title: Spin nematic and antinematic states in a spin-3/2 isotropic non-Heisenberg magnet.
abstract: The ground state phase diagram of a general isotropic spin-3/2 system with nearest-neighbor exchange is shown to contain unconventionally ordered spin nematic and antinematic states, as well as usual ferro- and antiferromagnetic phases. The two nematic phases have spontaneously broken rotational symmetry characterized by the long-range order of the nematic director u, as well as the broken time-reversal symmetry described by the pseudospin vector σ. Nematic phase differs from antinematic one by the type of ordering in σ vectors (uniform versus staggered). The ferromagnet-nematic and antiferromagnet-antinematic phase boundaries exhibit enhanced Sp(4) symmetry and correspond to the recently studied effective theory for spin-3/2 cold gases. We discuss optical properties and topological defects in the nematic phases.
authors.affiliation: V. I. Vernadskii Taurida National university, Simferopol, Ukraine.
authors.forename: Yu A
authors.initials: YA
authors.lastname: Fridman
authors.forename: O A
authors.initials: OA
authors.lastname: Kosmachev
authors.forename: A K
authors.initials: AK
authors.lastname: Kolezhuk
authors.forename: B A
authors.initials: BA
authors.lastname: Ivanov