Spin-Glass and Related Orderings in Quenched Random-Spin Systems

A general model in which the nearest-neighbor exchange interactions J(x⃗ ,x⃗ ′) are of the form J(x⃗ ,x⃗ ′)=J1+J2ε(x⃗ )ε(x⃗ ′)+J3[ε(x⃗ )+ε(x⃗ ′)]+J4μ(x⃗ ,x⃗ ′) is considered. Here ε(x⃗ ) is a random site variable and μ(x⃗ ,x⃗ ′) is a random bond variable. It is argued that J4 tends to produce the Edwards-Anderson-type spin glass, whereas J2 produces a different type of phase which is like an alloy of up and down spins. That these two phases are distinct follows from the existence of a phase boundary in the J2−J4 plane when J1=J3=0. A consistent, but qualitative, discussion of this model via the renormalization group is also given.