Triplet Cooper pairs induced in diffusive s-wave superconductors interfaced with strongly spin-polarized magnetic insulators or half-metallic ferromagnets

Abstract

Interfacing superconductors with strongly spin-polarized magnetic materials opens the possibility to discover new spintronic devices in which spin-triplet Cooper pairs play a key role. Motivated by the recent derivation of spin-polarized quasiclassical boundary conditions capable of describing such a scenario in the diffusive limit, we consider the emergent physics in hybrid structures comprised of a conventional s-wave superconductor (e.g. Nb, Al) and either strongly spin-polarized ferromagnetic insulators (e.g. EuO, GdN) or halfmetallic ferromagnets (e.g. CrO2, LCMO). In contrast to most previous works, we focus on how the superconductor itself is influenced by the proximity effect, and how the generated triplet Cooper pairs manifest themselves in the self-consistently computed density of states (DOS) and the superconducting critical temperature Tc. We provide a comprehensive treatment of how the superconductor and its properties are affected by the triplet pairs, demonstrating that our theory can reproduce the recent observation of an unusually large zero-energy peak in a superconductor interfaced with a half-metal, which even exceeds the normal-state DOS. We also discuss the recent observation of a large superconducting spin-valve effect with a Tc change ~1K in superconductor/half-metal structures, in which case our results indicate that the experiment cannot be explained fully by a long-ranged triplet proximity effect.

16 pages, 11 figures, published version

References in corpus (10)

• A spin triplet supercurrent through the half-metallic ferromagnet CrO2
• Nonlocal Thermoelectric Effects and Nonlocal Onsager Relations in a Three-Terminal Proximity-Coupled Superconductor-Ferromagnet Device
• Signature of magnetic-dependent gapless odd frequency states at superconductor/ferromagnet interfaces
• Spin-dependent Cooper Pair Phase and Pure Spin Supercurrents in Strongly Polarized Ferromagnets
• Manifestation of the odd-frequency spin-triplet pairing state in diffusive ferromagnet / superconductor junctions
• Odd Triplet Pairing in clean Superconductor/Ferromagnet heterostructures
• Pairing symmetry conversion by spin-active interfaces in superconducting junctions
• Half-Metallic Superconducting Triplet Spin Valve
• Is CrO${}_2$ Fully Spin-Polarized? - Analysis of Andreev Spectra and Excess Current
• An introduction to the quasiclassical theory of superconductivity for diffusive proximity-coupled systems

Cited by in corpus (27)

• Creation of equal-spin triplet superconductivity at the Al/EuS interface
• Spin splitting induced in a superconductor by an antiferromagnetic insulator
• Quasiclassical theory of superconducting spin-splitter effects and spin-filtering via altermagnets
• Superconducting proximity effect and long-ranged triplets in dirty metallic antiferromagnets
• Voltage-induced thin-film superconductivity in high magnetic fields
• Spin Transport in Half-Metallic Ferromagnet-Superconductor Junctions
• Current cross-correlations and waiting time distributions in Andreev transport through Cooper pair splitters based on triple quantum dots
• Dynamics of two ferromagnetic insulators coupled by superconducting spin current
• The inverse proximity effect in strong ferromagnet-superconductor structures
• Increasing the performance of the superconducting spin valve using a Heusler alloy
• Quasiclassical theory for antiferromagnetic metals
• Spin-flip Enhanced Thermoelectricity in Superconductor-Ferromagnet Bilayers
• Spin-switch Josephson junctions with magnetically tunable $\sin (\delta \phi /n)$ shape
• Observation of magnetic state dependent thermoelectricity in superconducting spin valves
• Signatures of superconducting triplet pairing in Ni--Ga-bilayer junctions
• Crossover between standard and inverse spin-valve effect in atomically thin superconductor/half-metal structures
• Theory of quantum-geometric charge and spin Josephson diode effects in strongly spin-polarized hybrid structures with noncoplanar spin textures
• Magnetically stable zero-bias anomaly in Andreev contact to the magnetic Weyl semimetal Co${}_3$Sn${}_2$S${}_2$
• Voltage control of superconducting exchange interaction and anomalous Josephson effect
• Complete magnetic control over the superconducting thermoelectric effect
• Superconducting Vortices in Half-Metals
• Spin-resolved Josephson diode effect through strongly spin-polarized conical magnets
• Yu-Shiba-Rusinov bands in superconductors in contact with a magnetic insulator
• Supercurrent from the imaginary part of the Andreev levels in non-Hermitian Josephson junctions
• Spin-orbit pumping
• Inverse proximity effect in thin-film superconductor/magnet heterostructures with metallic and insulating magnets
• Density of states in the heterostructure ferromagnetic insulator-superconductor-ferromagnetic insulator