Indications of the topological transport by the universal conductance   fluctuations in the Bi2Te2Se microflakes
  Universal conductance fluctuations (UCFs) are extracted in the magnetoresistance responses in the bulk-insulating Bi2Te2Se microflakes. Its two-dimensional character is demonstrated by the field-tilting magnetoresistance measurements. Its origin from the surface electrons is determined by the fact that the UCF amplitudes keep unchanged while applying an in-plane field to suppress the coherence of bulk electrons. After considering the ensemble average in a batch of micrometer-sized samples, the intrinsic UCF magnitudes of over 0.37 e2/h is obtained. This agrees with the theoretical prediction on topological surface states. All the evidence point to the successful observation of the UCF of topological surface states. 
Zhaoguo Li, Yuze Meng, Jian Pan, Taishi Chen, Xiaochen Hong, Shiyan   Li, Xuefeng Wang, Fengqi Song, Baigeng Wang
cond-mat.mes-hall