Anharmonic effect on lattice distortion, orbital ordering and magnetic properties in Cs2AgF4

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 strengthes, J${}_{x,y}$, and the magnetic moment, are in good agreement with the experimental observation.

13 pages, 5 figures

References in corpus (3)

• Magnetism in the high-Tc analogue Cs2AgF4 studied with muon-spin relaxation
• Origin of ferromagnetism in Cs${}_2$AgF${}_4$: importance of Ag - F covalency
• Orbital ordering in the ferromagnetic insulator Cs${}_2$AgF${}_4$ from first principles