Electronic correlations on the verge of the Mott transition in La1-xSrxTiO3 by Ti-47/49 and La-139 nuclear magnetic resonance

Carrier-doping effects on electronic correlations on the verge of the Mott transition in La1-xSrxTiO3 have been investigated by Ti-47/49 and La-139 NM R. In antiferromagnetic (AF) insulator of LaTiO3 with TN = 140 K, we observ ed zero-field Ti NMR and determine the hyperfine field of 91.4 kOe for Ti n uclei. The increases of nuclear spin-lattice relaxation rates (T-1)(-1) of La and Ti show that effective carrier mass is enhanced critically as the Mo tt transition boundary is approached from the metallic side. We have no evi dence for a prominent increase of AF spin fluctuations at q similar to Q ne ar the Mott transition boundary. Together with the temperature dependence o f T-1 (The Korringa relations of T1T=const are observed for La and Ti) in t he metallic state, we conclude that the AF spin fluctuations of Ti-3d spins due to the interatomic electronic correlations is not important, but singl e-site (intraband) electronic correlations play an important role in drivin g the metal-insulator transition in La1-xSrxTiO3, as opposed to the case of high-T-c cuprates. [S0163-1829(99)13415-5].