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MA: Fachverband Magnetismus

MA 18: Topological Defects in Magnetic Materials: from Devices to Cosmos
(PhD-Student Symposium jointly with jDPG)

MA 18.9: Topical Talk

Dienstag, 12. März 2013, 13:15–13:45, H16

Magnetricity and Magnetic Monopoles in Spin ice — •Steve Bramwell — University College London

The analogy between spin configurations in spin ice materials like Ho2Ti2O7 and proton configurations in water ice, H2O, has been appreciated for many years (see Ref. [1] for a review). However it is only in the last few years that this equivalence has been extended into the realm of electrodynamics [2,3]. In this talk I shall describe our recent experimental work that identifies emergent magnetic charges ("monopoles"), transient magnetic currents ("magnetricity") and the universal properties expected of an ideal magnetic Coulomb gas (magnetic electrolyte - "magnetolyte"). These universal properties include the Onsager-Wien effect, "corresponding states" behaviour, Debye-Huckel screening and Bjerrum pairing [4-6]. I will describe experimental results for both traditional spin ice materials (Ho2Ti2O7, Dy2Ti2O7) and a recently discovered system (Dy2Ge2O7).

References:

[1] Bramwell and Gingras, Science, 294 1495 2001 [2] Castelnovo, Moessner & Sondhi, Nature 451 42 (2008) [3] Ryzhkin, JETP 101 481 (2005); [4] Bramwell et al. Nature 461 956 (2009) [5] Fennell et al., & Bramwell Science 326 415 (2009) [6] Giblin, Bramwell et al., Nature Physics 7 252 (2011) [7] Zhou, Bramwell et al., Nat Comm. 478, 1483 (2011)