Zeeman effects on Josephson current in d-wave superconductor/d-wave superconductor junctions

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.

Anomalous Transport Characteristics of High Temperature Superconductors and Josephson Currents

The transport characteristics of high temperature superconductor current and Josephson current is inves-tigated in the framework of the modified time-dependent Ginzburg-Landau model and the Lawrence-Doniach model.We evaluated the vortex equation and found that the signs of the high temperature superconductor current and theJosephson current can reverse. Some explicit expressions for different cases are derived, which accord with experimentaldata.

Anomalous Josephson current in quantum anomalous Hall insulator-based superconducting junctions with a domain wall structure

We theoretically study the Josephson effect in a quantum anomalous Hall insulator(QAHI)nanoribbon with a domain wall structure and covered by the superconductor.The anomalous Josephson current,the nonzero supercurrent at the zero superconducting phase difference,appears with the nonzero magnetization and the suitable azimuth angle of the domain wall.Dependent on the configuration of the domain wall,the anomalous current peaks in the Bloch type but disappears in the Néel type because the y-component of magnetization is necessary to break symmetry to arouse the anomalous current.The phase shift of the anomalous current is tunable by the magnetization,the azimuth angle,or the thickness of the domain wall.By introducing a bare QAHI region in the middle of the junction which is not covered by the superconductor,the anomalous Josephson effect is enhanced such that the phase shift can exceedπ.Thus,a continuous change between 0 andπjunctions is realized via regulating the configuration of the domain wall or the magnetization strength.As long as an s-wave superconductor is placed on the top of the QAHI with a domain wall structure,this proposal can be experimentally fabricated and useful for the phase battery or superconducting quantum bit.

Josephson Current in f-Wave Superconductor/f-Wave Superconductor Junctions

We study the temperature T and the phase of the Josephson critical current I（Ф） by taking into account the roughness scattering effect at inerface in an f-wave superconductor （S）/Insulator layer （I）/f-wave superconductor （S） junction. It is found that the Josephson critical currents in f-wave Sir-wave S, the barrier strength and the roughness strength at inerface always suppress the Andreev reflection. When α=β, the phase dependence of the Josephson current I（Ф） between two f-wave S is predicted to be sin Ф; particularly, when a α≠ β, the phase dependence of the Josephson current I（Ф） between two f-wave superconductors is not predicted to be sin Ф and with the barrier strength increasing, the period of the I（Ф） turns decrease.

Energy gap suppression and excess current in TI2Ba2CaCu208 intrinsic Josephson junctions

Intrinsic Josephson junctions in misaligned T12Ba2CaCu208 thin film were fabricated on LaA103 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.

Spontaneous Josephson spin current in triplet superconductor/ferromagnet/triplet superconductor junctions

This paper theoretically studies Josephson spin current through triplet superconductor/ferromagnet/triplet super- conductor junctions. At the ferromagnet/superconductor interfaces, the ferromagnetic scattering potential gives rise to coupling between the Andreev bound states and lifts their spin degeneracy. These spin-split Andreev states carry the Josephson spin current through the junctions. The generated spin supercurrent can be controlled by the magnetization of a ferromagnetic thin layer and bias voltage across the junctions.

Interfacial spin Hall current in a Josephson junction with Rashba spin-orbit coupling

We theoretically investigate the spin transport properties of the Cooper pairs in a conventional Josephson junction with Rashba spin-orbit coupling considered in one of the superconducting leads.It is found that an angle-resolved spin supercurrent flows through the junction and a nonzero interfacial spin Hall current driven by the superconducting phase difference also appears at the interface.The physical origin of this is that the Rashba spin-orbit coupling can induce a triplet order parameter in the s-wave superconductor.The interfacial spin Hall current dependences on the system parameters are also discussed.

Dependence of Switching Current Distribution of a Current-Biased Josephson Junction on Microwave Frequency

We investigate the distribution of the switching current of a current-biased Josephson junction （CBJJ） and its dependence on the microwave frequency using two theoretical methods, one of which is the quantum trajectory method and the other is the master equation method. Both the methods show that the distribution of the switching current of CBJJ will exhibit double peaks in a certain range of microwave frequency if proper microwave power is given, and the gap between the two peaks will increase with the microwave frequency. The obtained results can be used to identify the energy difference of the ground and first excited states in a Josephson junction for any bias current.

Energy gap suppression and excess current in Tl_2Ba_2CaCu_2O_8 intrinsic Josephson junctions

Intrinsic Josephson junctions in misaligned Tl2Ba2CaCu2O8 thin film were fabricated on LaAlO3 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.

s/FI/d超导结的直流Josephson电流

在 s波超导体 /铁磁绝缘层 / d波超导体 Josephson结 (s/ FI/ d)中 ,考虑结界面铁磁绝缘层的磁散射和粗糙散射情况下 ,运用 Bd G方程和 FT的电流公式计算准粒子的输运系数及 s/ FI/ d结的直流 Josephson电流与温度 T、结两侧的相位差之间的关系。研究表明 :结界面的磁散射和粗造散射均抑制结中准粒子的 Andreev反射 ,降低了流过 s/ FI/ d结的直流 Josephson电流 ,直流Josephson电流 I随温度 T、相位差φ的变化曲线强烈地依赖于

用Josephson结电子模拟器测量磁通量子2e/h

介绍用 Josephson结电子模拟器在正常温度下 ,模拟测量磁通量子 2 e/ h,用模拟器来研究 Josephson结的特性 .该实验可作为普通物理实验中课题设计实验的一个内容 .

DSC系统的dc Josephson电流阶梯效应

由Ｊｏｓｅｐｈｓｏｎ关系，得出ＤＳＣ系统分别处于稳恒磁场和交变磁场时，两结间所加交变电压的直流分量改变，将导致系统的ｄｃＪｏｓｅｐｈｓｏｎ电流产生多次阶梯效应．

矩形结在交变磁场中的dc Josephson电流

矩形Ｊｏｓｅｐｈｓｏｎ结处于交变磁场中时，仍有超导量子衍射现象出现，但与结处于恒定磁场中情形有所不同．结区两侧间加上直流偏置电压，仍处于交变磁场中，当２ｅＵ０／ｈ＝－２ｍω０（ｍ＝０，±１，±２，…）时，ｄｃＪｏｓｅｐｈｓｏｎ电流将产生多次阶梯．

Anisotropy of p-wave Josephson junction

The anisotropy of the dc Josephson current in the superconducting junctions of the p-wave equal spin pairing symmetry is theoretically investigated by the Furusaki Tsukada-like formula. The current phase relations exhibit different oscillation periods and different phase shifts for the current along different directions, respectively.

外场中超导体/半导体/超导体结的直流Josephson电流

当外加磁场时,超导体/半导体/超导体结的临界电流受外加磁场的影响.超导结的临界电流与磁场的曲线非常类似于单色光在单狭缝衍射的夫琅和费图样.在未考虑外加磁场的超导体/半导体/超导体结的临界电流的基础上,进一步对外加磁场的情形进行了研究.

dc Josephson Effect in s-Wave Superconductor/Ferromagnet Insulator/p-Wave Superconductor Junctions

The Josephson currents in s-wave superconductor/ferromagnet insulator/p-wave superconductor（s/FI/p） junctions are calculated as a function of temperature and the phase taking into account the roughness scattering effect at interface. The phase dependence of the Josephson current I （φ） between s-wave and px-wave superconductor is predicted to be sin（2φ）. The ferromagnet scattering effect, the barrier strength, and the roughness strength at interface suppress the dc currents in s/FI/p junction.

Josephson Effect in FS/I/N/I/FS Tunnel Junctions

The Bogoliubov de Gennes equation is applied to the study of coherence effects in the ferromagnetic superconductor/insulator/normal metal/insulator/ferromagnetic/superconductor （FS/I/N/I/FS） junction. We calculated the Josephson current in FS/I/N/I/FS as a function of exchange field in ferromagnetic superconductor, temperature, and normal metal thickness. It is found that the Josephson critical current in FS/I/N/I/FS exhibits oscillations as a function of the length of normal metal. The exchange field always suppresses the Josephson critical current Ip for a parallel configuration of the magnetic moments of two ferromagnetic superconductor （FS） electrodes. In the antiparallel configuration, the Josephson critical current IAv at the minimum values of oscillation increases with the exchange field for strong barrier strength and at low temperatures.

SSeS超导结的Josephson效应

以推广了的Jacobson方法 ,由Ginzburg Landau方程出发 ,推导出了SSeS超导结的直流Josephson效应 .从而进一步求得了SSeS超导结的临界电流与温度之间的关系 ,以及对结区厚度的依赖性 .

不对称s波超导体/绝缘层/s波超导体结的直流Josephson电流

在不对称s波超导体/绝缘层/s波超导体Josephson结(s/I/s)中,考虑结界面粗糙散射情况下,运用Bogoliubov deGennes(BdG)方程和Furusaki Tsukada(FT)的电流公式计算准粒子的输运系数及s/I/s结的直流Josephson电流.研究表明,结界面的通常势垒和粗糙散射均抑制结中准粒子的Andreev反射,降低了流过s/I/s结的直流Josephson电流,直流Josephson电流I随温度T的变化关系与结两侧的对称性有关.

Study of Nb/Nb_xSi_(1-x)/Nb Josephson junction arrays

Owing to the adjustable characteristics and superior etching properties of co-sputtered Nbx Si1-x film, we are trying to fabricate Nb/Nbx Si1-x/Nb Josephson junction arrays for voltage standard. It is important to find the suitable Nbx Si1-x barrier for the junctions. Josephson junctions with different barrier content are fabricated. Current–voltage characteristics are measured and analyzed. It is demonstrated in this paper that critical current can be adjusted by using different barrier content and thickness. Shapiro steps of five hundred junctions in series are observed.