Anisotropic Magnetoresistivity in Semimetal TaSb_2

We investigate the anisotropic magnetic transports in topological semimetal TaSb_2. The compound shows the large magnetoresistance (MR) without saturation and the metal-insulator-like transition no matter whether the magnetic field is parallel to c-axis or a-axis, except that the MR for \boldsymbol B\|c is almost twice as large as that of \boldsymbol B\|a at low temperatures. The adopted Kohler's rule can be obeyed by the MR at distinct temperatures for \boldsymbol B\|c, but it is slightly violated as \boldsymbol B\|a. The angle-dependent MR measurements exhibit the two-fold rotational symmetry below 70 K, consistent with the monoclinic crystal structure of TaSb_2. The dumbbell-like picture of angle-dependent MR in TaSb_2 suggests a strongly anisotropic Fermi surface at low temperatures. However, it finally loses the two-fold symmetry over 70 K, implying a possible topological phase transition at around the temperature where T_\rm m is related to a metal-insulator-like transition under magnetic fields.