Degenerate and chiral states in the extended Heisenberg model in the kagome lattice

Abstract: We present a study of the low temperature phases of the antiferromagnetic extended classical Heisenberg model in the kagome lattice, up to third nearest neighbors. First, we focus on the degenerate lines in the boundaries of the well-known staggered chiral phases. These boundaries have either semi-extensive or extensive degeneracy, and we discuss the partial selection of states by thermal fluctuations. Then, we study the model under an external magnetic field on these lines and in the staggered chiral phases. We pay particular attention to the highly frustrated point, where the three exchange couplings are equal. We show that this point can me mapped to a model with spin liquid behavior and non-zero chirality. Finally, we explore the effect of Dzyaloshinskii-Moriya (DM) interactions in two ways: an homogeneous and a staggered DM interaction. In both cases, there is a rich low temperature phase diagram, with different spontaneously broken symmetries and non trivial chiral phases.