LOW-TEMPERATURE ELECTRON-TRANSPORT PROPERTIES OF LA2-XSRXNIO4 WITH 0.5-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1.3

Electrical resistivity (rho) measurements have been carried out on the quasi-two-dimensional oxide La2-xSrxNiO4 (0.5 less-than-or-equal-to x less-than-or-equal-to 1.3) in the temperature (T) range 4.3-300 K. A progressive decrease in resistivity and a change from semiconducting- to metallic-type behavior is observed with increasing Sr content. The rho(T) data of samples in the composition range 0.5 less-than-or-equal-to x less-than-or-equal-to 0. 9 closely follow the Mott variable-range-hopping-type model, whereas samples with x > 1.0 show correlated metallic-type conduction, with a weak upturn in rho(T) at low temperatures. This resistivity upturn follows a T1/2 dependence below approximately 25 K, indicative of electron-electron interaction in a disordered, poorly conducting metallic phase. In the overdoped (x > 1.0) samples a progressive decrease in this upturn indicates a reduction in the electron-electron interaction strength with increasing Sr (hole) content. (C) 1994 Academic Press, Inc.