title: Itinerant half-metal spin-density-wave state on the hexagonal lattice.
abstract: We consider electrons on a honeycomb or triangular lattice doped to the saddle point of the band structure. We assume the system parameters are such that spin density wave (SDW) order emerges below a temperature T(N) and investigate the nature of the SDW phase. We argue that at T≤T(N), the system develops a uniaxial SDW phase whose ordering pattern breaks O(3)×Z(4) symmetry and corresponds to an eight-site unit cell with nonuniform spin moments on different sites. This state is a half-metal--it preserves the full original Fermi surface, but has gapless charged excitations in one spin branch only. It allows for electrical control of spin currents and is desirable for nanoscience.
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Rahul
authors.initials: R
authors.lastname: Nandkishore
authors.forename: Gia-Wei
authors.initials: GW
authors.lastname: Chern
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Chubukov