非化学量論的TiS₂相の電気的，磁気的特性

抄録

Measurements of electric resistivity, Hall coefficient and magnetic susceptibility was carried out for various compositions in the nonstoichiometric TiS₂ phase over the temperature range of 4.2°K to 300°K.
From the behaviours on the temperature dependence of electric conductivity measured for single crystals with Ti-concentrations from TiS_2.00 to TiS_1.94, it is suggested that (i) the metallic conductivity in the stoichiometric composition TiS_2.00 comes from a slight over-lapping between the bottom of conduction band and the top of valence band, (ii) the Fermi level of TiS_2.00 is in the vicinity of a minimum position of the density of states curve N(E) resulting from the overlap of bands, and (iii) the Fermi levels for compositions with excess Ti deviate from the minimum position to high energies with the increase in excess Ti.
Magnetic susceptibilities were observed over the composition range from TiS_2.00 to TiS_1.82. They are paramagnetic and their temperature dependence is extremely small. The Pauli paramagnetism of the conduction electron gas contributes mainly to the magnetism of the TiS₂ phase. From the relation between the observed magnetic susceptibilities and concentrations of excess Ti, it is concluded that the Fermi levels for compositions near the stoichiometric TiS_2.00 are in the neighbourhood of the minimum position of the N(E) curve, but in a range of Ti concentrations higher than TiS_1.90 the Fermi level deviates from the top of valence band, and hence the density of states is approximeted by a relation N(E)∝E^1⁄2.