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A magnetic electrolyte - monopole quasi-particles in spin ice
Models for the frustrated magnetic material "spin ice" show the
remarkable property of fractionalization of magnetic moments into
effective free magnetic charge : magnetic monopoles [1]. The
development of experimental signatures of the presence of monopoles in spin ice materials, Holmium and Dysprosium Titanate is hence one of the most engaging and exciting challenges of condensed matter physics.
In this talk I will review the static and dynamic properties of this
magnetic electrolyte - a magnetolyte, in the context of a generalized description of a lattice Coulomb gas [2]. I will discuss a theory of diffusive monopole dynamics, motivated by magnetic relaxation measurements on both materials [3]. I will show that the relaxation rate of the underlying network of constraints, which are classical analogues of Dirac strings, is in quantitative agreement with that for magnetic relaxation in Dy2Ti2O7 [4]. This agreement provides an explanation for the non- standard nature of spin freezing in spin ice compounds and gives strong evidence for the presence of monopoles.
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