title: Ferromagnetism in doped excitonic insulators
abstract: The theory of doped excitonic insulators is reinvestigated in light of recent experiments on hexaborides. For the appropriate valley-degenerate X3,X'3 band structure, "intravalley" condensation is energetically favored. Ferromagnetism occurs upon doping due to the quenching of kinetic energy at the otherwise direct first-order excitonic insulator-metal transition. The phase diagram includes states of spatially inhomogeneous density and magnetization at low temperatures.
authors.affiliation: Room 1D-368, Bell Laboratories, Lucent Technologies, 700 Mountain Avenue, Murray Hill, New Jersey 07974, USA.
authors.initials: L
authors.lastname: Balents
authors.initials: CM
authors.lastname: Varma