SPIN-CLUSTER RESONANCE IN THE PSEUDO-ONE-DIMENSIONAL CANTED ISING ANTI-FERROMAGNET RBFECL3.2H2O

Spin-cluster resonance (SCR) is observed in the pseudo-one-dimensional canted Ising antiferromagnet RbFeCl3•2H2O. Transitions between clusters up to 9 spins (|m>|m+9>) could be detected. Since the moments in the chain are canted with respect to each other, SCR were observed which show characteristics of a ferromagnetic chain and an antiferromagnetic chain for the external magnetic field parallel to the c and a axis, respectively. The experimental data for H→c→ could excellently be described by a pure Ising model, with Jbk=0.76 K, Jck=-0.21 K, Jbck=-0.13 K, μ→•H→|H→|=1.50 μB, and a correction for a demagnetizing field. In order to describe the SCR for H→a→ the influence of the crystal-field splitting of the pseudo-ground-doublet of the Fe2+ ion had to be taken into account. © 1979 The American Physical Society.