Out-of-equilibrium dynamics and extended textures of topological defects in spin ice
Physical Review B
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Udagawa, M., Jaubert, L., Castelnovo, C., & Moessner, R. (2016). Out-of-equilibrium dynamics and extended textures of topological defects in spin ice. Physical Review B, 94 (10)https://doi.org/10.1103/PhysRevB.94.104416
© 2016 American Physical Society.Memory effects have been observed across a wide range of geometrically frustrated magnetic materials, possibly including Pr2Ir2O7 where a spontaneous Hall effect has been observed. Frustrated magnets are also famous for the emergence of topological defects. Here we explore how the interaction between these defects can be responsible for a rich diversity of out-of-equilibrium dynamics, dominated by topological bottlenecks and multiscale energy barriers. Our model is an extension of the spinice model on the pyrochlore lattice, where farther-neighbor spin interactions give rise to a nearest-neighbor coupling between topological defects. This coupling can be chosen to be "unnatural" or not, i.e., attractive or repulsive between defects carrying the same topological charge. After applying a field quench, our model supports, for example, long-lived magnetization plateaux, and allows for the metastability of a "fragmented" spin liquid, an unconventional phase of matter where long-range order co-exists with a spin liquid. Perhaps most strikingly, the attraction between same-sign charges produces clusters of these defects in equilibrium, whose stability is due to a combination of energy and topological barriers. These clusters may take the form of a "jellyfish" spin texture, centered on a hexagonal ring with branches of arbitrary length. The ring carries a clockwise or counterclockwise circular flow of magnetization. This emergent toroidal degrees of freedom provide a possibility for time-reversal symmetry breaking with potential relevance to the spontaneous Hall effect observed in Pr2Ir2O7.
External DOI: https://doi.org/10.1103/PhysRevB.94.104416
This record's URL: https://www.repository.cam.ac.uk/handle/1810/283455