Speaker
Description
Compounds of the form $\rm{A}_2\rm{X}_2\rm{O}_7$ with the pyrochlore structures can exhibit classical or quantum spin ice behaviour if the crystal field environment of the $\rm{A}\rm{O}_8$ arrangement leads to the [111] easy-axis anisotropy. When Pr occupies the A-site, there is a low-lying electronic doublet and $\rm{Pr}_2\rm{X}_2\rm{O}_7$ compounds are found to be quantum spin ices$^1$. Pr$^{3+}$ is a non-Kramers ion and the presence of the muon can distort nearby $\rm{PrO}_8$ units and split the doublet ground states$^2$, resulting in an enhancement of the Pr nuclear moment due to hyperfine coupling with the electronic moments$^3$. We explore this effect using a theoretical model that takes account of the important interactions and compare our simulations with $\mu$SR data on samples of $\rm{Pr}_2\rm{X}_2\rm{O}_7$ (X = Sn, Hf, Zr) and new experimental data on $\rm{Pr}_2\rm{ScTaO}_7$, a candidate system that simultaneously realises spin ice and charge ice structures.
References:
1. A. Princep, Phys. Rev. B 88, 104421 (2013)
2. F. Foronda et al., Phys. Rev. Lett. 114, 017602 (2015)
3. B. Bleaney, Physica 69, 317 (1973)
