Tunneling Conductance and Spin Transport in Clean Ferromagnet-Ferromagnet-Superconductor Heterostructures

Abstract

We present a transfer matrix approach that combines the Blonder-Tinkham-Klapwijk (BTK) formalism and self-consistent solutions to the Bogolibuov-de Gennes (BdG) equations and use it to study the tunneling conductance and spin transport in ferromagnet ($\mathrm{F}$)-superconductor ($\mathrm{S}$) trilayers (${\mathrm{F}}_1{\mathrm{F}}_2\mathrm{S}$) as functions of bias voltage. The self-consistency ensures that the spin and charge conservation laws are properly satisfied. We consider forward and angularly averaged conductances over a broad range of the strength of the exchange fields and $\mathrm{F}$ thicknesses, as the relative in-plane magnetization angle, $\varphi$, between the two ferromagnets varies. The $\varphi$-dependence of the self-consistent conductance curves in the trilayers can differ substantially from that obtained via a non-self-consistent approach. The zero bias forward conductance peak exhibits, as $\varphi$ varies, resonance effects intricately associated with particular combinations of the geometrical and material parameters. We find, when the magnetizations are non-collinear, signatures of the anomalous Andreev reflections in the subgap regions of the angularly averaged conductances. When ${\mathrm{F}}_1$ is half-metallic, the angularly averaged subgap conductance chiefly arises from anomalous Andreev reflection. The in-plane components of the spin current are strongly bias dependent, while the out-of-plane spin current component is only weakly dependent upon voltage. The components of the spin current aligned with the local exchange field of one of the F layers are conserved in that layer and in the S region, while they oscillate in the other layer. We compute the spin transfer torques, in connection with the oscillatory behavior of spin currents, and verify that the spin continuity equation is strictly obeyed in our method.

arXiv comment19 pages including figures. To appear in Phys. Rev. B; Fig12 is revised

References in corpus (38)

• Spintronics: Fundamentals and applications
• Proximity effects in superconductor-ferromagnet heterostructures
• Spin Transfer Torques
• Odd Triplet Superconductivity and Related Phenomena in Superconductor-Ferromagnet Structures
• A spin triplet supercurrent through the half-metallic ferromagnet CrO2
• Observation of spin-triplet superconductivity in Co-based Josephson Junctions
• Andreev Reflection In Ferromagnet-Superconductor Junctions
• How to calculate the degree of spin polarization in ferromagnets?
• Triplet supercurrents in clean and disordered half-metallic ferromagnets
• Theory of Half Metal-Superconductor Heterostructures
• Spin current in ferromagnet/insulator/superconductor junctions
• Enhancement of the Josephson current by an exchange field in superconductor-ferromagnet structures
• Evidence for Triplet Superconductivity in a Superconductor-Ferromagnet Spin Valve
• Superconducting triplet spin valve
• Tunneling spectroscopy for ferromagnet/superconductor junctions
• Spin polarized tunneling in ferromagnet/unconventional superconductor junctions
• Odd Triplet Pairing in clean Superconductor/Ferromagnet heterostructures
• Manifestation of triplet superconductivity in superconductor-ferromagnet structures
• Observation of the Triplet Spin-Valve Effect in a Superconductor-Ferromagnet Heterostructure
• Proximity effects at ferromagnet-superconductor interfaces
• Transport spin polarisation in SrRuO3 measured through Point Contact Andreev reflection
• Induced Triplet Pairing in clean s-wave Superconductor/Ferromagnet layered structures
• Proximity effect, quasiparticle transport, and local magnetic moment in ferromagnet-d-wave superconductor junctions
• Crossover from the Josephson effect to bulk superconducting flow
• Angular dependence of superconductivity in superconductor / spin valve heterostructures
• Proximity effects and characteristic lengths in ferromagnet-superconductor structures
• Spin transport and relaxation in superconductors
• Solution of the Bogoliubov-de Gennes equations at zero temperature throughout the BCS-BEC crossover: Josephson and related effects
• Spin-active interfaces and unconventional pairing in half-metal$\mid$superconductor junctions
• Theory of superconductor-ferromagnet point contact spectra: the case of strong spin polarization
• Proximity effects and triplet correlations in Ferromagnet/Ferromagnet/Superconductor nanostructures
• Observation of Andreev bound states at spin-active interfaces
• Emergence of Triplet Correlations in Superconductor/Half Metallic Nanojunctions with Spin Active Interfaces
• Spin-Transfer Torque and Magnetoresistance in Superconducting Spin-Valves
• Self-consistent scattering description of transport in normal-superconductor structures
• Stability of $\pi$ junction configurations in ferromagnet-superconductor heterostructures
• Tunneling conductance in Superconductor/Ferromagnet junctions: a self consistent approach
• Scattering theory of magnetic/superconducting junctions with spin active interfaces

Cited by in corpus (19)

• Charge and Spin Currents in Ferromagnetic Josephson junctions
• Josephson Currents and Spin Transfer Torques in Ballistic SFSFS Nanojunctions
• General framework for transport in spin-orbit-coupled superconducting heterostructures: Nonuniform spin-orbit coupling and spin-orbit-active interfaces
• Magnetoelectric Andreev effect due to proximity-induced non-unitary triplet superconductivity in helical metals
• Enhanced spin-triplet pairing in magnetic junctions with s-wave superconductors
• Spin Transport in Half-Metallic Ferromagnet-Superconductor Junctions
• Transport in Ferromagnet/Superconductor spin valves
• Spin current and spin transfer torque in ferromagnet/superconductor spin valves
• Theory of tunneling spectroscopy of normal metal/ferromagnet/spin-triplet superconductor junctions
• Spin-split conductance and subgap peak in ferromagnet/superconductor spin valve heterostructures
• Superconducting spin valves based on antiferromagnet/superconductor/antiferromagnet heterostructures
• Spin transport and Spin Tunnelling Magneto-Resistance (STMR) of F$|$NCSC$|$F spin valve
• Quasiparticle conductance in Spin Valve Josephson Structures
• Probing the magnetoelectric effect in noncentrosymmetric superconductors by equal-spin Andreev tunneling
• Effect of Rashba spin-orbit coupling, magnetization and mixing of gap parameter on tunnelling conductance in F$|$NCSC junction of an F$|$S$|$F spin valve
• Bias current dependence of superconducting transition temperature in superconducting spin valve nanowires
• Inverse proximity effect in thin-film superconductor/magnet heterostructures with metallic and insulating magnets
• Triplet correlations in superconductor/antiferromagnet heterostructures: dependence on type of antiferromagnetic ordering
• Tunneling conductance in half-metal/conical magnet/superconductor junctions in the adiabatic and non-adiabatic regime: self-consistent calculations