Supergap and subgap enhanced currents in asymmetric {S_1FS_2} Josephson junctions

Abstract

We have theoretically studied the supercurrent profiles in three-dimensional normal metal and ferromagnetic Josephson configurations, where the magnitude of the superconducting gaps in the superconducting leads are unequal, i.e., ${\Delta }_1\ne {\Delta }_2$, creating asymmetric $S_{1}N{S}_2$ and $S_{1}F{S}_2$ systems. Our results reveal that by increasing the ratio of the superconducting gaps ${\Delta }_2/{\Delta }_1$, the critical supercurrent in a ballistic $S_{1}N{S}_2$ system can be enhanced by more than $100\%$, and reaches a saturation point, or decays away, depending on the junction thickness, magnetization strength, and chemical potential. The total critical current in a diffusive $S_{1}N{S}_2$ system was found to be enhanced by more than $50\%$ parabolically, and reaches saturation by increasing one of the superconducting gaps. In a uniform ferromagnetic junction, the supercurrent undergoes reversal by increasing ${\Delta }_2/{\Delta }_1>1$. Through decomposing the total supercurrent into its supergap and subgap components, our results illustrate their crucial relative contributions to the Josephson current flow. It was found that the competition of subgap and supergap currents in a $S_{1}F{S}_2$ junction results in the emergence of second harmonics in the current-phase relation. In contrast to a diffusive asymmetric Josephson configuration, the behavior of the supercurrent in a ballistic system with ${\Delta }_2/{\Delta }_1=1$ can be properly described by the subgap current component only, in a wide range of parameter sets, including Fermi level mismatch, magnetization strength, and junction thickness. Interestingly, when ${\Delta }_2/{\Delta }_1>1$, our results have found multiple parameter sets where the total supercurrent is driven by the supergap component. Therefore, our comprehensive study highlights the importance of subgap and supergap supercurrent components in both the ballistic and diffusive regimes.

arXiv comment18 pages, 16 figures

References in corpus (46)

• Coupling of two superconductors through a ferromagnet : evidence for a pi-junction
• Transport in two-dimensional topological materials: recent developments in experiment and theory
• Josephson effect due to the long-range odd-frequency triplet superconductivity in SFS junctions with Neel domain walls
• Josephson effect in double-barrier superconductor-ferromagnet junctions
• Observation of Periodic pi-Phase Shifts in Ferromagnet-Superconductor Multilayers
• Proximity effects at ferromagnet-superconductor interfaces
• Josephson Junction through a Disordered Topological Insulator with Helical Magnetization
• Critical current in SFIFS junctions
• Half-Metallic Superconducting Triplet Spin Valve
• Proximity effects and characteristic lengths in ferromagnet-superconductor structures
• Zero Energy Peak and Triplet Correlations in Nanoscale SFF Spin-Valves
• Layered ferromagnet-superconductor structures: the $\pi$ state and proximity effects
• Spontaneous Edge Accumulation of Spin Currents in Finite-Size Two-Dimensional Diffusive Spin-Orbit Coupled SFS Heterostructures
• Spontaneous supercurrent and $\varphi$0 phase shift parallel to magnetized topological insulator interfaces
• Magnetization-control and transfer of spin-polarized Cooper pairs into a half-metal manganite
• Strain-engineered Majorana Zero Energy Modes and ϕ0 Josephson State in Black Phosphorus
• Charge and Spin Currents in Ferromagnetic Josephson junctions
• Topological superconductivity in planar Josephson junctions: Narrowing down to the nanowire limit
• Long-Range Spin-Triplet Correlations and Edge Spin Currents in Diffusive Spin-Orbit Coupled SNS Hybrids with a Single Spin-Active Interface
• Half-Metallic Superconducting Triplet Spin MultiValves
• Critical supercurrent and ${\varphi }_0$ state for probing a persistent spin helix
• Josephson Currents and Spin Transfer Torques in Ballistic SFSFS Nanojunctions
• Proximity Induced Vortices and Long-Range Triplet Supercurrents in Ferromagnetic Josephson Junctions and Spin Valves
• Spin-transport in superconductors
• Fraunhofer response and supercurrent spin switching in black phosphorus with strain and disorder
• Spin supercurrent in Josephson contacts with noncollinear ferromagnets
• Self-biased current, magnetic interference response, and superconducting vortices in tilted Weyl semimetals with disorder
• Enhanced spin-triplet pairing in magnetic junctions with s-wave superconductors
• Josephson junctions of Weyl and multi-Weyl semimetals
• Analytical criteria for magnetization reversal in ${\phi }_0$ Josephson junction
• Evolution of Pair Correlation Symmetries and Supercurrent Reversal in Tilted Weyl Semimetals
• Stability of $\pi$ junction configurations in ferromagnet-superconductor heterostructures
• Spin Transport in Half-Metallic Ferromagnet-Superconductor Junctions
• Competitive 0 and π states in S/F multilayers: multimode approach
• Observation of the dominant spin-triplet supercurrent in Josephson spin valves with strong Ni ferromagnets
• Anomalous Josephson Hall effect charge and transverse spin currents in superconductor/ferromagnetic insulator/superconductor junctions
• Magnetization Reversal by Tuning Rashba Spin-Orbit Interaction and Josephson Phase in a Ferromagnetic Josephson Junction
• Energy gap of ferromagnet-superconductor bilayers
• Anomalous current-voltage characteristics of SFIFS Josephson junctions with weak ferromagnetic interlayers
• Josephson current through a ferromagnetic bilayer: Beyond the quasiclassical approximation
• Spin-split conductance and subgap peak in ferromagnet/superconductor spin valve heterostructures
• Local Density of States and Order Parameter Configurations in Layered Ferromagnet-Superconductor Structures
• Spin transport and Spin Tunnelling Magneto-Resistance (STMR) of F$|$NCSC$|$F spin valve
• Quasiparticle conductance in Spin Valve Josephson Structures
• The long-range spin-singlet proximity effect for the Josephson system with single-crystal ferromagnet due to its band structure features
• Dynamic properties of asymmetric double Josephson junction stack with quasiparticle imbalance

Cited by in corpus (5)

• Cubic spin-orbit coupling and anomalous Josephson effect in planar junctions
• Supercurrent Diode Effect, Spin Torques, and Robust Zero-Energy Peak in Planar Half-Metallic Trilayers
• Supercurrent decay in ballistic magnetic Josephson junctions
• Signatures of superconducting triplet pairing in Ni--Ga-bilayer junctions
• Chiral Josephson effect in double layers: the role of particle-hole duality