Thermodynamic phase transitions in a frustrated magnetic metamaterial

Anghinolfi, Luca; Luetkens, H.; Perron, Justin K.; Flokstra, M. G.; Sendetskyi, Oles; Suter, A.; Prokscha, T.; Derlet, P. M.; Lee, Stephen; Heyderman, Laura J.

doi:10.1038/ncomms9278

Cited by 127 publications

(123 citation statements)

References 29 publications

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“…These values correspond to the plateaux observed in Fig. 12 With the peculiar exceptions of models where double charges were explicitly forbidden 37,38 , and 2D artificial kagome ice systems [40][41][42][43][44] , the FCSL has been noticeably elusive at equilibrium in 3D spin-ice models 46 , despite its deceptive simplicity.…”

Section: Numerical Setup For Field Quenchessupporting

confidence: 74%

“…A configuration in the Coulomb phase of spin ice is entirely covered with two-in two-out tetrahedra, while a FCSL configuration is alternatively covered by 3-in 1-out and 3-out 1-in tetrahedra: the four nearest-neighbours of a 3-in 1-out tetrahedron are 3-out 1-in tetrahedra, and vice-versa. The FCSL has been predicted theoretically 40,41 and observed experimentally [42][43][44] in nano-lithographic artificial kagome ice whose geometry prevents the existence of a charge-free Coulomb phase 45 . But in three dimensions, it has so far only been partially stabilized at equilibrium in the spin-ice model with dipolar interactions 46 , or requires four-body interactions 39 or the suppression of double charges 37,38 .…”

Section: Model and Summary Of Main Resultsmentioning

confidence: 96%

“…We hope our work will further motivate the exploration of nonequilibrium phenomena in geometrically frustrated magnets, ranging from topological ergodicity breaking 74 to glassiness without disorder 18,23 , and with connections to kagome systems 75,76 including their realization in artificial spin ice [40][41][42][43][44] and the 16-vertex model 54,55 .…”

Section: Discussionmentioning

confidence: 94%

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Out-of-equilibrium dynamics and extended textures of topological defects in spin ice

et al. 2016

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We study the interplay of topological bottlenecks and energetic barriers to equilibration in a Coulomb spin liquid where a short-range energetic coupling between defects charged under an emergent gauge field supplements their entropic long-range Coulomb interaction. This work is motivated by the prevalence of memory effects observed across a wide range of geometrically frustrated magnetic materials, possibly including the spontaneous Hall effect observed in Pr2Ir2O7. Our model is canonical spin-ice model on the pyrochlore lattice, where farther-neighbour spin couplings give rise to a nearest-neighbor interaction between topological defects which can easily be chosen to be "unnatural" or not, i.e. attractive or repulsive between defects of equal gauge charge. Among the novel features of this model are the following. After applying a field quench, a rich dynamical approach to equilibrium emerges, dominated by multi-scale energy barriers responsible for long-lived magnetization plateaux. These even allow for the metastability of a "fragmented" spin liquid, an elusive regime where partial order co-exists with a spin liquid. Perhaps most strikingly, the attraction produces clusters of defects whose stability is due to a combination of energetic barriers for their break-up and proximity of opposite charges along with an entropic barrier generated by the topological requirement of annihilating a defect only together with an oppositely charged counterpart. These clusters may take the form of a "jellyfish" spin texture, comprising an arrangement of same-sign gauge-charges, centered on a hexagonal ring with branches of arbitrary length. The ring carries a clockwise or counterclockwise circular flow of magnetisation. This emergent toroidal degrees of freedom provides a possibility for time reversal symmetry breaking with possible relevance to the spontaneous Hall effect observed in Pr2Ir2O7.

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Section: Numerical Setup For Field Quenchessupporting

confidence: 74%

Section: Model and Summary Of Main Resultsmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 94%

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Out-of-equilibrium dynamics and extended textures of topological defects in spin ice

et al. 2016

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“…The centers of neighboring islands are separated by a distance of 170 nm. This combination leads to a weakly coupled system that is thermally active above 30 K. 11 Starting from a system containing about 3000 sites, disorder is introduced into the system by randomly selecting sites and setting the magnetic moment of those locations to zero.…”

Section: Simulationmentioning

confidence: 99%

“…10 The combination of experimental and computational work on artificial spin ice has led to a better understanding of the phases, dynamics, and interactions that take place in physical systems. [11][12][13] Square lattices of artificial spin ice have been created and shown to preserve the 2-in/2-out, low temperature configuration, at each vertex. 14 By increasing the temperature, or reducing the magnetic coupling by increasing the spacing between islands, magnetic charge excitations (monopoles) can be created which then propagate through the lattice; a subject of intense investigation.…”

Section: Introductionmentioning

confidence: 99%

Disordered kagomé spin ice

Greenberg

Kunz

2018

AIP Advances

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Artificial spin ice is made from a large array of patterned magnetic nanoislands designed to mimic naturally occurring spin ice materials. The geometrical arrangement of the kagomé lattice guarantees a frustrated arrangement of the islands’ magnetic moments at each vertex where the three magnetic nanoislands meet. This frustration leads to a highly degenerate ground state which gives rise to a finite (residual) entropy at zero temperature. In this work we use the Monte Carlo simulation to explore the effects of disorder in kagomé spin ice. Disorder is introduced to the system by randomly removing a known percentage of magnetic islands from the lattice. The behavior of the spin ice changes as the disorder increases; evident by changes to the shape and locations of the peaks in heat capacity and the residual entropy. The results are consistent with observations made in diluted physical spin ice materials.

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Spin Solid versus Magnetic Charge Ordered State in Artificial Honeycomb Lattice of Connected Elements

et al. 2018

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The nature of magnetic correlation at low temperature in two‐dimensional artificial magnetic honeycomb lattice is a strongly debated issue. While theoretical researches suggest that the system will develop a novel zero entropy spin solid state as T → 0 K, a confirmation to this effect in artificial honeycomb lattice of connected elements is lacking. This study reports on the investigation of magnetic correlation in newly designed artificial permalloy honeycomb lattice of ultrasmall elements, with a typical length of ≈12 nm, using neutron scattering measurements and temperature‐dependent micromagnetic simulations. Numerical modeling of the polarized neutron reflectometry data elucidates the temperature‐dependent evolution of spin correlation in this system. As temperature reduces to ≈7 K, the system tends to develop novel spin solid state, manifested by the alternating distribution of magnetic vortex loops of opposite chiralities. Experimental results are complemented by temperature‐dependent micromagnetic simulations that confirm the dominance of spin solid state over local magnetic charge ordered state in the artificial honeycomb lattice with connected elements. These results enable a direct investigation of novel spin solid correlation in the connected honeycomb geometry of 2D artificial structure.

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Thermodynamic phase transitions in a frustrated magnetic metamaterial

Cited by 127 publications

References 29 publications

Out-of-equilibrium dynamics and extended textures of topological defects in spin ice

Out-of-equilibrium dynamics and extended textures of topological defects in spin ice

Disordered kagomé spin ice

Spin Solid versus Magnetic Charge Ordered State in Artificial Honeycomb Lattice of Connected Elements

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