Quantized anomalous Hall conductance in a bulk dilute Mn-doped topological insulator Bi₂Te₃ at high temperatures

Thus far Quantized anomalous Hall (QAH) has only been realized in the mK range in ultra-thin (5-10nm) MBE films of heavily Cr- or V-doped (Bi,Sb)₂Te₃, where the Curie T_c could be as high as 60 K but the onset of Anomalous Hall effect (AHE) was at a much lower T. Here we report achieving Hall conductance quantization in the Kelvin range in dilute (2%) Mn-doped thick (50-300 nm) single crystals of Bi₂Te₃ by taking a different approach to tune the Fermi level E_F into the Dirac gap. Our technique employs high energy-electron beams (2.5MeV) to create charged defect states in the bulk and thermal annealing protocols to control both E_F and the surface bandstructure_. of the initially n-type Mn-doped Bi₂Te₃. In contrast to previous work, the magnetization M was found to be mean-field-like and carrier independent, with M and AHE onsetting at the same T_c ~ 13 K. We observe conductance quantization G_xy = 1.0098 h/e² not in the bulk gap but on the bulk conduction band where, remarkably, conduction electrons do not contribute to AHE. We will discuss the correlation of surface and bulk AHE with magnetism in this dilute system. The cross-correlation of transport data with STM and ARPES will be discussed.