SPIN DYNAMICS IN THE LINEAR-CHAIN S=1 ANTIFERROMAGNET NI(C3H10N2)(2)N-3(CLO4)

Magnetic excitations is the quasi-one-dimensional Heisenberg spin-1 an tiferromagnet Ni(C3H10N2)(2)N3ClO4) (NINAZ) have been studied by singl e-crystal inelastic neutron scattering. A Haldane gap Delta approximat e to 3.6 meV in the spin excitation spectrum was observed in the vicin ity of the antiferromagnetic wave vector at low temperature and the di spersion relation was measured. The temperature dependence of the ener gy gap Delta(T) was measured in the range 8-50 K and was found to be i nconsistent with the predictions of the quantum nonlinear sigma model. The results are discussed comparison with those found in the literatu re for similar systems.