題目 Structural and Electronic Properties of the Spin-Peierls Compound TiOCl



講師　 Dr. Markus Hoinkis

　　　(Osaka University / University of Augsburg, Germany）

日時 9月28日(木) 14:00-15:00

場所 理 C212 会議室



アブストラクト：

The layered Mott insulator TiOCl, which is in a 3d¹ configuration and exhibits two

successive phase transitions, was interpreted as a spin-Peierls system on the basis

of magnetic susceptibility data. After the discovery of the spin-Peierls compound

CuGeO₃, TiOCl is only the second known inorganic material to exhibit this

instability, with record-high transition temperatures of T_c1=67K and T_c2=91K.

The results of x-ray diffraction experiments will be presented that resolve the

dimerization in the low-temperature phase accompanying the spin-Peierls transition

and reveal the nature of the intermediate phase as characterized by an

incommensurate superstructure. The normal-state electronic structure was

investigated by means of angle-resolved and polarization-dependent photoemission

experiments, focusing on the dimensionality and on the orbital character of the

low-lying electronic states. The measured spectral function will be compared to

various DFT and model calculations. A comparison of TiOCl with the isostructural

compound TiOBr shows that multi-band effects and/or the magnetic interchain

interaction on the triangular lattice have to be taken into account in order to arrive

at a realistic theoretic modeling of this system. Finally, a pressure-induced

insulator-metal transition evidenced by means of optical spectroscopy will be

discussed, fueling the speculations of possible RVB physics in the quantum

magnet TiOCl.



担当： 木村昭夫（7471）



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