Magnetic Multilayers As Seen by Photons
and Neutrons
6-9 December, 2001
Budapest, Hungary
Abstract
Booklet
Magnetic and Magnetotransport Properties of Fe-Ag Multilayers
J. Balogh, D. Kaptás, L. F. Kiss, T. Pusztai, I.
Vincze
Research Institute
for Solid State Physics and Optics Budapest, H-1525 P.O.B. 49 Hungary
M. Csontos, A. Halbritter, I. Kézsmárki, G.
Mihály
Budapest University of Technology and Economics, Budafoki út 8. Budapest, Hungary
Fe-Ag multilayers were prepared by vacuum evaporation with two electron guns. The magnetic properties were examined by Mössbauer spectroscopy and SQUID magnetometry. Below 1 nm thickncess the Fe layers are discontinuous and the samples show giant magnetoresistance similar to that observed in granular alloys prepared with co-deposition methods. The large resistance change observed up to 12 T applied magnetic field is attributed to spin dependent electron scattering on superparamagnetic grains embeded in a nonmagnetic matrix. The superparamagnetic blocking could be observed in the temperature dependence of both the bulk magnetisation and the local hyperfine fields. The average grain size, as indicated by the blocking temperature, and the magnetoresistance depend sensitively on the nominal layer thickness. Our results indicate that the optimum concentration of the magnetic atoms to observe large magnetoresistance is not universal.
Soft-X rays Magnetic Scattering on striped and patterned films
K. Chesnel, M. Belakhovsky, S. Landis, A. Marty, B.
Gilles, B. Rodmacq
CEA Grenoble
E. Dudzik
HMI Berlin
S.P. Collins, G. van der Laan
SRS Daresbury
S.S. Dhesi
ESRF
In the frame of Nanomagnetism, we focus on systems relevant as model or application to data storage at ultrahigh densities. Soft x-ray resonant magnetic scattering (SXRMS) at ESRF is used to explore magnetic nanodomains in :
- epitaxial FePd alloys with antiferromagnetic stripes
- Co/Pt multilayers, sputter deposited onto Si nanolines
These two systems present a lateral periodicity, that leads to purely magnetic satellites in off-specular scattering at the L2,3 resonance of the 3d metal.
In the case of FePd, we have in particular :
- obtained (qx, qz) maps that show the sensitivity to the magnetic profile in thin FePd films[1]
- observed closure domains [2]
- studied the influence of in situ H-field on the nanodomain topology [3]
- recorded magnetic speckles in reflection geometry, a new way for domain dynamics.
In the case of Co/Pt nanolines on etched Si, main results deal with :
- the sensibility of AF magnetic satellites to the pattern geometry (e.g. interline separation)
- the study of the magnetic reversal process, by following the whole hysteresis loop [4]
Finally, some perspectives will be given on the potential of SXMRS for magnetic film studies.
References
[1] Dudzik E. et al, Phys. Rev. B 62
(2000) 5779
[2] Dürr H.A. et
al, Science 284 (1999) 2166
[3] Marty A. et al, J. Appl. Phys. 87 (2000) 5472
[4] Chesnel K. et al, submitted to Phys. Rev. B
Common approach to polarized neutron - and synchrotron
Mössbauer reflectometry
L. Deák, L. Bottyán, D. L. Nagy
KFKI Research Institute for
Particle and Nuclear Physics Budapest, H-1525 P.O.B. 49 Hungary
H. Spiering
Institut f. Anorganische
Chemie und Analytische Chemie, Johannes Gutenberg Universit\"{a}t, Mainz,
Germany
Spin Polarized Neutron Reflectometry
(SPNR) is a powerful tool of studying magnetic multilayers (MMLs). The layer
magnetisations of a MML are not necessarily parallel or antiparallel to the
neutron spins, a fact resulting in spin flip scattering processes. This should
be properly accounted for when SPNR data are evaluated. Important examples of
this case are antiferromagnetically coupled multilayers in external magnetic
field.
Close to the nuclear resonant transition
energies, the hyperfine interactions affect the photon's scattering amplitude
in a similar way as the atomic magnetic moments influ\-ence the scattering
amplitude of neutrons. This fact is the key to Mossbauer reflectometry. With
the advent of high-brilliance synchrotron radiation sources, Synchrotron
Mossbauer Reflectometry (SMR) became a method of studying MMLs with an
efficiency which is competitive with that of SPNR. Admittedly, SMR is
restricted to MMLs containing a resonant isotope, typically 57Fe. A fast
evaluation algorithm of specular SMR and nonresonant specular x-ray
reflectivity data based on an anisotropic optical model of nuclear resonant
photon scattering has recently been developed.
We show that the same formalism can also
be used to evaluate specular SPNR data in the most general cases and with no
numerical difficulties. The anisotropic optical algorithm was generalized to
take into account the guiding field effect. We developed a computer program
that can be used for simultaneous
fitting of data of different kinds of reflectometric methods, such as SMR, SPNR
and x-ray reflectometry.
Conservation of uniaxial symmetry in Fe/Ag multilayers grown on stepped Ag(001)
B. Degroote, J. Meersschaut, J. Dekoster, B.
Croonenborghs and
G. Langouche
Instituut voor Kern- en Stralingsfysica, Katholieke Universiteit Leuven,
Belgium
M. Major
KFKI Research Institute for
Particle and Nuclear Physics, Budapest, Hungary.
Abstract
We obtained a stepped Ag(001) surface by
growing a 100 nm thick Ag film on a polished MgO(001) crystal with a miscut of
1.8º in the [10] direction. With Scanning Tunneling
Microscopy we observe terraces of (7 ± 3) nm wide separated by mono-atomic
steps that are straight over at least 200 nm in the [110] direction. The
interface structure of Fe/Ag multilayers grown at room temperature on vicinal
Ag(001) is investigated for 15 monolayers (ML) of Fe and a Ag thickness ranging
from 2 to 10 ML. During Fe growth the step structure disappears at the surface
of the film. When Ag is deposited on top, steps already reappear at 2 ML. For
increased Ag thickness, the steps straighten out and the roughness on terraces
decreases. At 8 ML of Ag the step length and surface roughness is comparable to
the uncovered Ag surface. However, on larger terraces, Ag islands are observed.
In addition we compare the direction of magnetization with respect to the
surface normal of an [Fe(15ML)/Ag(4ML)]16 multilayer grown on
vicinal and flat Ag(001). For the vicinal substrate, at room temperature, we
observe in-plane magnetization whereas for the flat substrate the magnetization
is 29º out-of-plane. The results are discussed with respect to step anisotropy
and step-related symmetry.
Probing the Magnetisation Reversal and Morphology in Transition Metal Multilayers
T.P.A. Hase,
J.D.R. Buchanan and B.K. Tanner
Department of Physics,
University of Durham, Durham, DH1 3LE
C.H. Marrows M.
Perez and B.J. Hickey
Department of Physics and
Astronomy, University of Leeds, Leeds, LS2 9JT
S. Foster, R.
Dalgliesh and S. Langridge
ISIS, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX
Grazing incidence x-ray scattering is a proven technique for the elucidation of structural interface morphologies in transition metal multilayers. An equally important parameter is the magnetisation profile and morphology at the interfaces. We present polarised neutron reflectivity and resonant magnetic x-ray data from the same, anti-ferromagnetically coupled Fe/Cr, Co/Cu and Co/Ru multilayers. Both experimental methods probe the magnetisation direction and amplitude. We compare both the specular and diffuse scatter, recorded over the same out-of-plane momentum transfer range, using both experimental techniques. Models based on domain disorder, magnetic ripple and interface roughness are contrasted, and the sensitivity of the experimental techniques to each are discussed. By following the intensity variations of specular peaks, the coupled rotations of the AF layers are followed in real time. This reveals substantial magnetic viscosity occurring over timescales of minutes, being field amplitude and direction sensitive.
Unlike the neutron data, no specular AF peak is observed in the same Fe/Cr and Co/Ru systems when these samples are studied using resonant x-ray scattering. A clear diffuse peak is observed both at the structural and half-order magnetic Bragg peaks. By assuming a simple height-height correlation function we have been able to obtain separately in-plane correlation lengths and roughness for the magnetic and charge roughness morphology.
Epitaxial Fe/Si/Fe(001) - Structure and Magnetism of a Unique System
Jürgen Kohlhepp
Department of Applied
Physics, Eindhoven University of Technology,
P.O.Box 513, 5600MB Eindhoven, The Netherlands
In the search for novel magnetoelectronic devices mainly all-metallic systems like e.g. Co/Cu have been investigated in great detail in the past. Nowadays metal/semiconductor and metal/insulator combinations draw more and more attention as possible new materials for spin-electronics.
Fe/Si/Fe sandwich systems epitaxially grown on atomically clean Ge(001)or Ag(001) substrates by Molecular Beam Epitaxy (MBE) have been studied extensively by a number of both in-situ and ex-situ methods, including LEED, XPS, AES, STM, Mössbauer spectroscopy, x-ray reflectometry, MOKE and polarized neutron reflectometry. These systems feature a number of both structural as well as magnetic interesting and unique properties: A bcc-like (001) structure is maintained throughout the layers after the recrystallization of the spacer into a metastable iron silicide phase with a CsCl (B2) structure by Fe/Si interdiffusion during growth. Both very stong bilinear and biquadratic magnetic interlayer exchange coupling are observed with a rather exceptional behaviour, their strengths decay exponentially with the nominal Si spacer layer thickness, in contrast to the usually observed oscillatory behaviour. Furthermore, the biquadratic exchange shows a strong temperature dependence, whereas the bilinear coupling is almost temperature independent. While the bilinear coupling is an intrinsic effect caused by distinct density of states features of the metallic iron-silicide spacer, the biquadratic exchange is extrinsic in nature and can be understood by so-called ”loose spins” in the spacer layer.
Spin-resolved polarized and unpolarized neutron off-specular scattering for magnetic multilayer studies
V.Lauter-Pasyuk1,2,
H.J.Lauter3, B.Toperverg4,5, L. Romashev6, V.
Ustinov6
1TU München, D-85747
Garching, Germany
2JINR, 141980 Dubna, Russia
3ILL, B.P.156, F-38042,
Grenoble, France
4PNPI, 188450, Gatchina, Russia
5IFF, D-52425 Jülich, Germany
6Institute of Metal Physics,
62019 Ekterinburg, Russia
The non-collinear coupling of magnetic moments in a Fe-Cr multilayer stack is laterally constrained to domains seen by off-specular spin-flip half order Bragg-sheet scattering. The magnetic field dependence of the coupling angle, which scales with the GMR effect, is directly obtained through the cut-off of the off-specular Bragg-sheet scattering at the neutron spin-dependent critical angles.
Interface roughness manifests in off-specular scattering through full order Bragg-peaks. It is independent on a magnetic field and thus does not influence the magnetic field dependence of the GMR effect.
We report also on a new possibility using unpolarized neutron scattering for the investigation of magnetic structure in exchange coupled magnetic multilayers. Strong anomalies in the off-specular scattering are determined by the spin-flip process originating from magnetic structure in the multilayer. This spin-flip selective process enables to use unpolarized neutrons.
A complete 2-dimensional data analysis of specular and off-specular scattering has been employed to verify the details of the layer magnetic structure and the in-plane domain distribution in Fe/Cr multilayers, a typical system showing the GMR-effect.
2-dimensional model calculations performed in the DWBA with supermatrix formalism allows for a detailed comparison of the data in particular in regions with interference from spin-dependent critical angle scattering with off-specular scattering of the multilayer structure. A very good agreement of the 2-dimensional model calculation with the data is obtained.
The approach to spin resolution in experiments with grazing-incidence
neutrons
JÁNOS MAJOR
Max-Planck-Institut für
Metallforschung, Stuttgart, Germany
Spin-resolved
specular and diffuse scattering of grazing incidence neutrons from a flat
sample surface may provide us with important details on the magnetic and the chemical
structure of magnetic multilayer samples, such as the magnitude, orientation,
and homogeneity of the local magnetic fields in the individual layers or the chemical
and magnetic roughness of the interfaces. Since the distribution of the
practical scattering angles of the neutrons are broader then the acceptance
angle for the standard supermirror neutron spin analizer, the application of
wide-angle neutron spin filters are desirable. In the present talk the usage
and performance of polarized 3He gas neutron spin analyser will be
presented as used at the EVA reflectometer at ILL.
The detection of the neutrons which are diffusely scattered
in the sample plane normal to the incoming neutron beam, can be made very
effective by the combination of the neutron spin echo with inclined magnetic
field borders in neutron reflectometry set-up (SERGIS, spin-echo resolved
grazing incidence neutron scattering). In the talk results obtained from the
first SERGIS experiments will also be shown as well as the possibility will be
discussed, how can this method be applied for the study of magnetic systems.
Off-specular synchrotron Mössbauer reflectometry in studying domain structure of antiferromagnetic multilayers
D.L. Nagy,
L. Bottyán, L. Deák, M. Major, E. Szilágyi
KFKI Research Institute for
Particle and Nuclear Physics,
P.O.B. 49, H–1525 Budapest, Hungary
B. Degroote, J. Dekoster,
J. Meersschaut, A. Vantomme
K.U. Leuven, Instituut voor Kern- en Stralingsfysica, Celestijnenlaan
200 D, B‑3001 Leuven, Belgium
O. Leupold, R. Rüffer
European Synchrotron Radiation Facility, BP 220,
F–38043 Grenoble, France
J. Swerts, K.
Temst
K.U. Leuven, Laboratorium voor Vaste-Stoffysica en Magnetisme,
Celestijnenlaan 200 D, B‑3001 Leuven, Belgium
Specular reflectometric methods have been known to probe the plane-perpendicular component qz of the scattering vector in a stratified system thereby revealing its (possibly periodic) depth profile. The off-specular (diffuse) reflectivity probes the component qx of the scattering vector and reveals the in-plane correlation length of the scattering amplitude. We used off-specular synchrotron Mössbauer reflectometry (SMR) to study the in-plane correlation length of the magnetisation direction in an antiferromagnetically (AF) coupled multilayer. The SMR qx-scan width at the AF Bragg-peak (i.e. at fixed qz) is inversely proportional to the size of the AF domains. Using off-specular SMR a surprising magnetic-field-history dependence of the AF-domain size in a Fe/Cr coupled superlattice with fourfold magnetocrystalline anisotropy was revealed.
Sub-micrometer-size primary domains were formed as the external field was decreased from well above the apparent saturation field of the AF-coupled Fe layers of about 0.9 T. On decreasing the field to zero, a spontaneous, coercivity-limited growth of the domains ('ripening') resulted in domains of a few micrometer size. When a small field of about 14 mT along the layer magnetizations induced a spin-flop transition, a secondary domain state with majority large and minority small domains was created ('coarsening'). The large domains were at least ten times bigger than the small ones. The primary small-domain state only retained when a field of about 1.3 T (i.e. well above the apparent saturation field) had been applied again.
The AF-domain size distribution was found to reproducibly depend on the magnetic field history. The condition for domain coarsening in AF multilayers is the equilibrium of the external field energy with the magnetocrystalline anisotropy energy rather than with the domain wall energy. The spin-flop-induced domain coarsening is an explosion-like growths of the domain size, not connected with long-range domain-wall motion and, consequently, not limited by coercivity.
The observed apparent 'supersaturation memory effect' is probably related to the magnetism of the Cr spacer layers.
Neutron standing waves for multilayer applications
Yu. V. Nikitenko
Frank Laboratory of Neutron Physics Joint Institute for Nuclear Research, Dubna, Russia
Possibilities
of creating a field of neutron standing waves in a layered nanostructure for
the purposes of investigation of the
properties of the structure itself are discussed. The status of investigations
of such neutron wave fields is formulated. The results of investigations in the
regimes of neutron standing waves and enhanced neutron standing waves with a
specified neutron spin state using different
measurement channels are presented.
FeAu
multilayers seen by MOKE and CEMS
T.Ślęzak1,
D. Wilgocka-Ślęzak1, B.Croonenborghs2, M.Rots2,
W.Karaś1, K. Krop1,
N. Spiridis3,
J.Korecki1,3
1Faculty of Physics and
Nuclear Techniques, University of Mining and Metallurgy, Al. Mickiewicza 30, 30-059
Kraków, Poland.
2K.U. Leuven, Instituut voor
Kern- en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
3Institute of Catalysis and
Surface Chemistry Polish Academy of Sciences, ul. Niezapominajek
8, 30-239 Kraków, Poland
Epitaxial metallic multilayers allow fabrication of the artificial phases having intriguing magnetic properties. Monoatomic FeAu superlattices are well known example possessing perpendicular magnetic anisotropy, large magnetic moments combined with a high Curie temperature . The MBE layer by layer growth stabilizes L10 –type ordered phase that not exist in Fe-Au phase diagram. In the present work the coupling behavior will be demonstrated in the two types of multilayers. First one composed of FeAu monoatomic superlattices as building blocks (spaced with Au nonmagnetic spacers) and the second one, more complicated, consisting of FeAu superlattices separated by the Au spacer layer from the ultra-thin pure Fe films. The first mentioned configuration leads to the artificial antiferromagnets formation with an out-of-plane easy magnetization axis. The second one allows stabilization of the modern non-collinear magnetic states arising from the subtle competition between magnetic anisotropy and the interlayer exchange coupling in the multilayers with sub-layers having alternatively out-of-plane and in-plane magnetic anisotropy. The magnetic properties of the MBE grown samples were investigated with polar and longnitudinal MOKE and CEMS. The CIP magnetoresistance was measured with conventional four-terminal method at temperatures between 5K and RT.
Kerr-Microscopy on Magnetic Multilayers
R. Schaefer
IFW-Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany
Magnetooptical Kerr microscopy, enhanced by image processing, is known for being a very versatile method of domain imaging for all kinds of magnetic materials. Samples of arbitrary geometry can quickly be investigated at ambient conditions with magnifications that can vary over several orders of magnitude. Arbitrary magnetic fields can be applied, allowing the study of magnetization processes, and observations at high or low temperature are possible in a heating stage and optical cryostat, respectively. In magnetic multilayers, an information depth of about 20 nm allows the simultaneous imaging of domains in all layers within that thickness range. Under favorable conditions, layers may also be selectively imaged by using a phase shifting compensator.
In this presentation the possibilities of Kerr microscopy for the analysis of the magnetic microstructure in magnetic multilayers will be reviewed by presenting observations on (i) sandwiches and multilayers with ferromagnetic, antiferromagnetic and biquadratic coupling, (ii) weakly coupled and virtually uncoupled multilayers, (iii) spin-valve systems, and (iv) exchange-biased antiferromagnet/ferromagnet bilayers and soft-/hard ferromagnetic bilayers.
Structural and magnetic properties of periodic dot lattices studied by off-specular x-ray and neutron reflectivity
K. Temst, M.J.
Van Bael, J. Swerts, C. Van Haesendonck, Y. Bruynseraede
Laboratorium voor Vaste-Stoffysica en Magnetisme, K.U. Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium
H. Fritzsche
BENSC, Hahn-Meitner-Institut, Glienicker
Strasse 100, D-14109 Berlin, Germany
We have studied the structural and magnetic properties of small magnetic polycrystalline Co islands, which are prepared by a combination of electron beam lithography and molecular beam epitaxy on SiO2 substrates, with the aim of elucidating the interplay between shape and physical properties. The islands have a rectangular shape with dimensions of the order of 300 nm up to a few micron. They are placed in a square array with a period of a few micron; an area of several cm² is patterned.
Specular and off-specular x-ray reflectivity measurements have been carried out to study the internal structure of the dots, as well as the in-plane periodicity of the dot array. Magnetic force microscopy measurements reveal the domain structure in the dots and provide the possibility to chart the transition from single-domain to multidomain structures by varying the aspect ratio of the dots.
Finally, off-specular polarized neutron reflectivity experiments were carried out to study the magnetization reversal in the dots. By measuring the intensity of the resonant satellite peak in the off-specular reflectivity as a function of applied field, and by analyzing the spin-flip and non-spin-flip reflectivity, a vectorial determination of the in-plane magnetization in the dot can be made.
This
work is supported by the Belgian Fund for Scientific Research – Flanders (FWO),
the Flemish Concerted Action (GOA), the Belgian Inter-University Attraction
Poles (IUAP) research programs, and by the European Commission under the Human
Potential Program (HPRI-1999-CT00020).
KT and MJVB are post-doctoral research fellows of the FWO.
Studies on Rare-Earth/Iron and Actinide/Iron Multilayers
M.F. Thomas,
G.S. Case, J. Bland, A. Herring, W.G. Stirling, S. Tixier1, P. Boni1,
R.C.C. Ward2, M.R. Wells2 S. Langridge3
Department of Physics,
University of Liverpool, Liverpool L69 7ZE, UK
1Paul Scherrer Institute,
Villigen, Switzerland
2Clarendon Laboratory, University
of Oxford,Oxford OX1 3PU,UK
3ISIS, Rutherford-Appleton Laboratory, Chilton, Oxfordshire
OX11 QX, UK
Multilayers of Ce/Fe and U/Fe were fabricated by sputtering and studied by a variety of techniques including x-ray reflectivity, x-ray diffraction, Mossbauer spectroscopy, magnetization and polarized neutron reflectivity.
Mössbauer spectra showed the iron layers to be composed of crystalline and amorphous components. Strong interfacial magnetic anisotropy was observed in Ce/Fe (and in Ce/FeCoV) multilayers that resulted in iron layers with large perpendicular moment components for iron layer thicknesses less than ~17Å. In studying the mechanism for the interfacial anisotropy, polarised neutron reflectivity results measured the moments on the iron layers but did not detect moments on the intervening Ce or U layers.
Dependence of spin density wave polarization, on the growing
temperature of Fe/Cr trilayers
Van Eek S.M.,
Aernout D., Slezak T., Meerschaut J., Cronenbourghs B., Wilgocka-Slezak D., Rots
M.
Institut
voor Kern en Stralingsfysica, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
Previous investigations by Dekoster et al. [1] found that the IC (Interlayer Coupling) between Fe layers in Fe/Cr/Fe depends strongly on the growth temperature of the trilayer and the magnetic properties of the Cr spacer layer. This effect was found not to be a result of strain and roughness at the interfaces.
Trilayers Fe(40Å)/ Cr(80 Å) /Fe(40 Å) were grown with MBE on a MgO(001) substrate at different temperatures. 111In probes were implanted inside the trilayer to measure PAC spectra. The structure and composition of the samples was monitored with RHEED and RBS. Additionally the interlayer exchange coupling was analysed using a VSM (vibrating sample magnetometer).
The VSM magnetization curves measured as a function of temperature (10K to 300K) for the Fe/Cr trilayer grown at RT show no coupling. This behaviour is interpreted as the influence of the Cr magnetic ordering. PAC measurements show the presence of a longitudinal SDW in the Cr layer at T=77K to 290K, in correlation with the coupling behaviour.
Results on trilayers grown at higher temperatures will be presented and compared with previous results on Fe/Cr multilayers.
References
[1] J. Dekoster,
J. Meerschaut, S. Hogg, S. Mangin, E. Nordstrom, A. Vantomme. and G. Langouche
JMMM 198-199(1999) pp303-305
Magnetic heterostructures as seen by x-rays and neutrons
Hartmut Zabel
Institut für
Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum
D 44780 Bochum, Germany
The magnetism of ultrathin magnetic heterostructures is one of the most active fields in the area of condensed matter and materials science research. This interest is driven by their use in an increasing number of applications as spin- and magneto-electronic devices. In addition, there is a genuine interest in exploring scaling and proximity effects as one of the physical dimensions is reduced. Traditionally neutron scattering has played a dominant role for the determination of spin structures, phase transitions, and magnetic excitations in bulk materials. Today, its potential for the investigation of thin magnetic films has to be redefined. In the field of thin film magnetism, polarized neutron reflectivity (PNR) at small wave vectors can provide precise information on the magnetic field distribution normal to the film plane and on layer resolved magnetisation vectors. Therefore, neutron scattering remains a unique method for unravelling the magnetisation in thin films and superlattices independent of their thickness and depth below the surface. In addition, x-ray resonant magnetic scattering has gained in recent years much momentum. Similar to PNR, XRMS is sensitive to the layer magnetisation and to the magnetic roughness, while adding element specificity. In this lecture recent examples from studies of magnetic heterostructures via magnetic neutron and x-ray scattering will be discussed and compared. The main emphasis will be on exchange coupled Ho/Y superlattices and on Co/CoO exchange biased systems.
Study of biquadratic coupling in Fe/Cr multilayers
D. Aernout, S.M. Van
Eek, T.Slezak, D. Wilgocka, B. Croonenborghs, D. Knops,
J. Meersschaut, M. Rots
Instituut voor Kern- en Stralingsfysica,
Celestijnenlaan 200D, B-3001 Leuven, België
Previous
investigations on Fe/Cr trilayers grown at T>423K showed that the difference
in the coupling strength is dependent on the growth temperature of the system
and is correlated to the strain in the Cr layer [1]. Fe(3nm)/Cr(6nm)/Fe(3nm) trilayers were grown at different
temperatures (295K, 400K and 575K).
Magnetization curves were measured by vibrating sample magnetometry and
homogeneity of the sample was checked with MOKE. Strain was measured with Rutherford backscattering spectroscopy
in channeling geometry along the (111)-axis for the Fe and Cr layers
separately. X-ray reflectivity
measurements determine the total thickness and roughness present in the Fe/Cr
trilayer.
[1] J.Dekoster et al., J. Magn. Magn. Mater. 198-199,
303 (1999)