Gingras

//Michel Gingras (University of Waterloo)//
There exist a fair number of insulating magnetic materials where the magnetic species is a 4f (rare-earth) element and which have been long known to display interesting and intriguing magnetic and thermodynamic behaviors. Examples include the three-dimensional Gd3Ga5O12 garnet (GGG) lattice of corner-sharing tetrahedra, the LiHo_xY_{1-x}F4 Ising material in a transverse magnetic field (TFIM), and a number of pyrochlore systems such as the Tb2Ti2O7 spin liquid, the spin Dy2Ti2O7 and Ho2Ti2O7 spin ices and the Gd2(Ti,Sn)2O7 long-range ordered systems. In this talk, I will review some of the problems motivated by experiments on these systems, discuss tentative explanations of what is maybe going on and emphasize what we do not understand.

References:

Gd3Ga5O12 (GGG): Phys. Rev. Lett. **97**, 267203 (2006). http://link.aps.org/abstract/PRL/v97/e267203 LiHo_xY_{1-x}F4 (TFIM): Phys. Rev. Lett. **97**, 237203 (2006). http://link.aps.org/abstract/PRL/v97/e237203 Gd2Sn2O7 (long range order): Phys. Rev. Lett. **99**, 097201 (2007). http://link.aps.org/abstract/PRL/v99/e097201 Tb2Ti2O7 (spin liquid): Phys. Rev. Lett. **98**, 157204 (2007). http://link.aps.org/abstract/PRL/v98/e157204 (Dy/Ho)2Ti2O7 (correlations in spin ice): Phys. Rev. B **70**, 134408 (2004). http://link.aps.org/abstract/PRB/v70/e134408 and http://arxiv.org/abs/0707.3477