NEUTRON-SCATTERING STUDY OF A ONE-DIMENSIONAL ISING-LIKE ANTI-FERROMAGNET CSCOCL3 .2. SPIN DYNAMICS

Following the previous study on the 1D Ising antiferrormagnet CsCoCl3. the dynamical spin correlation has been studied in a wide range of temperature. The observed spin wave spectrum is Ising-like with J/k =75 K but the temperature dependence is unusual. No softening of the spin wave frequencies occurs, but the peak becomes broad and the intensity falls off with increasing temperature from the high q side. Well behaved spin wave peaks whose wave lengths are much longer than the correlation length κ-1 can be observed. Discussions are given of the criteria for the existing of spin waves. The longitudinal correlation cannot be described by the simple rigorous solution of diffusive type with reasonable parameters especially at T<|J|/k. Villain's theory of propagative relaxation is promising indicating importance of off-diagonal terms contained in the Hamiltonian. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.