Research Project
Grant-in-Aid for Scientific Research (C)
This research focuses on studying phase transitions associated with charge and orbital ordering by means of x-ray scattering in a magnetic field or under high pressure. Main results are as follows.1.Structural changes through an insulator-metal transition induced by a magnetic field have been investigated in a perovskite-type manganese oxide Eu_<0.6>Sr_<0.4>MnO_3 by x-ray diffraction. The change in the Mn-O-Mn bond angle through the transition qualitatively agrees with the double exchange mechanism. The pressure effect was also studied in a compound exhibiting the charge and orbital ordering. Pressure-induced phase transition to a disordered phase was found. In addition, an indication of the transition to a different type of the charge and orbital ordering was found.2.X-ray powder diffraction experiments using synchrotron radiation were conducted in a mixed valence system of Fe_2BO_4. The structural properties associated with the charge ordering were analyzed by the Rietveld method.3.The electrical resistivity of RNiC_2 compounds, where R is rare-earth, shows anomalous temperature dependences. A set of satellite reflections was found below the metal-insulator transition temperature. This result suggests that the charge density wave is developed below the transition temperature.4.X-ray intensity fluctuation spectroscopy experiments using coherent x-rays were carried out at SPring-8. Speckle patterns were observed in a sample exhibiting an order-disorder transition.5.X-ray diffraction experiments under high magnetic fields using synchrotron radiation (SPring-8) have been performed in low-dimensional systems and materials with multipole order.
All 2005 2004 2003 Other
All Journal Article (34 results) Publications (3 results)
Journal of the Physical Society of Japan 74
Pages: 2301-2309
110001979709
Pages: 2201-2204
110001979691
Journal of the Physical : Condensed Matter 17
Pages: 1598-1601
J.Phys.Soc.Jpn. 74
J.Phys.Cond.Matter 17
Journal of Physics : Condensed Matter 17
Europhysics Letters 68
Pages: 671-677
Journal of the Physical Society of Japan 73
Pages: 3059-3063
110001979256
Pages: 2790-2794
110001979206
Pages: 2650-2653
110001979185
Physical Review B 69
Pages: 220409-220409
PHYSICA B 345
Pages: 78-81
Journal of the Physical : Condensed Matter 16
Journal of Magnetism and Magnetic Materials 272-276
Pages: 424-425
J.Phys.Soc.Jpn. 73
Phys.Rev.B 69
PHYSICA B 346
Pages: 11-14
J.Phys.Condensed Mat. 16
J.Mag.Mag.Mat. 272-276
Spring-8 Research Frontiers 2003
Pages: 50-51
SPring-8 Research Frontiers 2003