title: Anharmonic effect on lattice distortion, orbital ordering and magnetic properties in Cs(2)AgF(4).
abstract: We develop the cluster self-consistent field method incorporating both electronic and lattice degrees of freedom to study the origin of ferromagnetism in Cs(2)AgF(4). After self-consistently determining the harmonic and anharmonic Jahn-Teller distortions, we show that the anharmonic distortion stabilizes the staggered x(2)-z(2)/y(2)-z(2) orbital and ferromagnetic ground state, rather than the antiferromagnetic one. The amplitudes of lattice distortions, Q(2) and Q(3), the magnetic coupling strengths, J(x,y), and the magnetic moment are in good agreement with the experimental observations.
authors.affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, PO Box 1129, Hefei 230031, People's Republic of China. Graduate School of the Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
authors.forename: Da-Yong
authors.initials: DY
authors.lastname: Liu
authors.forename: Feng
authors.initials: F
authors.lastname: Lu
authors.forename: Liang-Jian
authors.initials: LJ
authors.lastname: Zou