共查询到20条相似文献,搜索用时 15 毫秒
1.
R.V. Chopdekar M. Liberati L.F. Kourkoutis B.B. Nelson-Cheeseman A. Doran D.A. Muller 《Journal of magnetism and magnetic materials》2010,322(19):2915-2921
Magnetic order and coupling at the interfaces of highly spin polarized Fe3O4 heterostructures have been determined by surface sensitive and element specific soft X-ray spectroscopy and spectro-microscopy techniques. At ambient temperature, the interface between paramagnetic CoCr2O4 or MnCr2O4 and ferrimagnetic Fe3O4 isostructural bilayers exhibits long range magnetic order of Co, Mn and Cr cations which cannot be explained in terms of the formation of interfacial MnFe2O4 or CoFe2O4. Instead, the ferrimagnetism is induced by the adjacent Fe3O4 layer and is the result of the stabilization of a spinel phase not achievable in bulk form. Magnetism at the interface region is observable up to 500 K, far beyond the chromite bulk Curie temperature of 50-95 K. 相似文献
2.
3.
Sergei O. Filnov Dmitry A. Estyunin Ilya I. Klimovskikh Tatiana P. Estyunina Vladimir A. Golyashov Anton S. Tarasov Nikolay N. Kosyrev Vasily A. Komarov Gennady S. Patrin Anna A. Rybkina Oleg Yu Vilkov Alexander M. Shikin Oleg E. Tereshchenko Ratibor G. Chumakov Alexey M. Lebedev Artem G. Rybkin 《固体物理学:研究快报》2024,18(3):2300336
The utilization of graphene on silicon carbide (SiC) substrates holds substantial promise for advancements in spintronics and nanoelectronics. Furthermore, incorporating magnetic metals provides an optimal framework for probing fundamental physical phenomena. The approach to developing such systems is in situ intercalation of graphene with magnetic metals. Herein, the electronic structure is analyzed and the magnetic properties of the system are synthesized by the thermal decomposition of 6H-SiC(0001) surface and subsequent intercalation of graphene with cobalt (Co) and iron (Fe) atoms. X-ray photoemission spectroscopy and low-energy electron diffraction are employed to control the synthesis and metal intercalation processes. The morphological characteristics of the synthesized system are studied by means of atomic force microscopy. The findings derived from magneto-optic Kerr effect measurements reveal a homogeneous ferromagnetic ordering at room temperature. Angle-resolved photoemission spectroscopy is used to ascertain the impact of intercalation on graphene's electronic structure. The results of this study are essential for the development of graphene-based spintronics and nanoelectronic devices as well as for fundamental studies in magnetic graphene systems. 相似文献
4.
Arshak L. Vartanian Anna L. Asatryan Albert A. Kirakosyan 《Physica E: Low-dimensional Systems and Nanostructures》2005,28(4):545-551
The hot-electron energy-loss rate (ELR) conditioned by confined and interface polar-optical (PO) phonons for a quasi-one-dimensional cylindrical quantum wire embedded in a dielectric medium is investigated analytically. It is shown that the inclusion of the PO-phonon confinement effects is crucial for accurate calculation of the ELR in quantum wire. Taking into account the nonequilibrium phonon populations, the hot-electron ELR is derived by a model, which includes the lowest subband occupation and the phonon confinement effects. The contribution of intersubband transitions to electron ELR for the GaAs quantum wire embedded in AlxGa1−xAs is estimated. The extrema on the ELR dependences on electron density are obtained. 相似文献
5.
Batobolot Zhalsaraevich Zhalsaraev 《X射线光谱测定》2020,49(4):480-492
Background suppression is discussed in wavelength-dispersive polarization X-ray spectrometer (WDPXRS), in which the goniometer scans in plane perpendicular to primary and secondary beams. Background suppression coefficients in WDPXRS and energy-dispersive polarization X-ray spectrometer are determined by different expressions (in “The scattering suppression of X-rays with energy of 20–200 keV in spectrometers with Barkla polarizers,” doi: 10.1002/xrs.3046 ). It is proposed to install silicon drift detectors in WDPXRS and implement energy-dispersive and wavelength-dispersive modes in one channel. 相似文献
6.
B. D. Hennings K. D. D. Rathnayaka D. G. Naugle I. Felner 《Physica C: Superconductivity and its Applications》2002,370(4):253-258
The thermal conductivity and thermopower are reported for a hole doped Eu1.5Ce0.5RuSr2Cu2O10+δ sample that has been annealed at 1100 K under an oxygen pressure of 54 atm. At Tc=45 K superconductivity and weak ferromagnetism coexist (Tm=180 K). Weak features in the thermopower, S(T), and thermal conductivity, κ(T), are observed both at Tm and at T*=140 K. The thermopower begins to decrease sharply toward zero at Tc, and there is an extremely sharp increase of about 30% in the thermal conductivity at Tc. This “first order” transition may be related to the sudden appearance of a spontaneous vortex phase at Tc. A small shoulder is observed in κ(T) in the temperature range T=5–13 K. 相似文献
7.
We analyze for the first time the coupled influence of band mixing, strain, and piezoelectricity on electronic structure, eigenstates, and optical transition strengths for InAs/GaAs quantum-ring structures. It is shown that band mixing and strain alter the level energies and optical absorption coefficients significantly. 相似文献
8.
F. Abbattista R. Albanese C. Delprete G. Genta R. Gerbaldo G. Ghigo L. Gozzelino E. Mezzetti A. B. Mosolov S. Ronchetti M. Vallino 《Il Nuovo Cimento D》1994,16(12):2087-2094
Summary This paper deals with a comparison of chemical, physical and mechanical characterisation of YBCO samples obtained with Temporary-Liquid-Densification
Melt Growth (TLDMG). Ba2YCu3O7-x
+50% excess BaY2CuO5 pellets were prepared from different Ba-Y-Cu-O system phases, suitable to produce during the heat treatment temporary liquids
at temperatures lower than 1000°C. A mechanical characterisation was performed in zero-field-cooling and field-cooling condition,
showing hysteretic behaviour and creep of the levitation force. Measurements of magnetic hysteresis cycles in low fields and
a.c. susceptibility were also performed. Some mechanical applications (high-speed electric motor and flywheel energy accumulator)
were built and tested. The work now proceeds on two new industrial applications of melt-processed HTSC materials.
Paper presented at the “VII Congresso SATT? Torino, 4–7 October 1994. 相似文献
9.
D. Zanghi A. Traverse J.-P. Dallas E. Snoeck 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(1):171-179
Ni ions were implanted in bulk AlN with the goal to form embedded metallic clusters. Combining several characterisation techniques
such as X-ray absorption spectroscopy, X-ray diffraction and high resolution transmission electron microscopy, we determined
the lattice parameter of the Ni clusters that display a fcc crystalline structure. The average size increases when the ion
fluence is increased or after a thermal treatment. Thanks to moiré fringes observed by high resolution transmission electron
microscopy and to satellite peaks seen on the diffraction patterns, we concluded that the annealed Ni clusters orientate their
(002) planes on the (101) of AlN. Moreover, the satellite positions allowed us to calculate Ni cluster average diameters,
that are in agreement with average sizes deduced by X-ray absorption spectroscopy.
Received 25 August 1999 and Received in final form 8 February 2000 相似文献
10.
Flux of X-ray radiation emitted from the Ta plasma, produced by the fundamental (1ω) and the third harmonic (3ω) frequencies of the high-power iodine laser PALS, was studied in dependence on the laser focus position. One or two (three) maxima, corresponding to the hard or soft component of the emitted spectrum, can appear, according to the experimental conditions. These dependencies are compared with those published by other authors, and also with our results concerning the highly charged ion generation. At laser intensities above I L~ 1014 W/cm2, the participation of non-linear processes in the pre-formed plasma was confirmed. 相似文献
11.
A comparison has been made of irreversibility temperature determined by four different methods in few specimens of lead (type-I)
and niobium (type-II). The merger ofM
ZFC(T) andM
FC(T) curves giveT
r(H) values lower than those evident from vanishing the hysteresis in isothermal DC magnetization. The identification of peak
temperature inx″
H
(T) data withT
r(H) is appropriate only if the contribution from changes in the normal state electrodynamics can be isolated and the peak is
narrow. The appearance of differential paramagnetic effect inx′
H
(T) data is adequate to imply reversibility, however, its efficacy to precisely locate irreversibility line remains to be established. 相似文献
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13.
A. Szolnoki M. Perc 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(3):337-344
We study the evolution of cooperation in structured populations within popular models of social dilemmas, whereby simple coevolutionary
rules are introduced that may enhance players abilities to enforce their strategy on the opponent. Coevolution thus here refers
to an evolutionary process affecting the teaching activity of players that accompanies the evolution of their strategies.
Particularly, we increase the teaching activity of a player after it has successfully reproduced, yet we do so depending on
the disseminated strategy. We separately consider coevolution affecting either only the cooperators or only the defectors,
and show that both options promote cooperation irrespective of the applied game. Opposite to intuitive reasoning, however,
we reveal that the coevolutionary promotion of players spreading defection is, in the long run, more beneficial for cooperation
than the likewise promotion of cooperators. We explain the contradictive impact of the two considered coevolutionary rules
by examining the differences between resulting heterogeneities that segregate participating players, and furthermore, demonstrate
that the influential individuals completely determine the final outcome of the games. Our findings are immune to changes defining
the type of considered social dilemmas and highlight that the heterogeneity of players, resulting in a positive feedback mechanism,
is a fundamental property promoting cooperation in groups of selfish individuals. 相似文献
14.
Hall A Collaboration John J. LeRose C.W. de Jager R.J. Feuerbach D.W. Higinbotham B. Reitz A. Acha P. Markowitz P. Bydovský M. Sotona C.C. Chang E. Cisbani F. Cusanno S. Frullani F. Garibaldi R. De Leo L. Lagamba S. Marrone M. Iodice G.M. Urciuoli 《Nuclear Physics A》2008,804(1-4):116-124
Results are presented from a new experiment (E94-107) in Hall A of the Thomas Jefferson National Accelerator Facility (JLab) producing , , and using electroproduction, (e,e′K+). In the hypernuclear missing-mass spectrum the experiment achieves very good energy resolution (670 keV FWHM) by exploiting the characteristics of the High Resolution spectrometer pair and the exceptional beam quality available at JLab. The spectrometers were used with the addition of an INFN provided pair of septum magnets to reach the desired small angles. Also, the Hall A standard complement of equipment was further augmented by the addition of a Ring Imaging Cherenkov detector (RICH) to achieve the best possible kaon identification. 相似文献
15.
s 《Superlattices and Microstructures》2001,29(6):385
A variational formalism for calculating the binding and the transition energies between 1 s - and 2 p ± -like states of a shallow donor in cylindrical pills of GaAs low-dimensional systems, under the action of the electric and magnetic fields applied in the axial direction, is presented. Results were obtained for several values of the magnetic field as a function of the system geometry and the applied electric field. Within the two-dimensional limits, the theoretical results for the 1 s– 2 p + transition energies are in good agreement with infrared-magnetospectroscopy measurements on donor doped quantum-wells. 相似文献
16.
K. Mahmoud Aghdami F. Prati P. Caccia G. Tissoni L. A. Lugiato R. Kheradmand H. Tajalli 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(3):447-455
We compare three different switching techniques for the control of cavity solitons in a VCSEL-based cavity soliton laser,
one
incoherent and the other two semicoherent with different injection
frequencies. We show that the switching dynamics and energies can be
very different depending on the type of injection. 相似文献
17.
H. Zhao Z.-Y. Gao 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(1):95-101
In this paper, we investigate cascade defense and control
in scale free networks via navigation strategy. It is found
that with an appropriate parameter a, which is tunable in
controlling the effect of degree in the navigation strategy, one can
reduce the risk of cascade break down. By checking the distribution
of efficient betweenness centrality (EBC) and the average EBC
of vertices with degree k, the validity can be guaranteed. Despite
the advantage of cascade defense, the degree based navigation
strategy may also lead to lower network efficiency. To avoid this
disadvantage, we propose a new navigation strategy. Importantly and
interestingly, the new strategy can defend cascade break down
effectively even without reducing the network efficiency.
Distribution of the EBC and EBC-degree correlation of the new
strategy are also investigated to explain the effectiveness in
cascade defense. 相似文献
18.
J. Carbonell V. A. Karmanov M. Mangin-Brinet 《The European Physical Journal A - Hadrons and Nuclei》2009,39(1):53-60
For a relativistic system of two scalar particles, we find the Bethe-Salpeter amplitude in Minkowski space and use it to compute
the electromagnetic form factor. The comparison with Euclidean space calculation shows that the Wick rotation in the form
factor integral induces errors which increase with the momentum transfer Q2. At JLab domain (Q
2 = 10 GeV^2/c2), they are about 30%. Static approximation results in an additional and more significant error. On the contrary, the form
factor calculated in light-front dynamics is almost indistinguishable from the Minkowski space one. 相似文献
19.
G. Bouglet C. Ligoure 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(1):137-147
Small angle X-ray and neutron scattering data on an effective three-component lamellar phase composed of water, a non adsorbing
water-soluble polymer (polyvynilpyrolidone), fluid membranes, made from a mixture of a cationic surfactant (cetylpiridiumchloride)
and a cosurfactant (hexanol), are presented for various membrane as well as polymer concentrations. The data are fitted with
a recently proposed model which takes into account the geometry and the fluctuations of these periodic structures. This allows
a quantitative study of the polymer contribution to the smectic compression modulus of the lamellar phase. Four different regimes of polymer confinement are expected. The associated variations in are compared to a recent theoretical model, which predicts the polymer-mediated contribution to the smectic compression modulus.
Received 20 January 1998 相似文献
20.
Exact solution of the one-dimensional spin-\frac{\mathsf 3}{\mathsf 2} Ising model in magnetic field
A. Avella F. Mancini 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(4):527-539
In this paper, we study the Ising model with general spin S in
presence of an external magnetic field by means of the equations of
motion method and of the Green's function formalism. First, the
model is shown to be isomorphic to a fermionic one constituted of
2S species of localized particles interacting via an intersite
Coulomb interaction. Then, an exact solution is found, for any
dimension, in terms of a finite, complete set of eigenoperators of
the latter Hamiltonian and of the corresponding eigenenergies. This
explicit knowledge makes possible writing exact expressions for the
corresponding Green's function and correlation functions, which turn
out to depend on a finite set of parameters to be self-consistently
determined. Finally, we present an original procedure, based on
algebraic constraints, to exactly fix these latter parameters in the
case of dimension 1 and spin
. For this latter case and,
just for comparison, for the cases of dimension 1 and spin
[F. Mancini, Eur. Phys. J. B 45, 497 (2005)] and
spin 1 [F. Mancini, Eur. Phys. J. B 47, 527 (2005)],
relevant properties such as magnetization 〈S 〉 and
square magnetic moment 〈S2 〉, susceptibility and
specific heat are reported as functions of temperature and external
magnetic field both for ferromagnetic and antiferromagnetic
couplings. It is worth noticing the use we made of composite
operators describing occupation transitions among the 3 species of
localized particles and the related study of single, double and
triple occupancy per site. 相似文献