Dynamic hysteresis of magnetic aggregates with non-integer dimension

Abstract

We investigate the dynamic hysteresis of nanoscale magnetic aggregates by employing Monte Carlo simulation, based on Ising model in non-integer dimensional space. The diffusion-limited aggregation (DLA) model with adjustable sticking probability is used to generate magnetic aggregates with different fractal dimension D. It is revealed that the exponential scaling law A( H 0, ω)∼ H 0 α ·ω β , where A is the hysteresis area, H 0 and ω the amplitude and frequency of external magnetic field, applies to both the low- ω and high- ω regimes, while exponents α and β decrease with increasing D in the low- ω regime and keep invariant in the high- ω regime. A mean-field approach is developed to explain the simulated results.