Ludovic Jaubert MPI-PKS Dresden
Since the discovery of quasi-particles similar to magnetic monopoles in
spin ice [1], many groups have been looking for a signature of their
existence, either direct (measurement of their magnetic charge [2]) or
indirect, through their influence on phase transitions [1], magnetic
dynamics [3] or in the "vacuum" surrounding them, filled with a network of
classical Dirac strings [4,5,6].
In this talk, I will introduce spin ice and endeavor to give a short
overview of this field, while focusing on the collective behaviour of
these quasi-particles. For example, the rarefaction of monopoles at low
temperature leads to non-standard properties in the magnetic
susceptibility and in the relaxation time, as illustrated by neutron
scattering or SQUID experiments on spin ice crystals [2,7].
[1] Castelnovo & al. Nature (2008)
[2] Bramwell & al. Nature (2009)
[3] LJ & Holdsworth, Nature Phys. (2009)
[4] Morris & al. Science (2009)
[5] Fennell & al. Science (2009)
[6] Kadowaki & al. J. Phys. Soc. Jap. (2009)
[7] Snyder & al. Phys. Rev. B (2004)