Half-Spin Vortices in Superconducting Material...

In most known superconductors, electrons pair up to form spin singlets: combinations of spin up and spin down with zero angular momentum. But in a few materials, including strontium ruthenate (Sr₂RuO₄, or SRO), the electron pairs form spin triplets (see the article by Yoshiteru Maeno, Maurice Rice, and Manfred Sigrist in Physics Today, January 2001, page 42).  In SRO, the triplets are thought to take a form that can be represented as two weakly interacting superfluid condensates: one of spin-up pairs, the other of spin-down pairs. That arrangement can support half-quantum vortices (HQVs), in which one condensate has one more quantum of vorticity than the other. Because of HQVs' potential applications to quantum computing, they’ve been extensively studied by theorists and sought by experimentalists. Now, researchers led by Raffi Budakian (University of Illinois at Urbana-Champaign) have found the first experimental evidence of HQVs in SRO.

Link: Half quantum vortices