Magnetic monopoles in spin ice

✍ Scribed by Castelnovo, C.; Moessner, R.; Sondhi, S. L.

• Book ID: 109897126
• Publisher: Nature Publishing Group
• Year: 2008
• Tongue: English
• Weight: 467 KB
• Volume: 451
• Category: Article
• ISSN: 0028-0836
• DOI: 10.1038/nature06433

✦ Synopsis

Electrically charged particles, such as the electron, are ubiquitous. In contrast, no elementary particles with a net magnetic charge have ever been observed, despite intensive and prolonged searches (see ref. 1 for example). We pursue an alternative strategy, namely that of realizing them not as elementary but rather as emergent particles-that is, as manifestations of the correlations present in a strongly interacting many-body system. The most prominent examples of emergent quasiparticles are the ones with fractional electric charge e/3 in quantum Hall physics. Here we propose that magnetic monopoles emerge in a class of exotic magnets known collectively as spin ice: the dipole moment of the underlying electronic degrees of freedom fractionalises into monopoles. This would account for a mysterious phase transition observed experimentally in spin ice in a magnetic field, which is a liquid-gas transition of the magnetic monopoles. These monopoles can also be detected by other means, for example, in an experiment modelled after the Stanford magnetic monopole search.