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1.
R. Gonczarek M. Krzyzosiak A. Gonczarek 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(3):299-308
In this paper we find and present on diagrams in the coordinates of η=2t1/t0 (the ratio of the second and the first nearest
neighbor hopping integrals) and n (the carrier concentration) the
areas of stability for the superconducting spin-singlet s-
and d-wave and the spin-triplet p-wave order
parameters hatching out during the phase transition from the normal
to the superconducting phase. The diagrams are obtained for an
anisotropic two-dimensional superconducting system with a relatively
wide partially-filled conduction band. We study a tight-binding
model with an attractive nearest neighbor interaction with the
amplitude V1, and the on-site interaction (with the amplitude
V0) taken either as repulsive or attractive. The problem of the
coexistence of the s-, p- and d-wave order
parameters is addressed and solved for chosen values of the ratio
V0/V1. A possible island of stability of the d-wave
order parameter in the s-wave order parameter environment for
a relatively strong on-site interaction is revealed. The triple
points, around which the s-, d-, and p-wave
order parameters coexist, are localized on diagrams. It is shown
that results of the calculations performed for the two-dimensional
tight-binding band model are dissimilar with some obtained within
the BCS-type approximation. 相似文献
2.
王猛 胡正国 徐瑚珊 孙志宇 王建松 肖国青 詹文龙 张雪荧 李琛 毛瑞士 张宏斌 赵铁成 徐治国 王玥 陈若富 黄天衡 高辉 贾飞 付芬 高启 韩建龙 章学恒 郑川 余玉洪 樊瑞睿 李波 郭忠言 《中国物理 C》2008,32(7)
The reaction cross section of ~(17)B on ~(12)C target at(43.7±2.4)MeV/u has been measured at the Radioactive Ion Beam Line in Lanzhou(RIBLL).The root-mean-square matter radius(R_(rms))was deduced to be(2.92±0.10)fm,while the R_(rms)of the core and the valence neutron distribution are 2.28 fm and 5.98 fm respectively.Assuming a"core plus 2n"structure in ~(17)B,the mixed configuration of(2s_(1/2))and(1d_(1/2))of the valence neutrons is studied and the s-wave spectroscopic factor is found to be(80±21)%. 相似文献
3.
JU Guo-Xing XIANG Yang REN Zhong-Zhou 《理论物理通讯》2006,46(5):819-825
The properties of the 8-wave for a quasl-free partide with position-dependent mass (PDM) have been discussed in details. Differed from the system with constant mass in which the localization of the s-wave for the free quantum particle around the origin only occurs in two dimensions, the quasi-free particle with PDM can experience attractive forces in D dimensions except D = 1 when its mass function satisfies some conditions. The effective mass of a particle varying with its position can induce effective interaction, which may be attractive in some cases. The analytical expressions of the eigenfunctions and the corresponding probability densities for the 8-waves of the two- and three-dimensional systems with a special PDM are given, and the existences of localization around the origin for these systems are shown. 相似文献
4.
采用二带Ginziburg-Landau(G-L)理论模型计算了各向异性超导体的上临界磁场,发现上临界磁场Hc2的解析式中包含序参量的各向异性和有效质量的各向异性;上临界磁场ab-面内分量Hc|2|ab、c-轴方向分量Hc|2|ab与实验数据符合;上临界磁场比率在实验许可范围之内。 相似文献
5.
Josephson current versus potential strength of the interface in ferromagnetic superconductors 下载免费PDF全文
Hamidreza Emamipour 《中国物理 B》2014,(5):541-545
Based on the scattering theory, we calculate the Josephson current in a junction between two ferromagnetic superconductors as a function of the interface potential z. We consider the ferromagnetic superconductor(FS) in three different Cooper pairing states: spin singlet s-wave pairing(SWP) state, spin triplet opposite spin pairing(OSP) state, and spin triplet equal spin pairing(ESP) state. We find that the critical Josephson current as a function of z shows clear differences among the SWP, OSP, and ESP states. The obtained results can be used as a useful tool for determining the pair symmetry of the ferromagnetic superconductors. 相似文献
6.
V. Hankevych F. Wegner 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(3):333-342
We present a stability analysis of the 2D t
-
t' Hubbard model on a square lattice for various values of the next-nearest-neighbor hopping t' and electron concentration. Using the free energy expression, derived by means of the flow equations method, we have performed
numerical calculation for the various representations under the point group C
4ν
in order to determine at which temperature symmetry broken phases become more favorable than the symmetric phase. A surprisingly
large number of phases has been observed. Some of them have an order parameter with many nodes in -space. Commonly discussed types of order found by us are antiferromagnetism, d
x2 - y2
-wave singlet superconductivity, d-wave Pomeranchuk instability and flux phase. A few instabilities newly observed are a triplet analog of the flux phase, a
particle-hole instability of p-type symmetry in the triplet channel which gives rise to a phase of magnetic currents, an s*-magnetic phase, a g-wave Pomeranchuk instability and the band splitting phase with p-wave character. Other weaker instabilities are found also. A comparison with experiments is made.
Received 25 July 2002 / Received in final form 28 November 2002 Published online 14 February 2003
RID="a"
ID="a"Current address: Département de physique and Centre de recherche sur les propriétés électroniques de matériaux avancés, Université de Sherbrooke,
Sherbrooke, Québec, Canada J1K 2R1 e-mail: vaha@physique.usherb.ca 相似文献
7.
JU Guo-Xing XIANG Yang REN Zhong-Zhou 《理论物理通讯》2006,46(11)
The properties of the s-wave for a quasi-free particle with position-dependent mass (PDM) have been discussed in details. Differed from the system with constant mass in which the localization of the s-wave for the free quantum particle around the origin only occurs in two dimensions, the quasi-free particle with PDM can experience attractive forces in D dimensions except D=1 when its mass function satisfies some conditions. The effective mass of a particle varying with its position can induce effective interaction, which may be attractive in some cases. The analytical expressions of the eigenfunctions and the corresponding probability densities for the s-waves of the two- and three-dimensional systems with a special PDM are given, and the existences of localization around the origin for these systems are shown. 相似文献
8.
I. Tornes D. Stroud 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(4):485-493
A zigzag boundary between a $d_{x^2 - y^2}$ and an s-wave
superconductor is believed to behave like a long Josephson junction
with alternating sections of 0 and π symmetry. We calculate the
field-dependent critical current of such a junction, using a simple
model. The calculation involves discretizing the partial differential
equation for the phase difference across a long 0-π junction. In this form, the equations describe a hybrid ladder of inductively
coupled small 0 and π resistively and capacitively shunted Josephson junctions (RCSJ's). The calculated critical critical
current density
Jc(Ha) is maximum at non-zero applied magnetic field Ha, and
depends strongly on the ratio of Josephson penetration depth
λJ to facet length Lf. If λJ/Lf ≫1 and the
number of facets is large, there is a broad range of Ha where
Jc(Ha) is less than 2% of the maximum critical current density
of a long 0 junction. All of these features are in qualitative
agreement with recent experiments. In the limit λJ/Lf
→∞, our model reduces to a previously-obtained
analytical superposition result for Jc(Ha). In the same limit, we
also obtain an analytical expression for the effective field-dependent
quality factor QJ(Ha), finding that
. We suggest that measuring the field-dependence of QJ(Ha) would provide further evidence that this RCSJ model applies to a long 0-π junction between a d-wave and an s-wave superconductor. 相似文献
9.
P. Thalmeier 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(1):29-48
The Heavy Fermion state in UPd2Al3 may be approximately described by a dual model where two of the three U-5
f electrons are in a localized state split by the crystalline electric field into two low lying singlets with a splitting energy
Δ≃ 6 meV. The third 5
f electron has itinerant character and forms the Heavy Electron bands. Inelastic neutron scattering and tunneling experiments
suggest that magnetic excitons, the collective propagating crystal field excitations of the localized 5
f electrons, mediate superconducting (sc) pairing in UPd2Al3. A theory for this novel mechanism is developed within a nonretarded approach. A model for the magnetic exciton bands is
analyzed and compared with experiment. The sc pair potential which they mediate is derived and the gap equations are solved.
It is shown that this mechanism favors an odd parity state which is nondegenerate due to the combined symmetry breaking by
the crystalline electric field and the AF order parameter. A hybrid model including the spin fluctuation contribution to the
pairing is also discussed.
Received 22 October 2001 and Received in final form 28 February 2002 相似文献
10.
N. Andrenacci M. Capezzali H. Beck 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(4):417-432
In order to obtain information about the internal structure of fluctuating Cooper pairs in the pseudogap state and below the
transition temperature of high Tc superconductors, we solve
the Bethe-Salpeter equation for the two-electron propagator in order to calculate a “pair structure function”
that depends on the internal distance
between the partners and on the center of mass momentum P of the pair. We use an attractive Hubbard model with a local potential
for s-wave and a separable potential for d-wave symmetry. The amplitude of gP for small ρ depends on temperature, chemical potential and interaction symmetry, but the ρ dependence itself is rather insensitive
to the interaction strength. Asymptotically gP decreases as an inverse power of ρ for weak coupling, but exponentially when a pseudogap develops for stronger interaction.
Some possibilities of observing the pair structure experimentally are mentioned. 相似文献