INERGODICITY AND DYNAMICAL PHASE-TRANSITIONS IN THE SOFT SPHERICAL SPIN-GLASS MODEL

The appearance of infinite relaxation times indicating the breaking of ergodicity in the spin-glass phase is demonstrated in the analytical study of finite-field dynamics of the soft spherical spin-glass model. The finite-field inergodic effects such as the difference between fie ld-cooled and zero-field-cooled (ZFC) magnetizations and history depen dence of a hysteresis loop were described for the case of the infinite -range random exchange. The existence of the dynamical phase transitio ns resulting from the jumps over finite microscopic barriers and trapp ing in the ZFC subspace were established in this case. The hysteresis loop form was analyzed for various temperatures, frequencies, and ampl itudes of the external ac field.