Magnetic Field Modulated Weak Localization and Antilocalization State in Bi 2 (Te x Se 1− x ) 3 Films

The magneto‐transport properties of a series of Bi 2 (Te x Se 1− x ) 3 films are investigated. It is seen that the doped samples develop an insulating behavior at low temperatures upon the increasing doping level as compared to the pristine sample Bi 2 Se 3 . The field evolution of the magneto‐resistance (MR) under perpendicular and parallel magnetic fields for Bi 2 (Te x Se 1− x ) 3 films with x  = 0, 0.1, 0.24, 0.4, and 0.6 at temperatures from 2 to 200 K is investigated. A low field cusp behavior appears in MR data of Bi 2 (Te 0.1 Se 0.9 ) 3 film, which is associated with the weak anti‐localization (WAL). In Bi 2 (Te 0.4 Se 0.6 ) 3 films, MR with perpendicular and parallel magnetic fields shows signatures of WAL at low magnetic fields. A remarkable negative behavior, similar to weak localization (WL), under a high magnetic field parallel to the film surface is found which is dominated by bulk‐state electrons. MR of Bi 2 (Te 0.6 Se 0.4 ) 3 film reveals a low‐field WAL behavior and a high‐field parabolic behavior, revealing a two‐dimensional magneto‐transport property.