SPIN DYNAMICS OF A ONE-DIMENSIONAL ISING-LIKE ANTIFERROMAGNET IN A TRANSVERSE MAGNETIC-FIELD

The effect of the transverse magnetic field h(x) on the spin dynamics of a one dimensional Ising-like S=1/2 antiferromagnet is discussed. Based on a picture of the propagating domain walls, we obtain dynamical spin correlation functions along the magnetic field S-xx(k, omega) and perpendicular to it S-yy(k, omega). A remarkable effect is seen in S-yy(k, omega) for pi/2 less than or equal to k less than or equal to pi, where the spectral weight moves toward the low energy side with the increase of h(x). The theory is applied to the analysis of the spin dynamics of CsCoCl3, taking into account weak interchain interactions. Zeeman ladders occur and S-yy(k, omega) for k similar to pi exhibits a novel feature under the existence of h(x).