Excitations from a strongly frustrated system, the kagome ice state of the spin ice Dy2Ti2O7 under magnetic fields along a [111] direction, have been studied. They are theoretically proposed to be regarded as magnetic monopoles. Neutron scattering measurements of spin correlations show that close to the critical point the monopoles are fluctuating between high- and low-density states, supporting that the magnetic Coulomb force acts between them. Specific heat measurements show that monopole-pair creation obeys an Arrhenius law, indicating that the density of monopoles can be controlled by temperature and magnetic field.
@article{arxiv.0908.3568,
title = {Observation of Magnetic Monopoles in Spin Ice},
author = {Hiroaki Kadowaki and Naohiro Doi and Yuji Aoki and Yoshikazu Tabata and Taku J. Sato and Jeffrey W. Lynn and Kazuyuki Matsuhira and Zenji Hiroi},
journal= {arXiv preprint arXiv:0908.3568},
year = {2009}
}
Comments
5 pages, 4 figures; International Conference on Neutron Scattering 2009 (May 7); J. Phys. Soc. Jpn. 78, No.10 (2009) (Received Aug 11, 2009; accepted Sept 8, 2009; published Oct 13, 2009)