This review summarizes recent developments in the theory of spin glasses, as well as pertinent experimental data. The most characteristic properties of spin glass systems are described, and related phenomena in other glassy systems (dielectric and orientational glasses) are mentioned. The Edwards-Anderson model of spin glasses and its treatment within the replica method and mean-field theory are outlined, and concepts such as "frustration," "broken replica symmetry," "broken ergodicity," etc., are discussed. The dynamic approach to describing the spin glass transition is emphasized. Monte Carlo simulations of spin glasses and the insight gained by them are described. Other topics discussed include site-disorder models, phenomenological theories for the frozen phase and its excitations, phase diagrams in which spin glass order and ferromagnetism or antiferromagnetism compete, the Ne\'el model of superparamagnetism and related approaches, and possible connections between spin glasses and other topics in the theory of disordered condensed-matter systems.

Spin glasses: Experimental facts, theoretical concepts, and open questions

A generalised, dilute, infinite-ranged Ising spin-glass model is introduced and studied as a function of the concentration p and temperature T. The phase diagram is investigated and paramagnetic (P), ferromagnetic (F), spin glass (SG) and mixed (M) phases, meeting at a multicritical point (p*,T*), are identified. The P/F and P/SG phase boundaries are derived, and the F/M and M/SG boundaries are calculated close to (p*,T*). The condition for having a re-entrant spin-glass transition is derived. In non-zero magnetic field a p-dependent A-T instability line is obtained. The authors apply their results to the insulator EuxSr1-xS, it is predicted to exhibit re-entrant behaviour.

https://iopscience.iop.org/article/10.1088/0022-3719/18/15/013/pdf

Phase diagrams for dilute spin glasses

Spin glasses (I)

Some experimental aspects of spin glasses: A review

Spin Glasses (II)

It is demonstrated that for a vector spin-glass in a magnetic field, replica-symmetry breaking, the theoretical indicator for magnetic irreversibility, occurs simultaneously with transverse spin-glass ordering as the temperature is reduced. It is argued that the irreversibility onset will be strong in the transverse direction, but only weak longitudinally, with a crossover to strong longitudinal irreversibility at a lower temperature.

Marc Gabay

Papers

Instabilities of an m -Vector Spin-Glass in a Field