Dielectric and magnetic anomalies and spin frustration in hexagonal RMnO3 (R = Y, Yb, and Lu) -: art. no. 104419

Single crystals of hexagonal RMnO3 (R = Y, Yb, and Lu), where Mn ions form the triangular lattice, were investigated, focusing on their dielectric/magnetic anomalies as well as geometrical spin frustration. It is found that the ratio of a Weiss temperature to T-N is similar to 10 in RMnO3, indicating the dominant role of strong geometrical frustration. The effect of geometrical frustration also appears in specific heat, which shows a presence of a substantial amount of residual magnetic contribution below T-N, indicating that a part of the spins are still fluctuating at T much less thanT(N). It is also found that the dielectric anomaly at T-N is strongly anisotropic, suggesting a unique correlation between magnetism and dielectric properties in these compounds.