Spin-glass and related orderings in quenched random-spin systems

A general model in which the nearest-neighbor exchange interactions J(x ,x ′) are of the form J(x ,x ′)=J1+J2e(x )e(x ′)+J3[e(x )+e(x ′)]+J4μ(x ,x ′) is considered. Here e(x ) is a random site variable and μ(x ,x ′) 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.