Dynamic magnetism of an itinerant-electron antiferromagnet as an internal Josephson effect

The itinerant-electron antiferromagnet is a condensate of electron-hole pairs which have pair spin S=1. In chromium, the order parameter is a sinusoidal wave with spin polarisation in a single direction. This means that two equal-spin-pairing states occur with S z =+or-1, and the S z =0 state is missing. This corresponds to the Anderson-Brinkman-Morel state believed to describe the A phase condensate of helium three. It is shown that the dynamic magnetism of an itinerant-electron antiferromagnet such as chromium can be expressed in a formalism identical to the one used by Leggett for the condensed phases of helium three. Antiferromagnetic resonances of an itinerant-electron antiferromagnet are the same as the 'internal Josephson effect' in helium three discussed by Leggett, Maki and Tsuneto (1974), and others.