HYSTERESIS PHENOMENA AND BARKHAUSEN-LIKE INSTABILITIES IN THE SHERRINGTON-KIRKPATRICK SPIN-GLASS MODEL

We investigate by computer simulations the hysteresis and instability phenomena taking place in the Sherrington-Kirkpatrick (SK) spin-glass model at zero temperature in the presence of field H varying in time at a given rate ∥Ḣ∥. At low ∥Ḣ∥, the system evolves by well-separated Barkhausen-like spin-flip clusters, which generate through a branching mechanism a sequence of metastable spin configurations associated with different values of H. On this basis, a new method to search for the lowest-energy states by applying a proper field history is proposed. The spin behavior versus ∥Ḣ∥ is studied by evaluating the power spectrum of the magnetization rate associated with spin flipping. Close similarities with the properties of the Barkhausen effect in ferromagnetic materials are found. This result suggests that the SK model can to some extent describe the intricate, long-range magnetostatic interactions governing Barkhausen effect phenomenology.