Recently, a research group of High magnetic field laboratory, Chinese Academy of Sciences(CHMFL) head by Prof. TIAN mingliang has made a series progresses in the investigation of surface states in one-dimensional topological insulator nanowires.
Scientists carried out a systematic comparative study on the cylindrical single-crystal Bi2Te3 nanowires of various diameters and found that the amplitude of the quantum oscillation becomes much stronger as the metallic surface states are enhanced for thinner nanowires. In the study, both the predicted Aharonov-Bohm quantum oscillations and SdH oscillations are observed. These data provide clear evidence of coexistence of the nontrivial topological Dirac state and trivial electron state on the surface of Tl nanowires.
Meanwhile, they found that the Angle-dependent magnetoconductance of these nanowires in low field regime can be well described by one-dimensional (1D) weak antilocalization (WAL) model, where the dephasing length of the electrons follows T-1/3 dependence but insensitive to the wire diameter. Meanwhile, such a 1D surface WAL was found to be enhanced significantly with the decrease of the wire diameter.
These discoveries open a new avenue to understand the evolutions of surface states in one-dimensional scale and explore the Majorana fermions in heterostructure of topological insulator nanowires and conventional superconductor.The above works were published on Scientific Reports respectively.
Figure 1 SEM and TEM images and quantum oscillations of Bi2Te3 nanowires with diameter of 50 nm. The observation of two kinds of oscillations provide clear evidence of coexistence of the nontrivial topological Dirac state and trivial electron state on the surface of topological insulator nanowires.
Figure 2 The angle-dependent magnetoconductance of Bi2Te3 nanowires with diameter of 300 nm, 100 nm and 50 nm. The solid red lines are the fit with one-dimensional localization theory. All the traces were normalized to a single curve in low field range, indicating the surface nature of the magnetoconductance.
CONTACT: Prof.Tian Mingliang
High Magnetic Field Laboratory, Chinese Academy of Sciences
Email: tianml@hmfl.ac.cn
Appendix:
One-dimensional weak antilocalization in single-crystal Bi2Te3 nanowires
（http://www.nature.com/srep/2013/130328/srep01564/full/srep01564.html）
Dual evidence of surface Dirac states in thin cylindrical topological insulator Bi2Te3 nanowires
(http://www.nature.com/srep/2013/130206/srep01212/full/srep01212.html)
