A spin triplet supercurrent through the half-metallic ferromagnet CrO2

Under most conditions, conventional superconductivity and ferromagnetism are mutually exclusive. Although they have been observed together in iron under pressure, the principle holds as a rule. But now Keizer et al. describe a system in which superconductivity and magnetism are finally seen working together. The material in which this occurs is chromium dioxide, well known as the active component of magnetic recording tape. It's a half-metallic ferromagnet, and can sustain a Josephson (or ‘spin triplet’) supercurrent that switches with the direction of magnetization.