Possibility of a chiral phase transition in 2D solid 3He

We study a spin system with both two-and four-spin exchange interactions on the triangular lattice, which is a possible model for the nuclear magnetism of solid He-3 layers. We find that a novel phase with scalar chiral order appears if the four-spin interaction is dominant. Ground-state properties are studied using the spin-wave approximation. A phase transition concerning the scalar chirality occurs at a finite temperature, since the chirality is an Ising-type variable. Critical phenomena of this transition are studied by Monte Carlo simulations in the classical limit. (C) 1998 Elsevier Science B.V. All rights reserved.