Heavy-fermion formation at the metal-to-insulator transition in Gd1-xSxTiO3 - art. no. 193103

The perovskitelike transition-metal oxide Gd1-xSrxTiO3 is investigated by m easurements of resistivity, specific-heat, and electron paramagnetic resona nce (EPR). Approaching the metal-to-insulator transition from the metallic regime (x greater than or equal to0.2), the Sommerfeld coefficient gamma of the specific heat becomes strongly enhanced and the resistivity increases quadratically at low temperatures. which both are fingerprints of strong el ectronic correlations. The temperature dependence of the dynamic susceptibi lity, as determined from the Gd3+-EPR linewidth, signals the importance of strong spin fluctuations. as observed in heavy-fermion compounds.