Domain dynamics and fluctuations in artificial square ice at finite temperatures

Abstract

The thermally driven formation and evolution of vertex domains is studied for square artificial spin ice. A self-consistent mean-field theory is used to show how domains of ground state ordering form spontaneously, and how these evolve in the presence of disorder. The role of fluctuations is studied using Monte Carlo simulations and analytical modelling. Domain wall dynamics are shown to be driven by a biasing of random fluctuations towards processes that shrink closed domains, and fluctuations within domains are shown to generate isolated small excitations, which may stabilize as the effective temperature is lowered. Domain dynamics and fluctuations are determined by interaction strengths, which are controlled by inter-element spacing. The role of interaction strength is studied via experiments and Monte Carlo simulations. Our mean-field model is applicable to ferroelectric 'spin' ice, and we show that features similar

Coarsening phenomena

“…Optical microscopy is commonly used to study domain growth in polymer thin films [13]. Magnetic force microscopy, photoemission electron microscopy and Lorentz transmission electron microscopy are used to visualise the magnetic moment configurations in artificial magnetic materials, such as the 2d spin-ice samples [14,15] that undergo two kinds of order-disorder phase transitions across which stripe magnetic ordering develops [16][17][18][19].…”

FePd3as a material for studying thermally active artificial spin ice systems

“…There have been a number of studies focused on how disorder affects ground state formation in artificially frustrated systems [34,[38][39][40]. In our samples, there is a disordered spread in the width of the magnets due to lithography artifacts, arising from slight local variations in electron dose due to shot noise.…”

“…Monte Carlo simulations have proven to be a successful approach in understanding complex behavior in other ASI systems [25,[32][33][34][35]. We use a kinetic Monte Carlo technique [36] similar to other models of thermal ASI [19,20].…”

New physics in frustrated magnets: Spin ices, monopoles, etc. (Review Article)

“…For example, artificial spin ice systems were proposed to be constructed as arrays of optical traps [267,268]. A large number of experiments and theories since 2006 have considered artificial spin ice systems, including planes of ferromagnetic islands with square, honeycomb and Kagome lattices [269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,295]. In particular, it has been shown using magneto-optical Kerr effect that disorder in the roughness (in shape) of magnetic islands plays essential role in the collective behavior of artificial spin ices [296,297].…”