Spin-cluster excitations in RbFeCl3·2H2O

Abstract
Spin-cluster excitations (SCE) from the ground state are observed in the pseudo-one-dimensional canted Ising antiferromagnet RbFeCl3·2H2O. Since the moments are canted with respect to each other, SCE were observed which show characteristics of a ferromagnetic chain and an antiferromagnetic chain when the external field is along the c or a axis, respectively. The results cannot be interpreted with the simple Ising model as in the case of spin-cluster resonance (SCR) reported earlier. For the small spin clusters observed in the present experiment, it is necessary to include effects from the higher single-ion states. Together with SCR the data provide rather detailed information on the magnetic ground state and the interactions.