Neutron Investigations of Thin Film Ho₂Ti₂O₇

The spin-ice Ho₂Ti₂O₇ has been the subject of study [1-2] for several years as a magnetic analogue of the water ice system. Excitations in this material have been found to map onto magnetic monopoles[3]. Recently, groups have started to explore the effects of strain [4-5] on this system by growing the material in thin film form. They found that at low temperatures, strain allowed the spin ice to fully order at low temperatures. We have recently investigated these films through neutron diffraction measurements performed on the SPINS, BT-7, and MACS instruments at the NCNR. We couple these diffraction studies with capacitive torque magnetometry measurements to explore the effects of size on the magnetic ordering in these materials.

[1] M.J. Harris et al., Phys. Rev. Lett. 79, 2554 (1997)
[2] S.T. Bramwell et al., Phys. Rev. Lett. 87, 047205 (2001)
[3] C. Castelnovo et al., Nature 451,42 (2008)
[4] L. Bovo et al., Nature Comm. 5, 1 (2014)
[5] D.P. Leusink et al., APL Mat. 2, 032101 (2014)