共查询到20条相似文献,搜索用时 15 毫秒
1.
DONG Zhengchao 《中国科学G辑(英文版)》2006,49(5)
We study the Zeeman effect on the d-wave superconductor and tunneling spectrum in normal-metal(N)/d-wave superconductor(S) junction by applying a Zeeman magnetic field to the S. It is shown that: (1) the Zeeman magnetic field can lead to the S gap decreasing, and with the increase in Zeeman energy, the superconducting state is changed to the normal state, exhibiting a first-order phase transition; (2) the Zeeman energy difference between the two splitting peaks in the conductance spectrum is equal to2h0 (h0 is the Zeeman energy); (3) both the barrier strength of interface scattering and the temperature can lower the magnitudes of splitting peaks, of which the barrier strength can lead to the splitting peaks becoming sharp and the temperature can smear out the peaks,however, neither of them can influence the Zeeman effect. 相似文献
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在超导中通过外加塞曼磁场,研究正常金属/超导/正常金属双隧道结中的量子相干输运。同时考虑从一个正常金属电极注入一电子,从另一个正常金属电极注入一空穴,推导出系统的微分电导的一般公式。研究表明,电导谱随偏压展示振荡行为,随着温度和磁场的增大,其振荡振幅被降低,且塞曼能可导致电导峰的塞曼劈裂。在隧道极限下,超导体中会形成一系列束缚态。 相似文献
4.
Z.C. Dong 《Solid State Communications》2007,142(10):577-582
We solve a self-consistent equation for the d-wave superconducting gap and the magnetization in the mean-field approximation, study the Zeeman effects on the thermodynamic potential of d-wave superconductor (S) and coherent quantum transport in normal-metal (N)/d-wave S/N double tunnel junctions. Taking simultaneously into account the electron-injected current from one N electrode and the hole-injected current from the other N electrode, we derive a general formula for the differential conductance in a N/d-wave S/N system under a Zeeman magnetic field on the d-wave S. It is found that oscillations of all quasiparticle transport coefficients and differential conductance with the bias voltage and the thickness of the d-wave S depend to a great extent on the crystal orientation of the d-wave S. In the N/d-wave S/N junctions, the Zeeman magnetic field can lead to the Zeeman splitting of conductance peaks, and the temperature can reduce the coherent effect. 相似文献
5.
A theoretical study of the fluctuation conductivity above Tc (paraconductivity) is reported for a d-wave superconductor with resonant scattering impurities. A d-wave system is modeled by tight-binding electrons in the two-dimensional squared lattice, and the impurity scattering is treated in the T-matrix approximation in a unitary limit. In calculating the Aslamazov–Larkin (AL) and the Maki–Thompson (MT) terms, we also consider effects of a short-wavelength cutoff in the fluctuation spectrum. The d-wave character in the AL and MT terms manifests itself to renormalization effects on the fluctuation amplitude and reduced temperature, whereas an anomalous-MT term is absent. The present calculations can describe fairly well experiments on the paraconductivity in zinc-doped cuprate superconductors provided that effects of a total-energy cutoff are taken into account. 相似文献
6.
Taking into account the effects of quantum interference and interface scattering, combining the electron current with hole current contribution to tunnel current,we study the coherent quantum transport in normal-metal/d-wave superconductor/normal-metal (NM/d-wave SC/NM) double tunnel junctions by using extended Blonder-Tinkham-Klapwijk (BTK) approach. It is shown that all quasiparticle transport coefficients and conductance spectrum exhibit oscillating behavior with the energy, in which periodic vanishing of Andreev reflection (AR) above superconducting gap is found.In tunnel limit for the interface scattering strength taken very large, there are a series of bound states of quasiparticles formed in SC. 相似文献
7.
Zeeman effects on Josephson current in d-wave superconductor/d-wave superconductor junctions 下载免费PDF全文
This paper solves a self-consistent equation for the d-wave
superconducting gap and the effective exchange field in the
mean-field approximation, and studies the Zeeman effects on the
d-wave superconducting gap and thermodynamic potential. The Josephson
currents in the d-wave superconductor(S)/insulating layer(I)/d-wave S
junctions are calculated as a function of the temperature, exchange
field, and insulating barrier strength under a Zeeman magnetic field
on the two d-wave Ss. It is found that the Josephson critical
currents in d-wave S/d-wave S junction to a great extent depend on
the relative orientation of the effective exchange field of the two S
electrodes, and the crystal orientation of the d-wave S. The exchange
field under certain conditions can enhance the Josephson critical
current in a d-wave S/I/d-wave S junction. 相似文献
8.
通过求解Bogoliubov-de Gennes(BdG)方程,利用推广的Blonder-Tinkham-Klapwijk(BTK)理 论,计算了考虑结界面粗糙散射情况下正常金属-绝缘层-铁磁超导结(N/I/FS)的微分电导 .研究表明,铁磁超导态中的磁交换能Eh能使微分电导峰产生Zeeman劈裂, 劈裂峰的 能量间隔为2Eh,结界面势垒散射和结界面粗糙散射降低了隧道结的微分电导峰 值.
关键词:
N/I/FS超导结
铁磁超导共存态
微分电导
Zeeman劈裂 相似文献
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The Josephson effects in the ferromagnetic superconductor junctions of the equal spin pairing symmetry are investigated by a Furusaki–Tsukada-like formula. It is shown that the internal phase difference between the two different anisotropic superconductors plays an important role on the Josephson current. The current is predicted to be an oscillation function of the macroscopic phase difference with the period 2π, π, or π/2 depending on the different orbital pairing symmetries of the superconductors of the junction. 相似文献
10.
用扫描隧道显微镜/谱仪仔细研究了铁基超导单晶FeSe0.5Te0.5样品的表面形貌和隧道谱, 测量到了清晰的表面原子形貌和在空间比较稳定的隧道谱结构.在样品中测量的隧道谱零能态密度比较高, 说明样品里面有比较强的非弹性准粒子散射. 在正能5 mV附近有个较大的背景鼓包, 这一背景在很高温度也未消失. 空间中Se和Te集中的位置会带来高能背景的变化, 超导能隙附近谱的形状大致相同. 较强的非弹性准粒子散射破坏了超导的准粒子散射, 因此没有在二维微分电导图中发现超导准粒子相干散射的特征亮斑. 相似文献
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Differential conductance in normal-metal/insulator/metal/d-wave superconductor junction carrying a supercurrent 下载免费PDF全文
This paper applies the Bogoliubov--de Gennes equation and
the Blonder--Tinkham--Klapwijk approach to study the oscillatory
behaviour of differential conductance in a normal metal/insulator/metal/d-wave
superconductor junction carrying a
supercurrent Is. We find that (i) a three-humped structure
appears at a nearly critical supercurrent Is and z ≈
0.5 for the normal metal/insulator/metal/d_x2 + y2-wave
superconductor junction; (ii) the zero-bias conductance peak splits
into two peaks with sufficiently large applied current for the normal
metal/insulator/metal/dxy-wave superconductor junction; (iii)
the conductance spectrum exhibits oscillating behaviour with the
bias voltage and the peaks of the resonances are suppressed by
increasing supercurrent Is. 相似文献
13.
Tunneling conductance in quantum wire/insulator/dx2 -y2 + idxy mixed wave superconductor junctions 下载免费PDF全文
Using the extended Blonder-Tinkham-Klapwijk (BTK) theory, this paper calculates the tunnelling conductance in quantum wire/insulator/dx2-y2 + idxy mixed wave superconductor (q/I/dx2-y2 + idxy) junctions. That is different from the case in d- and p-wave superconductor junctions. When the angle α between a-axis of the dx2-y2 wave superconductor and the interface normal is π/4, there follows a rather distinctive tunnelling conductance. The zero-bias conductance peak (ZBCP) may or may not appear in the tunnelling conductance. Both the interface potential z and the quasi-particle lifetime factor Γ are smaller, there is no ZBCP. Otherwise, the ZBCP will appear. The position of bias conductance peak (BCP) depends strongly on the amplitude ratio of two components for dx2-y2 + idxy mixed wave. The low and narrow ZBCP may coexist with the BCP in the tunnelling conductance. Using those features in the tunnelling conductance of q/I/dx2-y2 + idxy junctions, it can distinguish dx2-y2 + idxy mixed wave superconductor from d- and p-wave one. 相似文献
14.
Taking into account the effects of quantum interference and interface scattering, combining the electron current with hole
current contribution to tunnel current, we study the coherent quantum transport in normal-metal/d-wave superconductor/ normal-metal (NM/d-wave SC/NM) double tunnel junctions by using extended Blonder-Tinkham-Klapwijk (BTK) approach. It is shown that all quasiparticle
transport coefficients and conductance spectrum exhibit oscillating behavior with the energy, in which periodic vanishing
of Andreev reflection (AR) above superconducting gap is found. In tunnel limit for the interface scattering strength taken
very large, there are a series of bound states of quasiparticles formed in SC. 相似文献
15.
We have studied the tunneling conductance in ferromagnet/insulator/p-wave superconductor junctions, taking into account the
rough interface scattering effect. We find that there exist zero-bias conductance peaks and single-minimum structure in tunneling
spectroscopy. As the exchange energy increases, the Andreev reflection is always suppressed and the differential conductance
decreases. The differential conductance depends on the barrier strength and the roughness at the interface.
Supported by the Natural Science Foundation of Jiangsu Higher Education Institutions, China (Grant No. 06KJB140009) 相似文献
16.
用Bogoliubov-de Gennes方程来研究量子线/绝缘层/p波超导体结(q/I/p)中的准粒子输运过程,利用推广的Blonder,Tinkham和Klapwijk模型计算绝对零度和有限温度下q/I/p的一级谐波隧道谱.和量子线/绝缘层/d波超导体结的一级谐波隧道谱不同的是q/I/p的一级谐波隧道谱中存在零偏压电导峰.随着q/I/p中绝缘层的势垒散射增强,q/I/p的一级谐波隧道谱中零偏压电导峰变高. 相似文献
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通过求解磁性d波超导中的能隙与磁交换能的自恰方程,利用推广的Blonder-Tinkham-Klapwijk 理论研究磁性半导体/磁性d波超导结中自旋极化准粒子输运系数与微分电导. 计算表明: 1) 磁性d波超导结中的磁交换能h0可导致零偏压电导峰与能隙电导峰劈裂,劈裂的宽度为2h0;2) 磁性半导体中的磁交换能hFS可使零偏压电导峰劈裂的峰值变低. 而由能隙电导峰劈裂的两个子峰,当两种磁性材料的磁
关键词:
磁性半导体
磁性d波超导体
自旋极化输运 相似文献
19.
M. R. Deshpande J. W. Sleight M. A. Reed R. G. Wheeler R. J. Matyi 《Superlattices and Microstructures》1996,20(4):513-522
Zeeman splitting of the ground state of single impurities in the quantum wells of resonant tunneling heterostructures is reported. We determine the absolute magnitude of the effective magnetic spin splitting factorg* for a single impurity in a 44 Å Al0.27Ga0.73As/GaAs/Al0.27Ga0.73As quantum well to be 0.28±0.02. This system also allows for independent measurement of the electron tunneling rates through the two potential barriers and estimation of the occupation probability of the impurity state in the quantum well. 相似文献
20.
Spontaneous internal field around the non-magnetic impurity in spin-triplet p-wave superconductivity
M. Takigawa M. Ichioka K. Kuroki Y. Tanaka 《Physica E: Low-dimensional Systems and Nanostructures》2005,29(3-4):619
The electronic structure around an impurity in spin triplet p-wave superconductors is investigated by the Bogoliubov–de Gennes theory on a tight-binding model. We calculate the spontaneous current and the local density of states around the impurity and discuss the difference between -wave and -wave superconducting states. 相似文献