Thermal induced metal-insulator transition in the titanium oxides single crystals with a high melting point

We have studied the mechanism of a metal-insulator(M-I)transition by the magnetic，transport and thermal measurements of Y I D21-x D 2 Ca I D 2 x D 2 TiO I D 23 D 2(x=0.3-0.4)which exhibits inverse-Mott transition from a metallic state at low temperatures to a semiconducting one at high temperatures.1.Crystal growth and characterization：We have developed the method of growth for Yy D21-x D2Ca D2x D2TiO D23 D2single crystals by using an image furnace.Oxygen contents of samples were determined by thermo-gravimetric analysis(TGA).The results of TGA was used to obtain the best conditions for annealing under flowing oxygen.2。High-resolution photoemission spectroscopy：We have observed a clear M-I transition in the temperature-dependent photoemission spectra for x=0.39consistent with transport measurements.3。Spin-charge separation：In a M-1 transition region，the significant difference in temperature dependences exist between magnetic.susceptibility and electrical resistivity。For a sample in the ferromagnetic region(x=0.05)，we have found the stability of an orbital-ordered state a-s for x=0 by spin-polarized neutron diffraction.4。Future plans：Correlations among the charge，s pin and orbital in Y-y D21-x-D-2 Ca-D 2 x-D 2 TiO-D 23-D 2 will be studied by the X-ray diffraction using synchrotron radiation and the spin-polarized neutron diffraction.

We have studied the mechanism of a metal-insulator (M-I) transition by the magnetic, transport and thermal measurements of YィイD21-xィエD2CaィイD2xィエD2TiOィイD23ィエD2 (x=0.3〜0.4) which exhibits inverse-Mott transition from a metallic state at low temperatures to a semiconducting one at high temperatures.1. Crystal growth and characterization: We have developed the method of growth for YィイD21-xィエD2CaィイD2xィエD2TiOィイD23ィエD2 single crystals by using an image furnace. Oxygen contents of samples were determined by thermo-gravimetric analysis(TGA) . The results of TGA was used to obtain the best conditions for annealing under flowing oxygen.2. High-resolution photoemission spectroscopy : We have observed a clear M-I transition in the temperature-dependent photoemission spectra for x=0.39 consistent with transport measurements.3. Spin-charge separation : In a M-1 transition region, the significant difference in temperature dependences exist between magnetic .susceptibility and electrical resistivity. For a sample in the ferromagnetic region (x=0.05), we have found the stability of an orbital-ordered state a-s for x=0 by spin-polarized neutron diffraction.4. Future plans : Correlations among the charge , s pin and orbital in YィイD21-xィエD2CaィイD2xィエD2TiOィイD23ィエD2 will be studied by the X-ray diffraction using synchrotron radiation and the spin-polarized neutron diffraction.