Fractional spin Josephson effect and electrically controlled magnetization in quantum spin Hall edges

Qinglei Meng, Vasudha Shivamoggi, Taylor L. Hughes, Matthew J. Gilbert, Smitha Vishveshwara

Research output: Contribution to journalArticle


We explore a spin Josephson effect in a system of two ferromagnets coupled by a tunnel junction formed of two-dimensional (2D) time-reversal invariant topological insulators. In analogy with the more commonly studied instance of the Josephson effect for charge in superconductors, we investigate properties of the phase-coherent spin current resulting from the misalignment of the in-plane magnetization angles of the two ferromagnets. We show that the topological insulating barrier offers the exciting prospect of hosting a fractional spin Josephson effect mediated by bound states at the ferromagnet-topological insulator interface. We provide multiple perspectives to understand the 4π periodic nature of this effect. We discuss several measurable consequences, such as the generation of a transverse voltage signal which allows for purely electrical measurements, an inverse of this effect where an applied voltage gives rise to a transverse spin current, and a fractional ac spin Josephson effect.

Original languageEnglish (US)
Article number165110
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number16
StatePublished - Oct 9 2012


ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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