Josephson effects in one junction with one s-wave superconductor and two topological superconductors

We present an analysis of Josephson effects in one quantum-dot-embedded junction with one s-wave superconductor (SC) and two topological superconductors (TSs). It is found that when superconducting phase difference is applied between the two TSs, the dot-SC coupling can efficiently modulate the fractional Josephson effect, including the changes of the supercurrent oscillation direction and period. Even though the polarization directions of the TSs are opposite, the dot-SC coupling enables to drive the fractional Josephson effect between the TSs. Next, as the superconducting phase difference is introduced between the TSs and SC, only the normal Josephson effect takes place.

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Josephson effects in the junction formed by DIII-class topological and s-wave superconductors with an embedded quantum dot

Scientific Reports ◽

10.1038/srep28311 ◽

2016 ◽

Vol 6 (1) ◽

Author(s):

Zhen Gao ◽

Xiao-Qi Wang ◽

Wan-Fei Shan ◽

Hai-Na Wu ◽

Wei-Jiang Gong

Keyword(s):

Quantum Dot ◽

Josephson Effects ◽

S Wave

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Josephson effect in junctions of conventional and topological superconductors

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.9.158 ◽

2018 ◽

Vol 9 ◽

pp. 1659-1676 ◽

Cited By ~ 6

Author(s):

Alex Zazunov ◽

Albert Iks ◽

Miguel Alvarado ◽

Alfredo Levy Yeyati ◽

Reinhold Egger

Keyword(s):

Bound States ◽

Josephson Effect ◽

Mean Field ◽

Josephson Current ◽

Field Analysis ◽

Current Phase ◽

Topological Superconductor ◽

Topological Superconductors ◽

Spin Singlet ◽

Hybrid Devices

We present a theoretical analysis of the equilibrium Josephson current-phase relation in hybrid devices made of conventional s-wave spin-singlet superconductors (S) and topological superconductor (TS) wires featuring Majorana end states. Using Green’s function techniques, the topological superconductor is alternatively described by the low-energy continuum limit of a Kitaev chain or by a more microscopic spinful nanowire model. We show that for the simplest S–TS tunnel junction, only the s-wave pairing correlations in a spinful TS nanowire model can generate a Josephson effect. The critical current is much smaller in the topological regime and exhibits a kink-like dependence on the Zeeman field along the wire. When a correlated quantum dot (QD) in the magnetic regime is present in the junction region, however, the Josephson current becomes finite also in the deep topological phase as shown for the cotunneling regime and by a mean-field analysis. Remarkably, we find that the S–QD–TS setup can support φ0-junction behavior, where a finite supercurrent flows at vanishing phase difference. Finally, we also address a multi-terminal S–TS–S geometry, where the TS wire acts as tunable parity switch on the Andreev bound states in a superconducting atomic contact.

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s-Wave holographic superconductor in different ensembles and its thermodynamic consistency

International Journal of Modern Physics D ◽

10.1142/s0218271817500274 ◽

2017 ◽

Vol 26 (04) ◽

pp. 1750027

Author(s):

Lei Yin ◽

Defu Hou

Keyword(s):

Order Parameter ◽

Helmholtz Free Energy ◽

Canonical Ensemble ◽

Landau Theory ◽

Equation Of Motion ◽

Superconducting Phase ◽

S Wave ◽

Holographic Superconductor ◽

Thermodynamic Relation ◽

Ginzburg Landau

In this paper, we analytically study the consistency between the Ginzburg–Landau theory of the holographic superconductor in different ensembles and the fundamental thermodynamic relation, we derive the equation of motion of the scalar field which depicts the superconducting phase in canonical ensemble (CE) and a consistent formula to connect the holographic order-parameter to the Ginzburg–Landau coefficients in different thermodynamic ensembles, and we also study the spatially nonuniform Helmholtz free energy.

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NONEQUILIBRIUM THERMODYNAMICS OF JOSEPHSON DEVICES

Modern Physics Letters B ◽

10.1142/s0217984996001024 ◽

1996 ◽

Vol 10 (19) ◽

pp. 903-908

Author(s):

ALEC MAASSEN VAN DEN BRINK ◽

H. DEKKER

Keyword(s):

Phase Difference ◽

Nonequilibrium Thermodynamics ◽

Superconducting Phase ◽

Josephson Coupling ◽

Detailed Calculation ◽

Superconducting Transition ◽

Tunneling Junction ◽

Josephson Devices ◽

First Order ◽

A Value

The rapid increase of the Josephson free energy as the temperature of a tunneling junction drops below the superconducting transition temperature T c is shown to make this transition of first order in a system in which the phase difference ϕ across the junction is constrained to have a nonzero value. Taking this effect into account, we introduce an availability potential governing the nonisothermal dynamics of the junction which, in contrast with previous results, has no artifacts like latent heat being released upon entering the — high temperature — normal state or a value in this state which depends on the — superconducting — phase difference. The thermodynamic analysis is preceded by a detailed calculation of the Josephson coupling in a model of two ideal BCS superconductors coupled by a tunneling Hamiltonian.

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Upper Critical Field in Electron-Doped Superconductor with Nonstoichiometric Disorder near Antiferromagnetic-Superconducting Phase Boundary

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.215.77 ◽

2014 ◽

Vol 215 ◽

pp. 77-82 ◽

Cited By ~ 5

Author(s):

Tatiana B. Charikova ◽

Nina G. Shelushinina ◽

German I. Harus ◽

Denis S. Petukhov ◽

Andrei A. Ivanov

Keyword(s):

Phase Boundary ◽

Critical Field ◽

Upper Critical Field ◽

Superconducting Phase ◽

Spin Fluctuations ◽

S Wave ◽

Optimal Doping ◽

Resistivity Method ◽

Upward Curvature ◽

Disorder Parameter

Using the resistivity method it was found that temperature dependence of the upper critical field for underdoped Nd1.86Ce0.14CuO4+δ have an anomalous upward curvature of Hc2(T) dependence and can be consistently explained by the two-band/two-gap model of a dirty superconductor. Near antiferromagnetic-superconducting phase boundary the critical temperature remains constant with the change of the disorder parameter and the slope of Bc2 increases with increasing of the disorder parameter. This behavior is completely different from dependencies for pure superconducting phase at optimal doping region. This difference may indicate the change of the type of the paring: from the predominance of the anisotropic s-wave component (may be due to unstable competition between antiferromagnetic (AF) and superconducting (SC) regions) in underdoped (x=0.14) region to the prevalence of d-wave part in optimal doped regions (x=0.15) because of residual spin fluctuations.

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