Effects of intercalation on the lattice instability and the superconductivity of NbSe2 and NbS2 are studied in the framework of the rigid band approximation. In the case of doping acceptor-type intercalants into NbSe2, the point of lattice instability in q-space is moved to q = ΓM from q = 2/3 ΓM Further, the frequency renormalization is enhanced and the CDW transition temperature is expected to increase. In the case of doping donor-type intercalants, on the other hand, the frequency renormalization is weakened and the lattice instability is suppressed. The same tendency is found also in NbS2. The effect of intercalation on the superconducting transition temperature Tc of NbS2 is investigated by calculating the functional derivative of Tc with respect to the spectral function. The donor-type intercalant lowers Tc as observed in the case of alkali-metal doping. On the other hand, the acceptor-type intercalant raises Tc as long as the lattice instability does not take place.
ASJC Scopus subject areas
- 化学 (全般)