共查询到20条相似文献,搜索用时 718 毫秒
1.
A. Saffarzadeh 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,24(2):149-153
Spin-polarized tunneling in FMS/M/FMS double tunnel junctions where FMSs are ferromagnetic semiconductor layers and M is a
metal spacer is studied theoretically within the single-site coherent potential approximation (CPA). The exchange interaction
between a conduction electron and localized moment of the magnetic ion is treated in the framework of the s-f model. The spin polarization in the FMS layers is observed to oscillates as a function of the number of atomic planes in
the spacer layer. Amplitude of these oscillations decreases with increasing the exchange interaction in FMS layers.
Received 9 June 2001 and Received in final form 20 August 2001 相似文献
2.
M. Löhndorf A. Wadas R. Wiesendanger 《Applied Physics A: Materials Science & Processing》1997,65(4-5):511-515
Received: 14 August 1997/Accepted: 14 August 1997 相似文献
3.
The Hubbard model on fcc-type lattices is studied in the dynamical mean-field theory of infinite spatial dimensions. At intermediate
interaction strength finite temperature Quantum Monte Carlo calculations yield a second order phase transition to a highly
polarized, metallic ferromagnetic state. The Curie temperatures are calculated as a function of electronic density and interaction
strength. A necessary condition for ferromagnetism is a density of state with large spectral weight near one of the band edges.
Received: 6 August 1997 / Accepted: 20 August 1997 相似文献
4.
R.F.W. Herrmann J. Gerlach E.E.B. Campbell 《Applied Physics A: Materials Science & Processing》1998,66(1):35-42
Received: 30 July 1997/Accepted: 5 August 1997 相似文献
5.
N.N. Garif'yanov Y.V. Goryunov T. Mühge L. Lazar G.G. Khaliullin K. Westerholt I.A. Garifullin H. Zabel 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(4):405-407
We have studied superconducting and magnetic properties of sputtered Fe/Pb/Fe-trilayers. For a fixed Pb thickness and with changing Fe thickness, , a monotonic decrease of the superconducting transition temperature was observed. Magnetization measurements clearly showed that Fe remains ferromagnetic down to the monolayer range. A quantitative
comparison of with the theory of pair breaking by the exchange field reveals that the observed -suppression by the ferromagnetic Fe-layer is much weaker than expected. Possible reasons for the reduced -suppression in this system are discussed.
Received: 30 June 1997 / Revised: 20 August 1997 / Accepted: 16 December 1997 相似文献
6.
Received: 25 August 1997/Accepted: 23 October 1997 相似文献
7.
We present a series of rigorous examples of the Kondo lattice model that exhibit full ferromagnetism in the ground state.
The models are defined in one-, two- and three-dimensional lattices, and are characterized by a range of hopping terms, specific
electron filling, and large ferromagnetic coupling. Our examples show that a sufficient strong but finite exchange coupling
between conduction electrons and localized spins could overcome the competition from mobility of a finite density of electrons
and drive the system from a paramagnetic phase to a ferromagnetic phase. We also establish a relation of ferromagnetism between
the Hubbard model and Kondo lattice model. Meanwhile some rigorous results on ferromagnetism in the corresponding Hubbard
model are presented.
Received: 10 September 1997 / Revised: 15 October 1997 / Accepted: 17 October 1997 相似文献
8.
O.M. Artamonov S.N. Samarin J. Kirschner 《Applied Physics A: Materials Science & Processing》1997,65(6):535-542
Received: 21 March 1997/Accepted 12 August 1997 相似文献
9.
H.C. Nägerl W. Bechter J. Eschner F. Schmidt-Kaler R. Blatt 《Applied physics. B, Lasers and optics》1998,66(5):603-608
Received: 6 August 1997/Revised version: 21 October 1997 相似文献
10.
W.G. Schmidt 《Applied Physics A: Materials Science & Processing》1997,65(6):581-586
Received: 21 March 1997/Accepted: 12 August 1997 相似文献
11.
M. Goldman 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(2):147-156
We describe the theory of EPR in a crystal field multiplet under sample spinning. Berry phases arise because the crystal field
is of lower symmetry than the full rotation group. The formal development is limited to pure J multiplets, crystal field doublets, and field and rotation axes parallel to a principal axis.
Received: 4 August 1997 / Received in final form: 19 December 1997 /
Accepted: 28 January 1998 相似文献
12.
M. Rusu 《Applied Physics A: Materials Science & Processing》1998,66(3):357-361
Received: 1 July 1997/Accepted: 6 August 1997 相似文献
13.
Y.-Z. Wan D.W. Zhang Z.-J. Liu J.-T. Wang 《Applied Physics A: Materials Science & Processing》1998,67(2):225-231
Received: 28 August 1997/Accepted: 18 November 1997 相似文献
14.
Received: 13 May 1997/Revised version: 1 August 1997 相似文献
15.
Received: 30 May 1997/Revised version: 26 August 1997 相似文献
16.
Received: 30 May 1997/ 27 August 1997 相似文献
17.
Weichang Zhao Hua Jin Mingliang Tian Keqing Ruan Li Yang Liezhao Cao 《Applied Physics A: Materials Science & Processing》1998,66(4):451-454
Received: 5 August 1997/Accepted: 2 October 1997 相似文献
18.
S. Ispolatov P.L. Krapivsky S. Redner 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(2):267-276
A model for the evolution of the wealth distribution in an economically interacting population is introduced, in which a specified
amount of assets are exchanged between two individuals when they interact. The resulting wealth distributions are determined
for a variety of exchange rules. For “random” exchange, either individual is equally likely to gain in a trade, while “greedy”
exchange, the richer individual gains. When the amount of asset traded is fixed, random exchange leads to a Gaussian wealth
distribution, while greedy exchange gives a Fermi-like scaled wealth distribution in the long-time limit. Multiplicative processes
are also investigated, where the amount of asset exchanged is a finite fraction of the wealth of one of the traders. For random
multiplicative exchange, a steady state occurs, while in greedy multiplicative exchange a continuously evolving power law
wealth distribution arises.
Received: 13 August 1997 / Revised: 31 December 1997 / Accepted: 26
January 1998 相似文献
19.
Received: 25 April 1997/Revised version: 1 August 1997 相似文献
20.
K. Kolwas 《Applied physics. B, Lasers and optics》1998,66(4):467-470
Received: 27 August 1997/Revised version: 7 November 1997 相似文献