Quantum phase transition in La1-xBaxTiO3+δ/2:: Evidence from resistivity measurements -: art. no. 165106

The temperature and doping dependence of resistivity (rho) and thermopower (S) of La1-xBaxTiO3+delta/2 have been studied systematically. We observe a quantum phase transition at around x(c)=0.25. Below this critical value of doping, rho shows T-2 dependence due to the electron-electron correlation which is a characteristic feature of Fermi liquid. However, above x(c), rho exhibits T-3/2 behavior. This unusual T-3/2 dependence of rho may be understood on the basis of scattering of the conduction electrons by locally cooperative bond-length fluctuations as observed in other strongly correlated systems. The thermopower is negative and shows almost linear temperature dependence for x < 0.70.