Static and dynamic spin correlations in the random one-dimensional antiferromagnetic CsCoxMg1-xCl3

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Abstract
Static and dynamic spin correlations in the random quasi-one-dimensional Ising-like antiferromagnet CsCo0.83Mg0.17Cl3 have been investigated by neutron scattering. The three-dimensional magnetic ordering temperature is strongly suppressed by the presence of impurities. The one-dimensional correlation length tends to a geometric limit at low temperatures in analogy with percolation in higher-dimensional magnetic systems. The quasi-elastic scattering is well described by exact calculations of Szz(Q) for a dilute chain. In addition to the usual spin wave band of the host crystal, the spectrum contains localised modes that arise from the oscillations of spins at the ends of magnetic chains. Their frequency is approximately half that of the host band. Calculations have been made of the weighted contributions to Sxx (Q, omega ) from each randomly occurring length of chain and good agreement with experiment is obtained.