Critical current of a Josephson junction containing a conical magnet

G.B Halasz, J.W.A Robinson, J.F Annett, M.G Blamire

Research output: Contribution to journalArticle (Academic Journal)peer-review

34 Citations (Scopus)


We calculate the critical current of a superconductor/ferromagnetic/superconductor (S/FM/S) Josephson junction in which the FM layer has a weakened conical magnetic structure composed of an in-plane rotating antiferromagnetic phase and an out-of-plane ferromagnetic component. In view of the realistic electronic properties and magnetic structures that can be formed when conical magnets such as Ho are grown with a polycrystalline structure in thin-film form by methods such as direct current sputtering and evaporation, we have modeled this situation in the dirty limit with a large magnetic coherence length (ξf). This means that the electron mean free path is much smaller than the normalized spiral length λ/2π which in turn is much smaller than ξf (with λ as the length a complete spiral makes along the growth direction of the FM). In this physically reasonable limit we have employed the linearized Usadel equations: we find that the triplet correlations are short ranged and manifested in the critical current as a rapid oscillation on the scale of λ/2π. These rapid oscillations in the critical current are superimposed on a slower oscillation which is related to the singlet correlations. Both oscillations decay on the scale of ξf. We derive an analytical solution and also describe a computational method for obtaining the critical current as a function of the conical magnetic layer thickness.
Translated title of the contributionCritical current of a Josephson junction containing a conical magnet
Original languageEnglish
Article number224505
Pages (from-to)1-9
Number of pages9
JournalPhysical Review B: Condensed Matter and Materials Physics
Issue number22
Publication statusPublished - Jun 2009

Bibliographical note

Publisher: The American Physical Society

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