Periodic Co/Nb pseudo spin-valve for cryogenic memory

Abstract

We present a new study of magnetic structures with controllable effective exchange energy for Josephson switches and memory. As a basis for a weak link we propose to use a periodic structure comprised of ferromagnetic (F) layers spaced by thin superconductors (s). Our calculations based on Usadel equations show that switching from parallel (P) to antiparallel (AP) alignment of neighboring F layers can lead to a significant enhancement of the critical current through the junction. To control magnetic alignment we propose to use periodic system where unit cell is a pseudo spin-valve $F_1$/s/$F_2$/s with $F_1$ and $F_2$ two magnetic layers having different coercive fields. In order to check feasibility of controllable switching between AP and P states through the \emph{whole} periodic structure we prepared a superlattice [Co(1.5nm)/Nb(8nm)/Co(2.5nm)/Nb(8nm)]${}_6$ between two superconducting layers of Nb(25nm). Neutron scattering showed that parallel and antiparallel alignment can be organized by using of magnetic fields of only several tens of Oersted.

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Cited by in corpus (8)

• Magnetic proximity effect in [Nb/Gd] superlattices seen by neutron scattering
• Crossover between short and long range proximity effects in SFS junctions with Ni-based ferromagnets
• Proximity effect in [Nb(1.5nm)/Fe(x)]${}_{10}$/Nb(50nm) superconducting/ferromagnet heterostructures
• Modelling the processes of atom structure formation of a superconducting spin valve
• The physics of superconductor-ferromagnet hybrid structures
• Dynamic properties of asymmetric double Josephson junction stack with quasiparticle imbalance
• Transport characterization of magnetic states in Superconductor/Ferromagnet Nb/Co multilayers
• In situ transport characterization of magnetic states in Nb/Co superconductor/ferromagnet heterostructures