Prof. Philippe Sindzingre (Universite Pierre & Marie Curie)
"Phase diagram of J1-J2-J3 model of spin-1/2 on the square lattice"

@Results obtained, for the J1-J2-J3 model with ferromagnetic first neighbor exchange coupling J1, by means of exact diagonalization and spin wave calculation are presented. These calculations shows that quantum fluctuations strongly modify the extension of the phases present classically, affect the value of the wave vector of the spiral phases and induces new phases not present classically. The model is shown to exhibit under an applied magnetic field, a magnetization a plateau at 1/3 of the saturated magnetization in a certain region of parameter space. Those results are discussed in view of experimental data.