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排序方式: 共有299条查询结果,搜索用时 15 毫秒
291.
We report on the dynamics of magnetic domain structure conversions exhibited by soft magnetic thin-film elements of elementary geometrical shape (square, disc, triangle) when exposed to a strong external magnetic field. Starting from flux closure vortex patterns, the magnetic structures evolve towards an in-plane saturated state under the influence of an external field. This irreversible and nucleation-free magnetization process occurs on the time scale of picoseconds. The details of this conversion are investigated by means of a time-resolved micromagnetic finite element modeling. We find a sensitive dependence of the temporal evolution of the magnetic structure on the value of the damping parameter in Gilbert's equation of motion. In the case of high damping, domain wall motion dominates the process, while lower damping leads to the formation of a 360° wall which collapses by emitting magnetization waves. It is shown that the mobility of vortices is generally much lower than that of domain walls. The calculations indicate that at a low damping, a magnetic vortex can act almost as a source for concentric waves in ferromagnetic thin-film elements. 相似文献
292.
W. Kamke B. Kamke Z. Wang H. U. Kiefl I. V. Hertel 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1986,2(2):159-160
Discrepancies in the observed lineshapes and shifts of the resonance lines from Intramolecular Penning Ionization in aromates seeded into argon measured by two different groups are attributed to the different operating conditions in the molecular beam expansions used. Results are reported that clarify the influence of the premixing and expansion parameters on the observed structures. 相似文献
293.
H. W. Hermann I. V. Hertel G. Marowsky 《Applied Physics A: Materials Science & Processing》1978,15(2):185-190
Electron energy loss studies of POPOP andp-terphenyl in the vapor phase at an incident electron energy of 25 eV have been performed. The spectra covering an energy
loss between 0 and 9 eV revealed a considerable initial triplet population under electron impact excitation. The implications
for electron-beam pumped vapor phase dye lasers are discussed. 相似文献
294.
H. Lippert V. Stert L. Hesse C.P. Schulz W. Radloff I.V. Hertel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):445-448
The H atom transfer reaction in electronically excited indole(NH
3
)
n
clusters is studied in pump-probe experiments with femtosecond laser pulses. By applying different probe photon energies
we are able to detect the dissociation products (NH
3
)
n - 1
NH
4
for n
= 1-6. Furthermore we show that the analysis of the corresponding ion signals is not distorted by contributions from larger cluster
ions due to evaporation of NH
3
molecules. The formation times of the products are ca. 140ps for n
= 2-4 and about 80ps for n
= 5, 6.
Received 30 April 2002 / Received in final form 29 May 2002 Published online 13 September 2002 相似文献
295.
Seemann KM Garcia-Sanchez F Kronast F Miguel J Kákay A Schneider CM Hertel R Freimuth F Mokrousov Y Blügel S 《Physical review letters》2012,108(7):077201
We analyze the origin of the electrical resistance arising in domain walls of perpendicularly magnetized materials by considering a superposition of anisotropic magnetoresistance and the resistance implied by the magnetization chirality. The domain wall profiles of L1(0)-FePd and L1(0)-FePt are determined by micromagnetic simulations based on which we perform first-principles calculations to quantify electron transport through the core and closure region of the walls. The wall resistance, being twice as high in L1(0)-FePd than in L1(0)-FePt, is found to be clearly dominated in both cases by a high gradient of magnetization rotation, which agrees well with experimental observations. 相似文献
296.
297.
Vladimir Arkhipov Heinz Bässler Evgenia Emelyanova Dirk Hertel Vidmantas Gulbinas Lewis Rothberg 《Macromolecular Symposia》2004,212(1):13-24
In conjugated polymers, a majority of photogenerated charges form metastable geminate pairs (GPs), of which only some fraction can dissociate completely. Both the yield of GP photogeneration and the probability of further dissociation of GPs into free charges depend upon an external electric field. In the present article we discuss several experimental methods to detect the existence of geminate pairs such as delayed field collection of charges, field quenching of fluorescence, and field-assisted photoinduced optical absorption. It is shown that the field dependences of the exciton dissociation into GPs and of the free carrier photogeneration yield are rather similar. This is in contrast with the traditional Onsager theory, which assumes field-independent yield of primary photoionization and disregards the field dependence of the initial separations between carriers in GPs. 相似文献
298.
299.