Ferromagnetism of a gas of hard sphere fermions

Abstract

The energy of a gas of fermions of spin ¹/₂, interacting with a hard sphere repulsion, is obtained by means of Brueckner's approach to the many-body problem. The single particle potential is computed in the effective mass approximation, and the value of the maximum density for which this approximation is valid, is derived. By means of a modification of the effective mass approximation, in which the effective mass becomes spin-dependent, it is shown that above a certain critical density, the gas becomes ferromagnetic.