Weak antilocalization and two-carrier electrical transport in Bi1−xSbx single crystals (0%≤x≤17.0%)

Experimental investigation of the weak antilocalization (WAL) effect on the Hall resistivity is quite rare, because the WAL is known to have no influence on the Hall effect in a single-band system. We challenge this view in a system that has both electrons and holes by deriving a two-band model modified by the WAL effect and by applying it to the low-field magnetoresistance (MR) and Hall resistance (HR) of $\mathrm{B}{\mathrm{i}}_{1\ensuremath{-}x}\mathrm{S}{\mathrm{b}}_x$ single crystals $(0\ensuremath{\le}x\ensuremath{\le}17.0%)$. Simultaneous occurrence of a dip in MR and nonlinearity in HR suggests that the $\mathrm{B}{\mathrm{i}}_{1\ensuremath{-}x}\mathrm{S}{\mathrm{b}}_x$ is a rare three-dimensional system, in which WAL and two distinct charge carriers interplay. The modified two-band model describes all the main features of MR and HR that are not captured by the conventional theory. From the quantitative analysis based on the modified theory, the values of key parameters, such as carrier density and mobility of electrons and holes, are estimated. The modified two-band model provides a solid framework for understanding electrical transport phenomena of a material with strong spin-orbit interaction and multiple distinct charge carriers.