Electronic transport properties of Pb(Bi_1−xSb_x)₂(Te_1−ySe_y)₄ topological insulator

A series of Pb(Bi1− xSb x)2(Te1− ySe y)4 topological insulator crystals with various Sb molar ratios x and Se molar ratios y were fabricated, and their electronic transport properties were studied. Some of the millimeter-sized samples exhibited metallic behavior, while others exhibited semiconducting behavior with a resistivity as high as 48 mΩ cm at 2 K. In addition, Hall coefficients with a large variance were observed for samples from the same ingot, indicating spatial fluctuations in the composition and/or a nonuniform defect distribution. Then, micrometer-sized samples were cut from the millimeter-sized sample with the highest resistivity, and further electrical transport measurements were performed. Some of the micrometer-sized samples exhibited an even higher resistivity than that for the millimeter-sized sample. The magnetoresistance of the semiconducting micrometer-sized samples agreed well with a three-dimensional weak antilocalization/weak localization model in the low-temperature region below 20 K.