Frustrated Magnetism in Rare-Earth Titanate Pyrochlore Thin Films Grown by Molecular Beam Epitaxy

Frustrated magnetism generated by the network of corner-sharing tetrahedra in pyrochlores leads to exotic magnetic behavior ranging from unusual ordered phases to quantum spin ice and quantum spin liquid ground states. In thin films, the interactions between magnetic cations can be tuned with epitaxial strain, dilution with non-magnetic ions, and probed by varying film thickness. Thus, the thin film geometry provides fertile ground to examine unusual magnetic properties in ways that are inaccessible to bulk growth techniques. Using reactive-oxide molecular beam epitaxy, we have produced thin films of (111)-oriented Tb₂Ti₂O₇ with high crystalline quality confirmed by in-situ RHEED, x-ray diffraction, and atomic-resolution STEM. We use SQUID magnetometry to study the thickness dependence of magnetic behavior in pure Tb₂Ti₂O₇ films and heterostructures with non-magnetic, isostructural Y₂Ti₂O₇ layers.