SPIN CORRELATION IN THE DILUTED TRIANGULAR-LATTICE ANTIFERROMAGNET LUFEMGO4

Spin correlation in the diluted triangular-lattice antiferromagnet LuF eMgO4 has been investigated. LuFeMgO4 is one of the simplest insulatin g antiferromagnets where spin-glass-like random freezing is caused by random dilution of the frustrating antiferromagnetic interactions. Sev eral magnetic properties obtained by Monte Carlo simulation are compar ed with experimental results including neutron scattering on a single crystal. Possible ionic distribution of Fe3+ and Mg2+ on the triangula r lattice is also examined. The simulation reproduces the characterist ic short-range spin correlation remarkably well and provides a qualita tive 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 netwo rk of quasistatic spins. At lower temperature, a higher order structur e of the short-range correlation is expected as a consequence of the r esidual degree of freedom on the cluster orientation.