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1.
Using polarized neutron reflectivity (PNR) measurements together with associated simulation, magnetic structures of two Ni80Fe20 (1 1 1)/Ru (0 0 0 1) multilayer samples with Ru thickness of 9 and 21 Å were investigated under various external magnetic fields at room temperature. The results reveal the existence of layer thickness, interface roughness, magnetic moment, interlayer coupling angle and non-collinear coupling. The former three are independent of Ru thickness; while the latter two are strongly dependent of Ru thickness. 相似文献
2.
We consider a model for magnetic memory that consists of strongly coupled dipolar or antiferromagnetic (AF) pairs with inequivalent perpendicular anisotropy K1 and K2. For appropriate parameter values, determined in this work, they have two inequivalent storage states with zero net magnetic moment. Both analytical and numerical calculations are performed, in some cases yielding different results because of relaxation effects (i.e., a dependence on the damping parameter α). Hysteresis loops for a wide variety of parameter values are obtained, both for the AF case and the dipole case. An Appendix gives analytic results for slightly non-collinear spins in an applied field, which were used to test the numerical results. 相似文献
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In ultrathin films, due to the thermal activation and temperature dependencies of the magnetic parameters, magnetization reversal processes are strongly affected by thermal effects. We analyze changes of domain periods of ultrathin cobalt and L10 films in a wide temperature range. With regard to the temperature dependencies of the film magnetic parameters we calculate the equilibrium stripe period as a function of temperature. It is shown that on film heating the equilibrium domain structure (DS) period decreases and at the reorientation phase transition (RPT) approaches its minimal value corresponding to the temperature independent period of the sinusoidal domain structure. Just below the RPT temperature (or thickness) the stripe domain period was found to exponentially decrease with temperature. Irreversible temperature changes of the domain period affected by coercivity are also discussed. 相似文献
5.
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
6.
S.A. Nepijko M. Klais G. Schönhense N. Cramer Z. Celinski C.M. Schneider S. Zennaro N. Zema N.N. Sedov 《Applied Physics A: Materials Science & Processing》2003,76(5):809-815
Micromagnetic properties of the Fe19Ni81 (5 nm)/NiO (50 nm)/Fe19Ni81 (30 nm) structured system have been investigated in a photoemission electron microscope in the magnetic X-ray circular dichroism
operating mode. The microstructured Fe19Ni81 (5 nm) film contained two-dimensional islands with the aspect ratio varying from 1:1 to 10:1, and the linear size of their
long axis comprised 24, 12 and 6 μm. It is shown that the magnetic domains have the direction of magnetization preferentially
parallel and antiparallel to the magnetic field direction in which this system was prepared. Their number is determined by
the particles’ sizes, their shape as well as by the direction of the external magnetizing field and can be characterized by
a non-monotonic size dependence. The magnetization of domains with different lateral sizes was found to be 0.4 T with an accuracy
better than 20%.
Received: 29 May 2002 / Accepted: 17 July 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +49-6131/392-3807, E-mail: nepijko@mail.uni-mainz.de 相似文献
7.
A. Athanassiou K. Lakiotaki V. Tornari S. Georgiou C. Fotakis 《Applied Physics A: Materials Science & Processing》2003,76(1):97-100
This work examines volume changes at the sub-micron scale, induced photochemically in polymeric matrices doped with photochromic
molecules. To achieve this, spiropyran is employed as a photochromic molecule embedded in polyethylmethacrylate-co-methylacrylate (PEMMA) matrices. Spiropyran can be reversibly interconverted to merocyanine, its coloured isomer, by irradiation at 248 nm
and 532 nm, correspondingly. It is demonstrated that the interconversion between the two forms activates volume changes in
the polymer matrix. To this end, off-axis reflection holographic interferometry is employed as a sensitive probe of the induced
volume changes. This scheme provides a novel method for controlling sub-micron volume changes reversibly, as required in several
microactuator designs.
Received: 17 April 2002 / Accepted: 18 April 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +30-810/391-318, E-mail: nassia@iesl.forth.gr 相似文献
8.
9.
Growth of Semi-Insulating GaN Using N2 as Nucleation Layer Carrier Gas Combining with an Optimized Annealing Time 下载免费PDF全文
Semi-insulating (SI) GaN is grown using N2 as the nucleation layer (NL) carrier gas combined with an optimized annealing time by metalorganic chemical vapour deposition. Influence of using 1-12 and N2 as the NL carrier gas is investigated in our experiment. It is found that the sheet resistance of unintentionally doped GaN can be increased from 10^4 Ω/sq to 10^10 Ω/sq by changing the NL carrier gas from 1-12 to N2 while keeping the other growth parameters to be constant, however crystal quality and roughness of the tilm are degraded unambiguously. This situation can be improved by optimizing the NL annealing time. The high resistance of GaN grown on NL using N2 as the carrier gas is due to higher density of threading dislocations caused by the higher density of nucleation islands and small statistic diameter grain compared to the one using 1-12 as carrier gas. Annealing the NL for an optimized annealing time can decrease the density of threading dislocation and improve the tilm roughness and interface of AlGaN/GaN without degrading the sheet resistance of as-grown GaN signiticantly. High-quality SI GaN is grown after optimizing the annealing time, and AlGaN/GaN high electron mobility transistors are also prepared. 相似文献
10.
Yusaku Iwasawa Tetsuroh Shirasawa Takehiro Nojima Toshio Takahashi Masuaki Matsumoto Koichi Akimoto Hiroshi Sugiyama 《Applied Surface Science》2008,254(23):7803-7806
The structure of buried Si(1 1 1)-5 × 2-Au capped with amorphous Si was investigated using surface X-ray diffraction. It was found that the 5 × 2 structural periodicity is kept under the amorphous Si from the in-plane measurement. Furthermore, the intensity variation along the fractional-order rod indicates that Au atoms are located almost on the same plane. 相似文献