Broken vertex symmetry and finite zero-point entropy in the artificial square ice ground state

Gliga, Sebastian; Kákay, Attila; Heyderman, Laura J.; Hertel, Riccardo; Heinonen, Olle

doi:10.1103/physrevb.92.060413

Cited by 45 publications

(68 citation statements)

References 24 publications

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“…By dividing each magnetic island into three equidistant spins, we now have access to 12 bands. In the ground state, three configurations are stable: homogeneous or onion [25], C, and S states. The corresponding band diagrams are shown in Fig.…”

Section: Band Structure In Square Icesmentioning

confidence: 99%

“…Furthermore, the particular magnetic configuration quantitatively modifies the band diagram, indicating that edge bending can be compared to impurity states in semiconductor materials. Because a transition between C and S states can be induced by, e.g., temperature [25], this can be used as another avenue to program the magnonic response of the square ice. In the remanent state, the unit cell is composed of two magnetic islands, Fig.…”

Section: Band Structure In Square Icesmentioning

confidence: 99%

“…More recently, a detailed numerical study has shown that edge modes arising from the internal degrees of freedom of the magnetization equally have observable consequences in the resonant spectrum in sufficiently thick nanoislands [25]. In fact, edge modes efficiently couple neighboring nanoislands, influencing the collective oscillations [20].…”

Section: Introductionmentioning

confidence: 99%

“…The vortex state is the ground state of the system, achieved by thermal relaxation [32], and the remanent state can be obtained by saturating the system in an external field along the (x,ŷ) direction, and then slowly removing the external field, letting the system relax. In each configuration, the magnetization can bend close to the nanoisland edges [25], providing a local "impurity." In square ices, two stable edge configurations satisfy the minimization of dipolar fields in the ground state, resulting in C and S states [33][34][35], Figs.…”

Section: Introductionmentioning

confidence: 99%

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Reconfigurable wave band structure of an artificial square ice

et al. 2016

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Artificial square ices are structures composed of magnetic nanoelements arranged on the sites of a twodimensional square lattice, such that there are four interacting magnetic elements at each vertex, leading to geometrical frustration. Using a semianalytical approach, we show that square ices exhibit a rich spin-wave band structure that is tunable both by external magnetic fields and the magnetization configuration of individual elements. Internal degrees of freedom can give rise to equilibrium states with bent magnetization at the element edges leading to characteristic excitations; in the presence of magnetostatic interactions these form separate bands analogous to impurity bands in semiconductors. Full-scale micromagnetic simulations corroborate our semianalytical approach. Our results show that artificial square ices can be viewed as reconfigurable and tunable magnonic crystals that can be used as metamaterials for spin-wave-based applications at the nanoscale.

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Section: Band Structure In Square Icesmentioning

confidence: 99%

Section: Band Structure In Square Icesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reconfigurable wave band structure of an artificial square ice

et al. 2016

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“…28 Micromagnetic calculations using MuMax 329 revealed non-collinearities of the moment within the islands. A reduced effective moment of approximately m 0,eff = 0.65 × m 0 = 4.2 × 10 6 µ B at T = 0 K, is used to compensate for the dynamic non-collinear internal magnetic structure of the elements (see Andersson et al 16 , Bessarab et al 30 , Bessarab et al 31 and Gliga et al 32 ).…”

Section: Methodsmentioning

confidence: 99%

Collective magnetic dynamics in artificial spin ice probed by ac susceptibility

et al. 2020

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We report on the study of the thermal dynamics of square artificial spin ice, probed by means of temperature and frequency dependent AC susceptibility. Pronounced influence of the inter-island coupling strength was found on the frequency response of the samples. Through the subsequent analysis of the frequency-and coupling-dependent freezing temperatures, we discuss the phenomenological parameters obtained in the framework of Vogel-Fulcher-Tammann law in terms of the samples microscopic features. The high sensitivity and robust signal to noise ratio of AC susceptibility validates the latter as a promising and simple experimental technique for resolving the dynamics and temperature driven dynamics crossovers for the case of artificial spin ice.

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Field‐Driven Reversal Models in Artificial Spin Ice

Paterson

Macauley

Macêdo

2021

Advcd Theory and Sims

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A set of topological arrangements of individual ferromagnetic islands in ideal and disordered artificial spin ice (ASI) arrays is investigated in order to evaluate how aspects of their field-driven reversal are affected by the model used. The set contains the pinwheel and square ice tilings, and thus a range of magnetic ordering and reversal properties are tested. It is found that a simple point dipole model performs relatively well for square ice, but it does not replicate the properties observed in recent experiments with pinwheel ice. Parameterization of the reversal barrier in a Stoner-Wohlfarth model improves upon this, but fails to capture aspects of the physics of ferromagnetic coupling observed in pinwheel structures which have been attributed to the non-Ising nature of the islands. In particular, spin canting is found to be important in pinwheel arrays, but not in square ones, due to their different symmetries. The authors' findings will improve the modeling of ASI structures for fundamental research and in applications which are reliant upon the ability to obtain and switch through known states using an externally applied field.

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Broken vertex symmetry and finite zero-point entropy in the artificial square ice ground state

Cited by 45 publications

References 24 publications

Reconfigurable wave band structure of an artificial square ice

Reconfigurable wave band structure of an artificial square ice

Collective magnetic dynamics in artificial spin ice probed by ac susceptibility

Field‐Driven Reversal Models in Artificial Spin Ice

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