A microscopic theory beyond the Ising model of spin ice

Orateur : Bruno TOMASELLO (Kent University & ISIS (STFC spallation facility at the Rutherford Appleton Laboratory))

The study of the crystal-field interactions is often the starting point for the characterisation of new phases of matter in condensed matter systems. In spin-ice materials the interaction between rare earth (RE) ions with large dipolar moments and their electric crystalline environment sets the physical constraints driving the occurrence of classical frustration in the ground state and so the emergence of magnetic monopoles as low energy excitations. In this talk I will present a quantum mechanical description of the interaction between a spin-ice RE-ion and its surrounding crystal-field environment, emphasising on the characteristic degrees of freedom allowed by the local symmetries. This is presented as part of a broader study focused on the interplay between quantum and classical mechanics of the magnetic ions in pyrochlore oxides, whose aim, in the context of spin-ice materials, is to account for the spin-flip dynamics underpinning the diffusion of the magnetic monopoles.

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