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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, Y1-xLaxTiO3 (x≤0.25), and Y1-yCayTiO3 (y≤0.35) with the optical traveling-solvent floating-zone technique. 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.
Bibliographical noteFunding Information:
We thank K. Olson for help with the growth of the () crystal and A. Najev for helpful comments on the manuscript. The work at the University of Minnesota was funded by the Department of Energy through the University of Minnesota Center for Quantum Materials, under Grant No. DE-SC0016371. Parts of this work were carried out in the University of Minnesota Characterization Facility, which receives partial support from NSF through the MRSEC program. Electron microprobe analysis of the crystal chemical composition was carried out at the Electron Microprobe Laboratory, Department of Earth Sciences, University of Minnesota–Twin Cities. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. We acknowledge the support of NIST, U.S. Department of Commerce, in providing some of the neutron research facilities used in this work.
© 2021 American Physical Society.