Ferromagnetism and high Tc superconductivity

Abstract The analogy between magnetism and superconductivity is important for our understanding of both the phenomena in an unified way. The age-old dilemma between Stoner versus non-Stoner ferromagnetism also exists in high T c superconductors. Between the Bloch-wall stiffness and superconducting phase stiffness the analogy is rigorous and complete. Holes in d-band usher in ferromagnetism; the high T c superconductivity in the copper oxide materials is also heralded by the ubiquitous d-holes—is that fortuitious?