Spin correlation in the diluted triangular-lattice antiferromagnetLuFeMgO4

Abstract

Spin correlation in the diluted triangular-lattice antiferromagnet LuFeMgO${}_{4}$ has been investigated. LuFeMgO${}_{4}$ is one of the simplest insulating antiferromagnets where spin-glass-like random freezing is caused by random dilution of the frustrating antiferromagnetic interactions. Several magnetic properties obtained by Monte Carlo simulation are compared with experimental results including neutron scattering on a single crystal. Possible ionic distribution of Fe${}^{3+}$ and Mg${}^{2+}$ on the triangular lattice is also examined. The simulation reproduces the characteristic short-range spin correlation remarkably well and provides a qualitative description on the ``observed'' freezing in this two-dimensional model system. The short-range spin correlation itself does not change significantly at the freezing temperature but forms a long-range network of quasistatic spins. At lower temperature, a higher order structure of the short-range correlation is expected as a consequence of the residual degree of freedom on the cluster orientation.