density incident on the substrate and the plasma
parameters, such as, the electron temperature, plasma density, floating potential and plasma
potential were studied as a function of the additional magnetic field. In the TiN/Ti
multilayers, the titanium layer helps to reduce the incidence of pinholes, and decreases the
porosity of subsequent TiN coatings by improving the microstructure. The corrosion
resistance of these layers was studied by means of potentiodynamic polarizations in a 0.5 M
NaCl solution. The composition of the films was determined by ion beam techniques. We
report the results of studies of the influence of magnetic field on the plasma parameters and
on the improvement of the corrosion resistance of TiN/Ti multilayers.
TF8.3.P
INFLUENCE OF ION IMPLANTATION ON SOME PROPERTIES OF
MAGNETIC FILMS
ROMANOV I.G., TSAREVA I.N.
Nizhny Novgorod Branch of
Mechanical Engineering Research Institute, RAS.
603024, Nizhny Novgorod, Belinskogo, 85, Russia.
The results of experimental study of the hardness, frictional coefficient electrical
and magnetic properties of thin ferromagnetic films (Ni, Fe, Co, Ni-Fe) after B+, N+, P+
and Ar+ ion implantation are presented. It is shown that the hardness of the films increases
essentially in the case of irradiation by chemically active ions at the doses of D >2.1015 cm2
. The frictional coefficient depends on dose and sort of the bombarding ions. The films
subjected to P+ ion implantation have the lowest values of the frictional coefficient
(amorphous structure). The results obtained are discussed within the framework of the
adhesional – deformation theory of frictional for variation doses.
TF8.4.P
ELECTRODEPOSITED Ni-W MAGNETIC THIN FILMS WITH
COLUMNAR NANOCRYSTALLITES
N. Sulitanu, F. Brînză
Department of Solid State Physics, Faculty of Physics, “Al.I.Cuza” University, Iaşi,
Romania
Nanocrystalline Ni-W thin films (140 nm) containing from zero to 18 wt % W were
electrolitically prepared and structural and magnetic characterized. XRD, SEM and TEM
investigations have revealed that all segregated Ni columns are fcc-type whose [111] axis is
oriented perpendicular to the film plane and have 140 nm in height and 6-27 nm in
diameter. Depending on film composition, two types of nanostructures were observed: (a)
single-phase nanostructure ( 7 wt % W) which consist of nanocrystalline Ni columns (d =
14-27 nm) separated by interfaces or “interphases”, namely W enriched particles
boundaries, and (b) two-phase nanostructure (7-18 wt %) in which a second Ni-W
amorphous phase or even amorphous-disordered mixture separates the magnetic columnar
Ni nanocrystallites (d = 6-14 nm). The 111 columnar crystallites have an easy
magnetization direction along their long axis mainly due to the in-plane internal biaxial
stresses. The saturation magnetization non-linearly decreased with small grain size. The
variation of in-plane coercivity Hc of these phase-separated thin films is typical of singledomain Ni grains and reaches a maximum for 13 wt % W in composition. The magnetic
properties strongly depend on crystallite size and its isolation degree, and their variation is
characteristic for a single-domain magnetic particles. Our investigation finds out that
average crystallite size and its isolation degree can be controlled, and the magnetic
properties optimized, by choosing appropriate Ni-W composition. For example, typical NiW films, 13 wt % W in composition, behave as a system of perpendicular Ni columns 12.5
nm in diameter embedded in an amorphous Ni-W matrix with high perpendicular magnetic
anisotropy, and each crystallite would correspond to one information bit. These kind of
samples exhibit semi-hard magnetic characteristics: saturation magnetization Ms = 419
kA/m, in-plane coercivity Hc = 49 kA/m, Hc = 118 kA/m, quite high squareness ratio S =
0.6 and very high coercivity squareness S* = 0.83. These magnetic characteristics are in
well agreement with the required parameters for a high density magnetic recording
medium.
Corresponding author: Professor N. Suliţanu, Department of Solid State Physics,
Faculty of Physics, “Al.I.Cuza” University, 11 Carol I Blvd.,
RO-6600 Iaşi, Romania
TF8.5.P
EFFECT OF MAGNETIC FLUX DISTRIBUTION ON GMR OF Ag/Co
MULTILAYERS
1
S. Luby, 1E. Majkova, 2V. Áč, 2B. Anwarzai, 1A. Debnarova, 1R. Senderak
1
Institute of Physics, Slovak Academy of Sciences, Bratislava, Slovakia
2
Department of Mechantronics, Unversity of Trenčín, Slovakia
Since the discovery of giant magnetoresistance (GMR) in multilayers (MLs) various
applications of this effect are studied. Attention is paid especially to magnetoresistive readheads and magnetic sensors. One practical aspect of ML structures for sensing elements is
the magnetic field distribution in the direction perpendicular to the surface of ML in the
current-in-plane geometry. It results from the fact that top and bottom ferromagnetic layers
concentrate more magnetic flux than central layers of the stack.
This effect was studied by us in evaporated Ag/Co MLs deposited onto Si
substrates. The thickness of Co was 1.3-1.4 nm, i.e. Co layers were continuous. The
thickness of Ag layers was 5.4 –5.8 nm. Then the antiferromagnetic coupling between Co
layers is partly suppressed and the influence of the magnetic flux distribution on GMR
could be observed in superposition with GMR vs. external magnetic field dependence.
Number of periods was only N5 to expose the relative influence of top and bottom parts of
MLs. To make the ML structure symmetrical, an additional Co layer was deposited as first
on the substrate.
Ag/Co MLs were studied by X-ray diffraction(XRD) and X-ray reflectivity (XRR).
The magnetic flux distribution was simulated by an appropriate software tool. GMR
measurements were performed in dynamic conditions in the ac external field at 50 Hz with
increasing swing of the ac field (50 Hz).
The XRD spectra showed well-developed fcc 111 orientation of Ag layers. From
simulations of XRR spectra the effective roughness of ML interfaces 0.4-0.8 nm was
obtained. The GMR signal at RT increased with number of periods up to 4%. The influence
of distribution of the magnetic flux density on GMR was inferred from measurements with
different swing of external magnetic field where the relative increase of GMR beyond
certain value of the field was lower for samples with lower number of periods, i.e. they tend
to saturation of GMR at lower external field intensity.
TF8.6.P
STRUCTURAL CHARACTERIZATION OF RARE EARTH
PARTICLES
L. Ortega1, S. Pokrant2, C. Mayer2
1
Laboratoire de Cristallographie - CNRS, BP 166, F-38042 Grenoble, France
2
Laboratoire Louis Néel - CNRS, BP 166, F-38042 Grenoble, France
It is very well known from semiconductor clusters that delocalised valence electron wave
functions are strongly modified by finite size effects. Since the coupling between the
magnetic moments of the localized f core electrons in rare earth (RE) metals depends on the
valence electron wave functions (RKKY interaction) it can be expected a strong size
dependence of the magnetic properties of rare earth particles. Apart from this size effect,
the magnetic interactions can also be affected by the environment of the particles (the
matrix), since many atoms are located at interfaces (50% for a 1000 atom particle). Our
main goal is to investigate the change of the magnetic order in small rare earth particles in
correlation with structural properties.
For this purpose we have grown self-assembled Tb (0001) 3D nanoparticles and 2D island
by pulsed laser deposition on Nb (110) under strict UHV conditions. In contrast to
experiments performed on isolated particles in molecular beams, the shape, cristallinity and
purity of the Tb particles can be controlled in situ using STM, RHEED and Auger. The
magnetic properties are measured macroscopically and microscopically by Micro-SQUID
measurements on single particles and VSM.
We performed ex-situ X-ray diffraction measurements in our laboratory on a 4 circles
diffractometer using a rotating anode X-ray source. Although the signal to noise ratio is
very low since we work with a very small quantity of Tb (3 monolayers) measurements
show clearly a distorsion of the hexagonal lattice of Tb particles. This change of symmetry
can be related to magnetic properties determined by VSM.
Other structural parameters such as thickness of particles will be reported.