Abstract
Applied magnetic fields are an important tuning parameter for artificial spin ice (ASI) systems, as they can drive phase transitions between different magnetic ground states or tune through regimes with high populations of emergent magnetic excitations (e.g., monopole-like quasiparticles). Here, using simulations supported by experiments, we investigate the thermodynamic properties and magnetic phases of square and quadrupolar ASI as a function of applied in-plane magnetic fields. Monte Carlo simulations are used to generate field-dependent maps of the magnetization, the magnetic specific heat, the thermodynamic magnetization fluctuations, and the magnetic order parameters, all under equilibrium conditions. These maps reveal the diversity of magnetic orderings and the phase transitions that occur in different regions of the phase diagrams of these ASIs, and are experimentally supported by magnetooptical measurements of the equilibrium "magnetization noise"in thermally active ASIs.
| Original language | English (US) |
|---|---|
| Article number | 094406 |
| Journal | Physical Review B |
| Volume | 105 |
| Issue number | 9 |
| DOIs | |
| State | Published - Mar 1 2022 |
Bibliographical note
Funding Information:S.A.C., M.G., and C.N. gratefully acknowledge support from the Los Alamos LDRD program. The NHMFL is supported by the National Science Foundation (NSF) DMR-1644779, the State of Florida, and the US Department of Energy (DOE). Permalloy growth (J.D.W. and C.L.) was supported by NSF DMR-1807124 and DMR-2103711. Sample design and patterning (X.Z. and P.S.) was funded by the US DOE, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under Grant No. DE-SC0020162. Work at the University of Warsaw (M.G.) was supported by the Norwegian Financial Mechanism 2014-2021 under Grant No. 2020/37/K/ST3/03656 and from the Polish National Agency for Academic Exchange within Polish Returns program under Grant No. PPN/PPO/2020/1/00030. M.G. performed the noise measurements and the Monte Carlo simulations.
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