2025/06/02 by D. A. Garanin, Garanin, D. A. · 1 citation
Materials Science · #FOS: Physical sciences #Magnetic Properties and Applications #Statistical Mechanics (cond-mat.stat-mech)
paper · doi:10.48550/arxiv.2506.02292
openalex publication_date 2025/06/02 · openalex created_date 2025/10/14 · openalex updated_date 2026/07/28
Energy minimization at T=0 and Monte Carlo simulations at T>0 have been performed for 2D and 3D random-field and random-anisotropy systems of up to 100 million classical spins. The main finding is that 3D random-anisotropy systems magnetically order on lowering temperature, contrary to the theoretical predictions based on the Imry-Ma argument. If random-anisotropy is stronger than the exchange, which can be the case in sintered materials, the system still orders but the magnetization is strongly reduced and there is a large spin-glass component in the spin state, the heat capacity having a cusp instead of a divergence. 3D random-field systems do not magnetically order on lowering temperature but rather freeze into the correlated spin-glass state. Here, although magnetized local energy minima have lower energies than non-magnetized ones, magnetic ordering is prevented by singularities pinned by the random field.