Nonequilibrium critical behavior of magnetic thin films grown in a temperature gradient

Abstract

We investigate the irreversible growth of (2 + 1)−dimensional magnetic thin films under the influence of a transverse temperature gradient, which is maintained by thermal baths across a direction perpendicular to the direction of growth. Therefore, different longitudinal layers grow at different temperatures between T 1 and T 2 , where T 1 < T hom c < T 2 and T hom c = 0.69(1) is the critical temperature of films grown in homogeneous thermal baths. We find a far-from-equilibrium continuous order-disorder phase transition driven by the thermal bath gradient. We characterize this gradient-induced critical behavior by means of standard finite-size scaling procedures, which lead to the critical temperature T c = 0.84(2) and a new universality class consistent with the set of critical exponents ν = 3/2, γ = 5/2, and β = 1/4. In order to gain further insight into the effects of the temperature gradient, we also develop a bond model that captures the magnetic film's growth dynamics. Our findings show that the interplay of geometry and thermal bath asymmetries leads to growth bond flux asymmetries and the onset of transverse ordering effects that explain qualitatively the shift observed in the critical temperature. The relevance of these mechanisms is further confirmed by a finite-size scaling analysis of the interface width, which shows that the growing sites of the system define a self-affine interface.

Thin film deposition with time-varying temperature

“…The control of these temperature changes are realistic for thin film growth. For comparision, in film deposition with the substrate subject to a temperature gradient, much larger temperature differences are stablished [26,27]. An example is F eP t film growth with the temperature varying from 250 o C to 600 o C along a substrate distance smaller than 1cm [26]).…”

Magnetic hysteresis, compensation behaviors, and phase diagrams of bilayer honeycomb lattices

“…The Ising model is a well-known pioneering theoretical model that is widely used in magnetic systems and which plays an important role in understanding in-depth the phase transitions and critical phenomena. Recently, thin films have been widely studied by means of Monte Carlo (MC) simulations, [36][37][38][39][40][41] mean-field approach (MFA), [42][43][44] and the effective-field theory (EFT) [45][46][47][48][49][50][51] along with well-known theoretical methods in equilibrium statistical physics in the liter-ature of Ising systems. Despite these studies, as far as we know, the hysteresis and compensation behaviors of BHL Ising system have not been investigated.…”

Stochastic resonance and dynamic first-order pseudo-phase-transitions in the irreversible growth of thin films under spatially periodic magnetic fields

“…The key to understanding the crossover from the SSR to the ASR regime is to notice that, analogously to other kinds of surface growth phenomena, thin films grow with a rough interface, whose saturated width in the stationary regime scales with the lattice size as w ∝ L α [34,44]. For magnetic Eden model thin films, w = a × L with a < 1 [45]. The snapshots from Fig.…”