Superfluid ³He A is a liquid ferromagnet

Abstract

THE superfluid A phase of liquid ³He (see for example refs 1, 2) is often said to display orbital ferromagnetism³. This term generally seems to be meant metaphorically and to imply that this phase possesses a finite total orbital angular momentum in equilibrium³. I point out here that superfluid ³He A is in fact quite literally ferromagnetic, with a spontaneous magnetic moment which, although extremely small on the scale of ordinary ferromagnets (∼ 10⁻¹¹ Bohr magnetons per atom) is probably measurable and may indeed have some interesting experimental implications.