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301.
M. Romeo V. Da Costa F. Bardou 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(4):513-525
The lognormal distribution describing, e.g., exponentials of Gaussian random variables is one of the most common statistical distributions in physics. It can exhibit
features of broad distributions that imply qualitative departure from the usual statistical scaling associated to narrow distributions.
Approximate formulae are derived for the typical sums of lognormal random variables. The validity of these formulae is numerically
checked and the physical consequences, e.g., for the current flowing through small tunnel junctions, are pointed out.
Received 8 November 2002 / Received in final form 17 March 2003 Published online 7 May 2003 相似文献
302.
X.F. Han X.Q. Zhang Z.M. Zeng F.F. Li L.X. Jiang R. Sharif Y.D. Yao 《Journal of magnetism and magnetic materials》2006
Both single-barrier magnetic tunnel junctions (SBMTJs) and double-barrier magnetic tunnel junctions (DBMTJs) with an amorphous hardcore structure of Co60Fe20B20/Al–O/Co60Fe20B20 were microfabricated. A high TMR ratio of 102.2% at 4.2 K was observed in the SBMTJs after annealing at 265 °C for 1 h. High TMR ratio of 56.2%, low junction resistance-area product RS of 4.6 kΩ μm2, small coercivity HC=25 Oe, and relatively large bias-voltage-at-half-maximum TMR with the value V1/2 greater than 500 mV at room temperature (RT) had been achieved in such Co–Fe–B SBMTJs. Whereas, high TMR ratio of 60% at RT and 89% at 30 K, low junction resistance-area product RS of 7.8 kΩ μm2 at RT and 8.3 kΩ μm2 at 30 K, low coercivity HC=8.5 Oe at RT and HC=14 Oe at 30 K, and relatively large bias-voltage-at-half-maximum TMR with the value V1/2 greater than 1150 mV at RT had been achieved in the Co–Fe–B DBMTJs. Temperature dependence of the TMR ratio, resistance, and coercivity from 4.2 K to RT, and applied voltage dependence of the TMR ratio and resistance at RT for such amorphous MTJs were also investigated. 相似文献
303.
S. Schneider S. Krewald Ulf-G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2006,28(1):107-113
A resonance model for two-pion production in the pion-nucleon reaction is developed that includes information obtained in
the analysis of pion-nucleon scattering in a meson-exchange model. The baryonic resonances Δ(1232), N*(1440), N*(1520), N*(1535), and N*(1650) are included. The model reproduces the total cross-sections up to kinetic energies of the incident pion of 400MeV and
obtains the shapes of the differential cross-sections in reasonable agreement with the data. 相似文献
304.
A. Sibirtsev J. Haidenbauer H. -W. Hammer S. Krewald 《The European Physical Journal A - Hadrons and Nuclei》2006,27(3):269-285
A study of the strangeness production reaction pp → pK+Λ for excess energies of ε≤150MeV, accessible at high-luminosity accelerator facilities like COSY, is presented. Methods to
analyze the Dalitz plot distribution and angular spectra in the Jackson and helicity frames are worked out and suitable observables
for extracting information on low-lying resonances that couple to the KΛ system and for determining the Λp effective-range parameters from the final-state interaction are identified and discussed. Furthermore, the chances for identifying
the reaction mechanism of strangeness production are investigated. 相似文献
305.
V. Markovich G. Jung M. Belogolovskii Y. Yuzhelevski G. Gorodetsky Ya. M. Mukovskii 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(4):587-592
Transport properties of self-doped La0.89MnO3 single crystals with
Néel temperature of TN ≈139 K have been investigated in wide temperature
range 10–300 K. Data suggests that current at low temperature is conducted through a
strongly temperature-dependent, but almost bias independent channel operating in
parallel with a bias controlled but temperature independent channel. The first channel
is associated with transport across an insulating antiferromagnetic matrix while the
latter one represents tunnel conductivity through intrinsic tunnel junctions appearing
due to interruption of conducting percolating paths by phase separated insulating
inclusions. Tunnel character of the conductivity manifests itself in nonlinear
current-voltage characteristics and appearance of a zero-bias anomaly in the form of a
prominent conductance peak in the vicinity of zero bias. Zero bias anomaly and
V-shaped characteristics of the differential conductance at high voltages are ascribed
to the formation of local magnetic states in the insulating region of the tunneling
junction. 相似文献
306.
X.Y. Chen B. Yang T. Zhu K.H. Wong J.M. Liu Z.G. Liu 《Applied Physics A: Materials Science & Processing》2002,74(4):567-569
(110)-textured MgO films were grown on Si (100) with etching and without etching by pulsed laser deposition. The deposited
MgO films were shown to be droplets-free. The MgO film was used as a buffer layer to further grow Pt film on Si (100). A completely
(110)-oriented Pt film was obtained on such a buffer layer and its surface is very smooth with a roughness of about 7.5 nm
over 5×5 μm. This can be used as a new oriented Pt electrode on silicon for devices.
Received: 23 January 2001 / Accepted: 27 April 2001 / Published online: 27 June 2001 相似文献
307.
Maowang Lu Lide Zhang Yunxia Jin Xiaohong Yan 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(4):565-570
We study the spin-dependent transport properties of the nanostructures consisting of realistic magnetic barriers produced
by the deposition of ferromagnetic stripes on heterostructures. It is shown that, only in the nanostructures with symmetric
magnetic field with respect to the magnetic-modulation direction, electrons exhibit a considerable spin-polarization. It is
also shown that the degree of the electron spin polarization is greatly dependent on the ferromagnetic stripe and its position
relative to the 2DEG. A much larger electron-spin polarization can be obtained by properly fabricating the ferromagnetic stripe
and by adjusting its distance above the 2DEG.
Received 27 December 2001 and Received in final form 13 March 2002 Published online 25 June 2002 相似文献
308.
Zhenhong Dai Jinzuo Sun Lide Zhang Maowang Lu Zuohong Li Shiyong Huang 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):141-145
Artificial molecules, namely laterally coupled quantum dots with a three-dimensional spherical confinement potential well
of radius R and depth V
0, were studied by the unrestricted Hartree-Fock-Roothaan (UHFR) method. By varying the distance d between the centers of the two coupled quantum dots, the transition from the strong coupling situation to the weak one is
realized. Hund's rule, suitable for a single quantum dot is destroyed in certain conditions in the artificial molecule. For
example, in the few-electron system of the strongly coupled quantum-dot molecule, a transformation of spin configuration has
been found.
Received 8 March 2002 / Received in final form 29 May 2002 Published online 17 September 2002 相似文献
309.
P.-A. Hervieux A. Benabbas V. Halté J.-Y. Bigot 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):185-189
The electronic temperature dependence of the optical
absorption of silver nanoparticles is investigated in the
framework of the time-dependent local-density approximation at
finite temperature. Below the spectral region of interband
transitions, we have found that the electronic temperature leads
to a broadening and spectral shift of the surface plasmon
resonance. The calculated differential transmission is in good
agreement with recent experimental measurements obtained with
time resolved pump-probe techniques. 相似文献
310.
T. Döppner S. Teuber Th. Diederich Th. Fennel P. Radcliffe J. Tiggesbäumker K. H. Meiwes-Broer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):157-160
Lead clusters are exposed to strong femtosecond light
pulses. The dependence of the recoil energy on the charge state
of the atomic ion is now investigated using a new detection
setup, i.e., a Thomson
analyser. First results show that in contrast to laser-induced
overdense plasmas at surfaces the recoil energy distribution
appears much narrower. Comparing free lead clusters with lead
clusters embedded in large helium droplets, the charging
dynamics show distinct differences on the femtosecond time
scale. In the embedded case the maximum ionization enhancement
is reached earlier. 相似文献