Sr-Doping-Level Dependence of Resistivity and Mobility of La_2-xSr_xCuO₄

Abstract

According to the observation of the resistivity measurements of the bulk specimens of La_2-xSr_xCuO₄ (LSCO), the following phenomena have been found. (i) The resistivity, which is dependent on Sr-doping level (x), shows anomalously large decrease around the special doping levels x_??_1/4ⁿ(n_??_1, 2, 3, …) in the temperature range from 4.2 K up to mom temperature. (ii) The superconductivity appears at low temperature in the doping range1/4²_??_x_??_ 1/4. In order to make clear the effect of the normal resistivity depression around the special Sr doping levels, we conducted a Hall measurement on the specimens of LSCO which were in the form of bulk and thin film, and found that the Hall mobility increases around the special doping levels mentioned above.