共查询到20条相似文献,搜索用时 10 毫秒
1.
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
2.
H.A. Dürr M. Münzenberg W. Felsch S.S. Dhesi 《Applied Physics A: Materials Science & Processing》2001,73(6):693-696
The magnetic domain configurations of Fe 3d spins in Fe/CeH2 multilayers were measured by soft X-ray resonant magnetic scattering. The interface region could be probed by setting up
X-ray standing waves due to the multilayer periodicity. By resolving first- and second-order magnetic scattering contributions,
we show that the latter probe directly the magneto-crystalline anisotropy which is dominated by the Fe interface layers causing
a spin reorientation transition when the temperature is lowered.
Received: 30 May 2001 / Accepted: 4 July 2001 / Published online: 5 October 2001 相似文献
3.
We observe ferromagnetic exchange-coupling to be induced between thin Fe layers separated by an insulating SiO barrier upon light irradiation. Coupling can reversibly be switched on with photons of energies less than the bandgap of SiO. We conclude that charge carriers in localized states within the bandgap mediate the observed exchange-coupling. We furthermore report that the exchange-coupling can also be turned off by irradiation with light of higher intensity. 相似文献
4.
F. Rose O. Schulte P. Schaaf W. Lohstroh W. Felsch 《Applied Physics A: Materials Science & Processing》1996,63(2):183-190
The structural and magnetic properties of La/Fe multilayers were investigated by X-ray diffraction, RHEED, magnetometry and57Fe Mössbauer spectroscopy. Comparison is made with previous results obtained for Ce/Fe multilayers. Remarkably sharp interfaces are found, with roughness between 2 and 2.5 Å. The magnetic interface in the Fe sublayers resulting from the distribution of magnetic hyperfine fields distinctly exceeds the extension of the structural interface and points to a magnetic proximity effect. This is discussed in relation to a strong 3d-5d hybridization recently found in measurements of magnetic circular X-ray dichroism. Both the structural and magnetic La/Fe interface is less extended than the interface in Ce/Fe multilayers. Below a thickness of about 25 Å, the individual Fe layers grow in an amorphous structure on the La layers. In this case, Curie temperatures are below 200 K and the Fe-layer saturation magnetization is reduced up to 50%, and there is evidence of a non-collinear spin structure. It is argued that this mainly reflects the properties of pure amorphous Fe. 相似文献
5.
Some interesting behaviors observed in nanostructured magnetic multilayers with alloy spacers 总被引:1,自引:0,他引:1
Y.J. Wang 《Applied Physics A: Materials Science & Processing》1999,68(2):231-238
Received: 27 March 1998 相似文献
6.
A.A. Stashkevich Y. Roussigné N.I. Novitskii A.V. Zayats G. Chaboussant L.V. Lutsev M.P. Kostylev 《Journal of magnetism and magnetic materials》2009,321(7):876-879
Behaviour of magnetic excitations in the Damon-Eshbach (DE) and backward volume (BV) geometries in nano-composite (SiO2)100−xCox (50% at<x<80% at) films has been studied by Brillouin light scattering (BLS). It has been shown that it is the structure of Stokes/anti-Stokes BLS lines in the DE geometry that allows reliable identification of dipole-exchange spin waves (SW) and numerical estimation of the value of the effective exchange constant Aeff of a super-ferromagnetic nano-granular sample (x=80% at). 相似文献
7.
Thin films of the metal organic molecule bis(4-cyano-2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II) (or Cu(CNdpm)2), (C24H36N2O4Cu, Cu(II)), deposited on ferromagnetic Co(111) at 40 K, exhibit a finite electron spin polarization. The spin polarization magnitude and sign for Cu(CNdpm)2 deposited on Co(111) is coverage dependent, but deviates from the mean field expectations for a simple paramagnet on a ferromagnetic substrate. The spin asymmetry is seen to favor select molecular orbitals, consistent with the predicted single molecule density of states. The overlayer polarization observed indicates a strong influence of the ferromagnetic Co(111) substrate and some extra-molecular magnetic coupling. 相似文献
8.
The spectrum of magnetostatic surface spin waves of a stack of magnetic and nonmagnetic layers is investigated theoretically. The calculation treats a very general case: each layer is allowed to be of different thickness, magnetization and magnetocrystalline anisotropy. Some interesting spezial cases are discussed in detail. 相似文献
9.
W. P. Zhou G. H. Yun X. X. Liang 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(1):37-42
The eigenproblems of spin waves in a heterogeneous ferromagnetic bilayer
system with periodic boundary conditions are solved using the
interface-rescaling approach. Brillouin zone mapping and the eigenmodes of
the system are investigated. We find three types of spin waves may exist in
the system: the bulk mode, the interface mode, and the perfect confined
mode. The fine structure of the energy band in the heterogeneous bilayer
system is first given for the whole two-dimensional Brillouin zone.
Conditions for the existence of the interface mode are discussed. Finally,
we analyze the resonant-confined spin waves in bulk modes and their
oscillating behavior. 相似文献
10.
Nd–Fe–B-type hard phase single layer films and nanocomposite Nd28Fe66B6/Fe50Co50 multilayer films with Mo underlayers and overlayers have been fabricated on Si substrates by rf sputtering. The hysteresis loops of all films indicated simple single loops for fixed Nd–Fe–B layer thickness (10 nm) and different FeCo layer thickness (dFeCo=1–50 nm). The remanence of these films is found to increase with increasing dFeCo and the coercivity decrease with increasing dFeCo. It is shown that high remanence is achieved in the nanocomposite multilayer films consisting of the hard magnetic Nd–Fe–B-type phase and soft magnetic phase FeCo with 20 nm?dFeCo?3 nm. The sample of maximum energy product is 27 MG Oe for dFeCo=5 nm at room temperature. The enhancement of the remanence and energy products in nanocomposite multilayer films is attributed to the exchange coupling between the magnetically soft and hard phases. 相似文献
11.
N. Jaouen J.M. Tonnerre D. Raoux L. Ortega E. Bontempi M. Münzenberg W. Felsch M. Suzuki H. Maruyama H.A. Dürr E. Dudzik G. van der Laan 《Applied Physics A: Materials Science & Processing》2001,72(6):711-715
The element and electronic shell specificities of X-ray resonant magnetic scattering have been used to investigate the magnetization
of Ce 5d and Fe 3d states in [CeH2(19.6 ?)/Fe(25.4 ?)]*38 a multilayer. We show that the measurement of the magnetic contribution to the intensities reflected
at low angles at the Ce L2 and Fe L2,3 edges allows us to investigate the profile of the Ce 5d and Fe 3d magnetic polarization. The Fe 3d polarization is found
to be uniform across the Fe layer and the Ce 5d polarization appears to be restricted close to the interface with Fe.
Received: 22 May 2001 / Accepted: 4 July 2001 / Published online: 5 October 2001 相似文献
12.
The magnon energy bands are studied for a four-layer ferromagnetic superlattice, with regard to the effects of the competition between the anisotropy and the spin quantum number. A special attention is also paid on the effects of the symmetry of the system. It is found that three modulated energy gaps exist in the magnon energy band along Kx direction perpendicular to the superlattice plane. The magnetic anisotropy affects significantly the magnon energy gaps. The zero energy gap Δω23 correlates with the conditions between anisotropy constants, D1+D3=D2+D4 and D1=D3 (or D2=D4), while the disappearance of the magnon energy gaps Δω12 and Δω34 corresponds to a translational symmetry of x-direction in a unit cell. When the parameters of the system deviate from these conditions, the energy gaps Δω12, Δω23 and Δω34 become larger. There is a competition effect of the anisotropy and the spin quantum number on the magnon energy gaps Δω12 and Δω23. When the symmetry of the system is higher, the competition can achieve a balance to cause the zero energy gap. 相似文献
13.
Y.C. Tao X.F. Jiang J. Wang D.Y. Xing 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(4):463-469
An extended tunneling Hamiltonian method is proposed to study the temperature-dependent tunneling magnetoresistance (TMR)
in doped magnetic tunnel junctions. It is found that for nonmagnetic dopants (Si), impurity-assisted tunneling is mainly elastic,
giving rise to a weak spin polarization, thereby reduces the overall TMR, while for magnetic ions (Ni), the collective excitation
of local spins in δ-doped magnetic layer contributes to the severe drop of TMR and the behavior of the variation of TMR with
temperature different from that for Si-doping. The theoretical results can reproduce the main characteristic features of experiments.
Received 13 January 2002 / Received in final form 30 November 2002 Published online 6 March 2003
RID="a"
ID="a"e-mail: yctao12@163.com 相似文献
14.
The Hamiltonian of the magnetic superlattice with three-layer unit cell was treated within the Boson formalism. The Boson Green’s functions (BGFs) were derived and it was shown that the system for BGFs splits into two sets which lead to the energies with opposite signs, although the energies of elementary excitations are strictly only the positive ones. However, when corresponding energies are used, the correlation functions calculated from both sets are the same. All the physically relevant quantities: total energy of the system, ground state energy, layer magnetization and zero-point (quantum) fluctuations are derived analytically by using both sets, showing that they lead to the same expressions. The Hamiltonian was also diagonalized by the so-called “u-v” transformation of the operators. It is shown that in spite of formal independence of the approaches, there exists a close relationship between BGF and “u-v” transformations. 相似文献
15.
N.H. Dung N.P. Thuy N.A. Tuan N.T. Long N.N. Phuoc 《Journal of magnetism and magnetic materials》2008
Magnetic and structural properties in [MnPd/Co]10 multilayers deposited onto Si(1 1 1) substrates have been investigated. The dependences of anisotropy and exchange bias on the thicknesses of both MnPd and Co layers have been studied. In most of the samples, the out-of-plane magnetic anisotropy and both large out-of-plane and in-plane exchange biases have been observed at cryogenic temperature below the blocking temperature TB≈240 K. With appropriate MnPd and Co thicknesses, we have obtained samples with a large out-of-plane exchange bias along with a large out-of-plane magnetic anisotropy. The origin of the out-of-plane magnetic anisotropy in the samples has been suggested to be due to the formation of CoPd interfacial alloys which have tensile in-plane strains, while the spin structure of the antiferromagnetic layer at the interface which is believed to be responsible for exchange bias may be the same as that of the bulk material. Also, the present study shows that the interplay between the out-of-plane magnetic anisotropy and exchange bias is evident in our multilayers and plays an important role in the out-of-plane exchange-bias mechanism. 相似文献
16.
In this work we present a fractal analysis of the spin wave modes propagating in a Fibonacci quasiperiodic metamagnetic superlattices consisting of a ferromagnetic material (layer A being Fe) and a metamagnetic material (layer B being FeBr2). The spin wave modes are obtained in the exchange regime, using the transfer matrix technique. Our numerical results show that the power law for this system is independent of the dimensionless in-plane wavevector kxa, and that the spectrum present a multifractal characteristic, exhibiting several scale invariant windows for a fixed value of the in-plane wavevector. The results reported here can be experimentally observed by light scattering techniques. 相似文献
17.
Soft X-ray resonant magnetic scattering (SXRMS) has been used to investigate the microscopic magnetization reversal behavior of complex magnetic systems. SXRMS is a unique technique, providing chemical, spatial and magnetic sensitivity, which is not affected by external magnetic fields. The study of two selected thin magnetic heterostructures is presented, amorphous rare-earth transition metal alloys and perpendicular exchange coupled antiferromagnetic/ferromagnetic films. In the first system, the internal structure of magnetic stripe domains on nanometer length scales is obtained by measuring bi-dimensional (2D) scattering images. In the second system, the element specificity is exploited to identify the role of the uncompensated spins in the antiferromagnetic layer on the exchange coupling phenomena. Future trends are also discussed. 相似文献
18.
The magnetic properties of annealed Fe-Pt multilayer thin films with a broad composition range were investigated in order to identify the effects of composition and annealing temperature on the achievable coercive field, and to identify its maximum at low processing temperatures. Two types of multilayer systems were deposited as materials libraries to vary the composition from Fe20Pt80 to Fe75Pt25. The first type of multilayer was comprised of alternating opposing wedges, whereas the second type consisted of repeated uniform Fe and Pt layers interspersed periodically with Fe wedge layers. It was found that coercive fields μ0HC > 0.7 T can be achieved at an annealing temperature of about 300 °C (60 min) for both types of multilayers as long as the composition is close to 50:50. Higher annealing temperatures are needed for films, which deviate from this composition. Increasing the annealing temperature up to 700 °C leads to increased coercivity values. Multilayers with additional Fe layers showed increased remanence but reduced coercive fields. 相似文献
19.
Monte Carlo simulation of spin-wave excitation for the magnetic films with structure and interaction fluctuations 总被引:1,自引:0,他引:1
Monte Carlo simulation studies are performed to examine influence of structure and interaction fluctuations on magnetic properties of a ferromagnetic system modelled with a Heisenberg Hamiltonian. It is found that the spontaneous magnetization at low temperature for the multilayered films decreases with temperature in a Bloch law of spin-wave excitations. Both Bloch coefficient B and exponent b vary evidently because of a strong surface and size effect in the finite magnetic films with free boundaries. For the disordered bulk FCC magnet with periodic boundary, the Bloch T3/2 law is followed at low temperature and B is greatly influenced by the structure and interaction fluctuations. At the same time, Bloch coefficient B of the amorphous magnet with the coordination and interaction fluctuations has been derived. The simulated results are in good agreement with the theoretical predictions of spin-wave excitation, and explain the experimental facts well. 相似文献
20.
The magnetic hysteresis of Fe57Ni43/Si(100) with magnetic anisotropy induced by an external field has been studied by Brillouin light scattering (BLS). The results are compared with those of the magneto-optic-Kerr-effect (MOKE) measurement and the vibrating sample magnetometer (VSM). The BLS results show that the sample film has strong in-plane anisotropy. The angle between the magnetization and a 4.6 G applied magnetic field H reaches a maximum value of 45° when H lies along the hard axis. The coercivity and magnetic anisotropy field for the film obtained by the BLS are compared with the values obtained by the VSM and MOKE measurement. 相似文献