Finite-temperature properties of the extended Heisenberg model on a triangular lattice

We present numerical results for the J(1)-J(2) Heisenberg model on a triangular lattice at finite temperatures T > 0. In contrast to unfrustrated lattices we reach much lower T similar to 0.15J(1). In static quantities the novel feature is a quite sharp low-T maximum in the specific heat. Dynamical spin structure factor S(q, omega) allows for the extraction of the effective spin-wave energies omega(q)(T) and their damping gamma(q)(T). While for J(2) = 0 our results are consistent with T = 0 spin ordering, J(2)/J(1) similar to 0.1 induces additional frustration with a signature of spin-liquid ground state. In the latter case, the results for the spin-lattice relaxation rate indicate the low- T accessible regime on 1/T-1 proportional to T-alpha with alpha >= 1, as observed in recent spin-liquid materials on a triangular lattice.