Effects of geometrical frustration on the spin-glass transition

Randomness and frustration are important for the spin-glass transitions. Ising antiferromagnet on a stacked triangular lattice is a highly frustrated system. Phase diagram is obtained within a cluster approximation for the system with randomness in the interaction between Ising spins. To see the frustration effects, the phase diagram of the antiferromagnet is compared with the corresponding one of the ferromagnet. Spin-glass phase of the antiferromagnet appears much more easily by the randomness than that of the ferromagnet.