Spin superfluidity on the spherical surface

Spintronics on flat surfaces has been investigated over the years, and the scenario is relatively well-known; however, there is a lack of information when considering non-flat geometries. In this paper, we are interested in the spin current on the spherical surface of a ferromagnetic insulator. We are mainly concerned with the superfluid spin current transport when spin current is injected at the north pole and propagates to the south pole. We evaluate the spin transport over the spherical surface using the magnetoelectric circuit theory and the semiclassical magnetization formalism. Including the magnetization damping by the Landau–Lifshitz–Gilbert equation, we obtain a spin current that propagates over distances larger than the magnon ballistic decay length, evidence of spin superfluidity . In addition, provided that the ejected spin current is always radially aligned, along with the dissipationless nature, a spherical shell could be used as an efficient oriented spin valve.