Tuning Epitaxial Strain in XY Pyrochlore Er₂Ti₂O₇

Tuning parameters in frustrated magnetism allow us to explore the complex landscape of magnetically fragile ground states. In epitaxial thin film samples, we can study the statespace of eptiaxial strain (caused by the lattice mismatch between substrate and film) and the reduced dimensionailty inherent to a thin film. Thin film works on frustrated titanate pyrochlores have focused on spin ice compounds (Ho₂Ti₂O₇ and Dy₂Ti₂O₇)^[1-3] and the unconventional magnetic ground state of Tb₂Ti₂O₇^[4]. This study examines the ordered magnetic ground state of Er₂Ti₂O₇. The ground state selection between the Ψ₂ and Ψ₃ basis states of the Γ₅ manifold and the relative stability of Γ₅ to Palmer-chalker configurations have been shown to be sensitive to a number of tuning parameters such as magnetic dilution and isovalent non-magnetic substitution. By fabricating films of different thicknesses using pulsed-laser deposition, we tune the epitaxial strain on the magnetic lattice, and examine the subsequent magnetic groundstate through bulk characterization and neutron scattering.

[1] L. Bovo et al., Nat. Communications 5, 3439 (2014)
[2] D. P. Leusink et al., APL Materials 2.3, 032101 (2014)
[3] Barry et al. arXiv:1805.06565 (2018)
[4] L. Bovo et al., Nanotechnology 28.5, 055708 (2016)