Growth and characterization of large (Y,La)TiO3 and (Y,Ca)TiO3 single crystals

• Published in: Physical review materials 2021-12, Vol.5 (12)
• Main Authors: Hameed, S., Joe, J., Thoutam, L. R., Garcia-Barriocanal, J., Yu, B., Yu, G., Chi, S., Hong, T., Williams, T. J., Freeland, J. W., Gehring, P. M., Xu, Z., Matsuda, M., Jalan, B., Greven, M.
• Format: Article
• Language: English
• Subjects: crystal growth; MATERIALS SCIENCE; metal-insulator transition; Mott insulators; neutron scattering; perovskites; transition metal oxides; x-ray absorption spectroscopy
• ISSN: 2475-9953; 2475-9953
• DOI: 10.1103/PhysRevMaterials.5.125003

The Mott-insulating rare-earth titanates ( RTiO3 , with R being a rare-earth ion) are an important class of materials that encompasses interesting spin-orbital phases as well as ferromagnet-antiferromagnet and insulator-metal transitions. The growth of these materials has been plagued by difficulties related to overoxidation, which arises from a strong tendency of Ti3+ to oxidize to Ti4+ . We describe our efforts to grow sizable single crystals of YTiO3, Y 1-xLaxTiO3 ( x≤0.25 ), and Y 1-yCayTiO3 ( y≤0.35 ) with the optical traveling-solvent floating-zone technique. Finally, we present sample characterization via chemical composition analysis, magnetometry, charge transport, neutron scattering, x-ray absorption spectroscopy, and x-ray magnetic circular dichroism to understand macroscopic physical property variations associated with overoxidation. Furthermore, we demonstrate a good signal-to-noise ratio in inelastic magnetic neutron scattering measurements of spin-wave excitations. A superconducting impurity phase, found to appear in Ca-doped samples at high doping levels, is identified as TiO.