共查询到20条相似文献,搜索用时 15 毫秒
1.
J. Corno M. Galtier D. Renard J.P. Renard F. Trigui 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(2):223-231
We report here on resistance and magnetoresistance (MR) studies of ultrathin Co/Au(111) single sandwiches and bilayers with
perpendicular magnetization. Resistance of the films was measured in situ in ultrahigh vacuum, during depositions and as a function of a perpendicular applied magnetic field. A large MR variation
with the thickness of Au coverage was observed and compared to calculations. The coercive field of the Co films shows a drastic
variation with the Au coverage thickness, which reflects the theoretical anisotropy variation. It was measured as a function
of temperature. For the first time, the effect of interlayer interaction on the resistivity of a Co bilayer during the growth
of Co top layer, is evidenced and compared to calculations. Finally, hysteresis loops of strongly antiferromagnetically coupled
bilayers are investigated.
Received 3 November 1998 and Received in final form 18 January 1999 相似文献
2.
J.L. Bubendorff C. Mény E. Beaurepaire P. Panissod J.P. Bucher 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(4):635-643
The crystallographic structure and morphology of electrodeposited cobalt films on Au(111) is found to be very sensitive on
the electrolyte pH value and on the overpotential applied during deposition. The samples, 2 to 500 nm thick, where characterized
by nuclear magnetic resonance (NMR), atomic force microscopy (AFM) and electron diffraction. The latter technique shows that
the Co films grow in registry with the gold underlayer, reproducing the Au(111) texture. During the first stage of growth
and depending on overpotential and pH value, either continuous hcp Co films or hcp Co islands are formed. Only the latter
growth mode leads to an out of plane magnetization with 100% of remanence. Increasing the thickness, fcc Co becomes the prevailing
phase. Eventually the fcc to hcp ratio saturates at the same value regardless the overpotential. The thickness for which the
equilibrium fcc to hcp ratio is obtained as well as the sample structure and morphology before saturation, depend strongly
on the overpotential value. In any case, the predominance of the fcc Co phase leads to an in plane magnetization of the thick
samples. This study opens up new opportunities of engineering the properties of electrodeposited cobalt films.
Received 29 February 2000 and Received in final form 3 July 2000 相似文献
3.
L. Sheng H.Y. Teng D.Y. Xing 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,10(2):209-213
Using the two-point conductivity formula, we numerically evaluate the giant magnetoresistance (GMR) in magnetic superlattices
with currents in the plane of the layers (CIP), from which the effect of the interfacial roughness and magnetization configuration
on the GMR is studied. With increasing interfacial roughness, the maximal GMR ratio is found to first increase and then decrease,
exhibiting a peak at an optimum strength of interfacial roughness. For systems composed of relatively thick layers, the GMR
is approximately proportional to ,where is the angle between the magnetizations in two successive ferromagnetic layers, but noticeable departures from this dependence
are found when the layers become sufficiently thin.
Received 21 September 1998 and Received in final form 22 December 1998 相似文献
4.
A. Dinia N. Persat S. Colis C. Ulhaq-Bouillet H.A.M. van den Berg 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,18(3):413-419
The effect of the structural quality of the buffer stack on the structural properties, giant magnetoresistance (GMR) and the
quality of the antiferromagnetic coupling has been investigated for Co/Cu/Co sandwiches prepared by DC-magnetron sputtering.
Three kinds of buffers were employed: type A: Cr(6 nm)/Co(0.8 nm)/Cu(10 nm), type B: Fe(6 nm)/Co(0.8 nm)/Cu(10 nm) and type
C: Cr(4 nm)/Fe(3 nm)/Co(0.8 nm)/Cu(10 nm). For B and C type buffers, the antiferromagnetic alignment is very interesting at
zero field with a coupling strength larger than 0.4 erg/cm2 and a GMR signal reaching 5% at room temperature. However, for the A type buffer the antiferromagnetic coupling completely
disappears, while the GMR drops to about 0.8%. X-ray diffraction, atomic force microscopy and transmission electron microscopy
have been performed in order to understand the origin of the observed difference in the magnetic properties. The results show
a strong difference in the average surface roughness, 1.15 nm and 0.35 nm, respectively for the A and C types buffers, and
demonstrate that the quality of the surface of the buffer is the key to optimize both the GMR and the indirect exchange coupling.
Received 11 July 2000 相似文献
5.
C. Meneghini M. Maret V. Parasote M.C. Cadeville J.L. Hazemann R. Cortes S. Colonna 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(3):347-357
Polarized X-ray absorption fine structure (XAFS) measurements at the Co K and Pt L3 edges show that the perpendicular magnetic anisotropy found in epitaxial fcc CoPt3 (111) films stems from the existence of anisotropic local ordering. Such ordering, induced during the codeposition process
and dependent on the growth temperature, is characterized by preferential CoCo pairs in the film plane, balanced by preferential
CoPt pairs out of the plane, resulting from some Co 2D-segregation. Polarized XAFS at the Pt edge reveals similar anisotropic
local ordering in epitaxial hcp Co3Pt (0001) films exhibiting a larger magnetocrystalline anisotropy compared to that of bulk hcp Co. Besides, a polarization
dependence of the Co XANES profile is observed only for the Co3Pt films exhibiting hcp symmetry.
Received: 29 April 1998 / Revised: 27 July 1998 / Accepted: 31 August 1998 相似文献
6.
B. Hillebrands P. Baumgart G. Güntherodt 《Applied Physics A: Materials Science & Processing》1989,49(6):589-598
We give an overview on our experimental and theoretical investigations of Brillouin light scattering in magnetic thin films, layered magnetic structures and superlattices. For epitaxial Fe(1 10) layers on W(1 10) the in-plane and out-of-plane magnetic surface anisotropy constants are determined, and the influence of Pd overlayers on the surface anisotropies is studied. For Fe/Pd superlattices a magnetic polarization of the Pd at the interfaces is established and the interface anisotropy constant is determined. For second order Fe/Pd superlattices, formed by alternating two Fe/Pd bilayers with different repeat periods, the Brillouin spectrum is obtained and compared to calculations. In the case of magnetic/nonmagnetic multilayered structures we investigate theoretically the crossing regime between dipolar and exchange-dominated modes. For small spacer-layer thicknesses, interlayer exchange coupling shifts the spin-wave frequencies of all but the highest-frequency dipolar mode into the exchange-mode regime. In case of all-magnetic multilayered structures, such as Fe/Ni multilayers, a new type of propagating collective excitations arising from coupled exchange modes is predicted. 相似文献
7.
利用扫描隧道显微镜和扫描隧道谱(STM/STS)及单原子操纵,系统研究了单个钴原子(Co) 及其团簇在Rh (111)和Pd (111)两种表面的吸附和自旋电子输运性质. 发现单个Co原子在Rh (111)上有两种不同的稳定吸附位,分别对应于hcp和fcc空位, 他们的高度明显不同,在针尖的操纵下单个Co原子可以在两种吸附位之间相互转化. 在这两种吸附位的单个Co原子的STS谱的费米面附近都存在很显著的峰形结构, 经分析认为Rh (111)表面单个Co原子处于混价区,因此这一峰结构是d轨道共振 和近藤共振共同作用的结果.对于Rh (111)表面上的Co原子二聚体和三聚体, 其费米面附近没有观测到显著的峰,这可能是由于原子间磁交换相互作用 和原子间轨道杂化引起的体系态密度改变所共同导致.与Rh (111)表面不同, 在Pd (111)表面吸附的单个Co原子则表现出均一的高度.并且对于Pd (111)表面所有 单个Co原子及其二聚体和三聚体,在其STS谱的费米面附近均未探测到显著的电子结构, 表明Co原子吸附于Pd (111)表面具有与Rh (111)表面上不同的原子-衬底相互作用与自旋电子输运性质. 相似文献
8.
It is shown in terms of a fully relativistic spin-polarized ab initio-type approach that in Pt/Co/Pt trilayers two types of anisotropic magnetoresistance (AMR) have to be distinguished: an in-plane and an out-of-plane AMR. The obtained results, namely the magnetic field dependence as well as the thickness dependence of both AMR types are in very good agreement with a very recent experimental study, in which the in-plane as well as the out-of-plane AMR was reported for this system. The difference between the two types of AMR is visualized in terms of layer-resolved resistivities. In particular, it is confirmed that the anisotropic interface magnetoresistance (AIMR) introduced in the recent publication mainly originates in the vicinity of the Co/Pt interfaces. 相似文献
9.
U. Pustogowa C. Blaas C. Uiberacker J. Zabloudil P. Weinberger L. Szunyogh C. Sommers 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(4):653-658
The magnetic properties of (ConPdm)r superstructures on Pd(100) and Pd(111) are evaluated using the fully-relativistic spin-polarized screened Korringa-Kohn-Rostoker
method. It is found that only in the case of a Pd(111) substrate such superstructures exhibit perpendicular magnetism, while
on a Pd(100) substrate the magnetization is oriented in-plane. Also investigated is the effect of interdiffusion in repeated
superstructures. By using the inhomogeneous coherent potential approximation (CPA) for layered systems the effect of ordering
into (repeated) superstructures can be described in an ab-initio-like manner. It is found that already small amounts of interdiffusion can be decisive for the actual value of the magnetic
anisotropy energy.
Received 3 November 1999 and Received in final form 18 January 2000 相似文献
10.
L. Piraux S. Dubois A. Fert L. Belliard 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(4):413-420
A theory, based on earlier work by Valet and Fert, is first presented to describe the influence of temperature on the perpendicular
giant magnetoresistance (GMR) in multilayers. Then we present GMR measurements performed at T=77 K and at room temperature on Co/Cu multilayered nanowires with layer thicknesses ranging from a few nm to 1 μm. We use
our model to obtain a good quantitative fit to the experimental results in both the short spin diffusion length limit and
out of this limit. We discuss the temperature dependence of the bulk parameters, the scattering spin asymmetry coefficient
and spin diffusion length in the Co layers.
Received: 25 January 1998 / Accepted: 6 May 1998 相似文献
11.
A. Michel V. Pierron-Bohnes J.P. Jay P. Panissod S. Lefebvre M. Bessière H.E. Fischer G. Van Tendeloo 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):225-239
Epitaxial Co/Mn multilayers (0.75 to 6 nm Co, 0.4 nm Mn layer thickness) have been grown on mica substrates covered by a (0002)
Ru buffer layer. The structural properties of these layers have been studied using X-ray diffraction, nuclear magnetic resonance
(NMR), and high resolution transmission electron microscopy (HRTEM). The Co layers, grown as face centred cubic (fcc), were
found to be stabilised by the very thin Mn layers. Data obtained using X-ray diffraction and NMR were analysed and found to
be in good agreement, while Monte-Carlo simulations were used to interpret the data and calculate the expected diffracted
intensity and NMR spectra. The HRTEM data show that the Mn layers give rise to a large strain contrast extending, in the growth
direction, over a distance which exceeds the thickness of the Mn layers. The superlattices could be described as having an
fcc structure containing randomly located stacking faults with varying densities. The results verify the presence of a dominant,
almost perfect phase of fcc stacking, and of a faulted hcp phase, while the number of defects increases with the Co layer
thickness.
Received 27 October 1999 and Received in final form 29 May 2000 相似文献
12.
Magneto-optic (MO) effects in magnetic multilayers with periodic regions are discussed assuming normal incidence of polarized
waves and polar magnetization (Faraday and polar Kerr effects). From the (4 × 4)-matrix formalism simplified analytical expressions
linear in the off-diagonal permittivity tensor element are obtained with no loss in accuracy. The MO effects are expressed
as weighted sums of contributions from individual layers. Approximate expressions are given for the case when the thickness
of magnetic layers is much smaller than the radiation wavelength. The procedure is illustrated on superlattices consisting
of symmetric sandwiches of ultrathin magnetic and non-magnetic metallic layers.
Partial support from the Grant Agency of Czech Republic # 202/00/0761 is acknowledged. 相似文献
13.
F. J. A. den Broeder D. Kuiper H. C. Donkersloot W. Hoving 《Applied Physics A: Materials Science & Processing》1989,49(5):507-512
Superlattices of [001]fcc Co/Pd with varying Co thicknesses from one to eight atomic layers per modulation period were epitaxially grown on NaCl by vapour deposition in UHV. Transmission electron diffraction indicates lattice coherence between the Co and the Pd layers for Co thicknesses up to six atomic layers. If deposited at a substrate temperatureT
s=50°C, only the superlattices containing Ci-monolayers show perpendicular magnetization. By raisingT
s to 200°C, the perpendicular anisotropy for Co monolayers is increased, and is also observed for Co bilayers. We suggest that this is due tolayer smoothening, which increases Néel's interface anisotropy. For more than 6 atomic layers of Co a loss of coherence is observed atT
s=50°C, accompanied by a structure transformation to hcp Co with a (0001)Co(111)Pd orientation.Non-epitaxial polycrystalline [111]-multilayers have a different anisotropy versus thickness behaviour. For such multilayers the range of Co thicknesses giving perpendicular magnetization is extended from 8 Å up to 12 Å atT
s=200°C. The different behaviour of the single crystal [001] films is caused by a strong volume contribution to the anisotropy, which favours in-plane magnetization, opposing the perpendicular interface anisotropy. This easy-plane term is attributed to magneto-elastic anisotropy due to stretching of the Co layers, via a positive magnetostriction. 相似文献
14.
M. Labrune A. Thiaville 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(1):17-28
Micromagnetic simulations have been performed in order to obtain deeper insight into the domain structures within multilayer
films, as they are expected to differ from those of single films. These 2D calculations have been done in the case of multilayers
exhibiting a moderate perpendicular anisotropy, with no indirect exchange coupling between the magnetic layers, where a “weak
stripe" domain structure develops. First, these results are compared quantitatively to the very detailed experimental data
available in the literature on the (Co/Au)N system. More generally, the nucleation of a stripe pattern in multilayers is discussed as a function of the magnetic parameters
and the number of magnetic layers in the stack. Compared to a single film, two main differences appear in the equilibrium
domain period and the magnetization profiles. The physical origin of these effects is discussed.
Received 12 January 2001 and Received in final form 15 May 2001 相似文献
15.
A.B.C. Patzer C. Chang E. Sedlmayr D. Sülzle 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(1):57-62
We present ab initio thermodynamic properties for seven different geometric isomers of molecular Al2O3 over a wide temperature range. The rigid rotator-harmonic oscillator approximation is used to calculate the partition function
as it is generally applied in thermodynamic studies of polyatomic molecules. The molecular data employed in setting up the
partition functions are taken from the theoretical results of ab initio MP2/6-31G(d) calculations. An analysis of the effects of the various contributions is made. The resulting thermodynamic functions
of Al2O3 are consistent with the JANAF thermochemical data compilation. Some thermochemical implications are discussed.
Received: 9 September 1998 / Received in final form: 2 October 1998 相似文献
16.
A. Milekhin T. Werninghaus D.R.T. Zahn Y. Yanovskii V. Preobrazhenskii B. Semyagin A. Gutakovskii 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(3):295-299
The vibrational spectrum of ultra-thin layer GaSb/AlSb superlattices was investigated in detail by infrared (IR) and Raman
spectroscopies. The effect of confinement of the transverse and longitudinal optical phonons in both types of the layers was
studied. The dispersions of optical phonons of the GaSb and the AlSb obtained from the analysis of the Raman and IR spectra
are in a good accordance with the theoretical data and results of neutron scattering experiments. First- and second-order
Raman spectroscopy indicates the presence of intermixture of atoms at the interfaces in the GaSb/AlSb superlattices.
Received: 11 May 1998 / Accepted: 21 July 1998 相似文献
17.
W. Kuch 《Applied Physics A: Materials Science & Processing》2003,76(5):665-671
Photoelectron emission microscopy in connection with magnetic circular dichroism in soft X-ray absorption can be used for
the microscopic imaging of magnetic domains in layered thin film structures consisting of several magnetic layers. Due to
the element-selectivity of the method, the different magnetic layers in such a structure can be imaged separately, provided
that they contain different elements. This has been applied for the investigation of Co/Cu/Ni trilayers, epitaxially grown
on Cu (001). The magnetic coupling between the Co and Ni layers can be directly visualized from comparing layer-resolved magnetic
domain images of both layers. As a consequence of the competition between the anisotropy energies of the two magnetic layers
and the magnetic coupling energy, spin-reorientation transitions between collinear and non-collinear magnetic configurations
are observed. Apart from this globally observable magnetic interlayer coupling a micromagnetic coupling mechanism is also
evident from the layer-resolved domain images. It is caused by magnetostatic interaction of local stray fields from domain
walls.
Received: 22 August 2002 / Accepted: 2 October 2002 / Published online: 5 February 2003
RID="*"
ID="*"Corresponding author. Fax: +49-345/5511-223, E-mail: kuch@mpi-halle.de 相似文献
18.
A. Ślebarski A. Jezierski M. Neumann S. Plogmann 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(4):519-523
The electronic structure of the Co2-xZrSn Heusler alloys has been studied by X-ray photoelectron spectroscopy (XPS). XPS valence band spectra can be compared with
ab initio electronic structure calculations using the linearized muffin-tin orbital (LMTO) method. The calculated magnetic moments
per Co atom agree well with the moments obtained from experiment. The LMTO calculations also show the energy shifts of the
Co, Zr and Sn valence electron states towards the Fermi level when the concentration of vacancies increases in these alloys.
Received 9 March 1999 and Received in final form 6 May 1999 相似文献
19.
M.G. Kozlov S.G. Porsev 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(1):59-63
The results of ab initio calculation of energies, hyperfine structure constants and static polarizabilities for several low-lying levels of barium
are reported. The effective Hamiltonian for the valence electrons has been constructed in the frame of CI+MBPT method and solutions of many electron equation were found. Using the wave functions obtained the hyperfine structure constants and static polarizabilities were calculated.
Received: 22 June 1998 / Revised: 2 September 1998 / Accepted: 15 September
1998 相似文献
20.
In the asymptotic limit, the interlayer exchange coupling decays as D-2, where D is the spacer thickness. A systematic procedure for calculating the preasymptotic corrections, i.e., the terms of order D-n with ,is presented. The temperature dependence of the preasymptotic corrections is calculated. The results are used to discuss
the preasymptotic corrections for the Co/Cu/Co(001) system.
Received 7 January 1999 相似文献