title: Magnetoelastic coupling and symmetry breaking in the frustrated antiferromagnet alpha-NaMnO2.
abstract: The magnetic and crystal structures of the alpha-NaMnO2 have been determined by high-resolution neutron powder diffraction. The system maps out a frustrated triangular spin lattice with anisotropic interactions that displays two-dimensional spin correlations below 200 K. Magnetic frustration is lifted through magneto-elastic coupling, evidenced by strong anisotropic broadening of the diffraction profiles at high temperature and ultimately by a structural phase transition at 45 K. In this low-temperature regime a three-dimensional antiferromagnetic state is observed with a propagation vector k=(1/2,1/2,0).
authors.affiliation: Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, Vassilika Vouton, 71110 Heraklion, Greece.
authors.forename: Maud
authors.initials: M
authors.lastname: Giot
authors.forename: Laurent C
authors.initials: LC
authors.lastname: Chapon
authors.forename: John
authors.initials: J
authors.lastname: Androulakis
authors.forename: Mark A
authors.initials: MA
authors.lastname: Green
authors.forename: Paolo G
authors.initials: PG
authors.lastname: Radaelli
authors.forename: Alexandros
authors.initials: A
authors.lastname: Lappas