FERROMAGNETIC SHORT-RANGE CORRELATIONS IN A 2-DIMENSIONAL TRIANGULAR LATTICE ANTIFERROMAGNET WITH S = 1/2 LINIO2

We have demonstrated that a two-dimensional triangular lattice antiferromagnet with spin=1/2 LiNiO2 reveals ferromagnetic short-range spin correlations in forward scattering below TN1 ~240 K, unlike other two-dimensional trianglar lattice antiferromagnets. The intensity of diffuse scattering in the forward direction appears below TN1, and monotonically increases as the temperature is lowered, then shows a sharp divergence at TN2 ~35 K. The present results suggest that a frozen spin pattern with the ferromagnetic short-range correlation similar to the spin glass phase is realized at the low-temperature phase below TN2. In contrast, no appreciable intensity was detected around the (1/3, 1/3, n) positions, being consistent with early studies. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.