Finite-temperature dynamical magnetic susceptibility of quasi-one-dimensional frustrated spin-1/2 Heisenberg antiferromagnets - art. no. 094425

We study the dynamical response of frustrated, quasi-one-dimensional spin-1 /2 Heisenberg antiferromagnets at finite temperatures. We allow for the pre sence of a Dzyaloshinskii-Moriya interaction. We concentrate on a model of weakly coupled planes of anisotropic triangular lattices. Combining exact r esults for the dynamical response of one-dimensional Heisenberg chains with a random-phase approximation in the frustrated interchain couplings, we ca lculate the dynamical susceptibility in the disordered phase. We investigat e the instability of the disordered phase to the formation of collective mo des. We find a very weak instability to the formation of incommensurate mag netic order and determine the ordering temperature and wave vector. We also determine the effects of uniform magnetic fields on the ordering transitio n.