title: Importance of in-plane anisotropy in the quasi-two-dimensional antiferromagnet BaNi2V2O8.
abstract: The phase diagram of the quasi-two-dimensional antiferromagnet BaNi(2)V(2)O(8) is studied by specific heat, thermal expansion, magnetostriction, and magnetization for magnetic fields applied perpendicular to c. At micro(o)H* approximately 1.5 T, a crossover to a high-field state, where T(N)(H) increases linearly, arises from a competition of intrinsic and field-induced in-plane anisotropies. The pressure dependences of T(N) and H* are interpreted using the picture of a pressure-induced in-plane anisotropy. Even at zero field and ambient pressure, in-plane anisotropy cannot be neglected, which implies deviations from pure Berezinskii-Kosterlitz-Thouless behavior.
authors.affiliation: Forschungszentrum Karlsruhe, Institut für Festkörperphysik, D-76021 Karlsruhe, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Knafo
authors.forename: C
authors.initials: C
authors.lastname: Meingast
authors.forename: K
authors.initials: K
authors.lastname: Grube
authors.forename: S
authors.initials: S
authors.lastname: Drobnik
authors.forename: P
authors.initials: P
authors.lastname: Popovich
authors.forename: P
authors.initials: P
authors.lastname: Schweiss
authors.forename: P
authors.initials: P
authors.lastname: Adelmann
authors.forename: Th
authors.initials: T
authors.lastname: Wolf
authors.forename: H
authors.initials: H
authors.lastname: V Löhneysen