Intermediate phase and pseudo phase transition in an artificial spin ice model

Abstract

In this paper we conduct Monte Carlo simulations to investigate the thermodynamic properties of a geometry of artificial spin ice recently proposed in the literature that had been termed "rewritable" spin ice, for its experimental realization allows total control over the microstates of the system. Our results show that in the thermodynamic limit a single phase transition between a fully magnetized state and a paramagnetic state exists, whereas for finite systems an intermediate phase also emerges, engendering a low temperature pseudo phase transition. This intermediate phase is characterized by large magnetic domains separated by domain walls composed of monopole-like excitations, resulting in low net magnetization values. We also show that two types of low energy excitations that behave as magnetic monopoles emerge in the system, both of which are geometrically constrained to move along a predefined path.