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

Article

关键词: MONTE-CARLO-SIMULATION;    MAGNETIC MONOPOLE;    PYROCHLORE MAGNETS;    COULOMB PHASE;    FRUSTRATION;    SYSTEMS;    ANTIFERROMAGNET;    FRAGMENTATION;    DY2TI2O7;    HO2TI2O7;   

DOI  :  10.1103/PhysRevB.94.104416

来源: SCIE

【 摘 要 】

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.

【 授权许可】

Free