Nanocomposites and nanomaterials

Magneto-transport properties of Bi2Se3 whiskers: superconductivity and weak localization
A.Druzhinin, I.Ostrovskii, Yu.Khoverko, N.Liakh-Kaguy,V.Troshina
Department of Semiconductor Electronics, Institute of Telecommunications, Radioelectronics and Electronic Engineering, Lviv Polytechnic National University, Kotliarevskyi Str., 1, Lviv-79013, Ukraine.
E-mail: druzh@polynet.lviv.ua

Studies of topological materials (TM) are very promising for revealing various extraordinary effects such as superconductivity [1], Kondo effect [2], presence of Majorana fermions [3] etc.
Temperature dependencies of Bi2Se3 whiskers’ resistance with Pd doping concentration in the vicinity to metal-insulator transition where measured in temperature range 4.2 – 300 K. At temperature 5.3 K a sharp drop in the whisker resistance was found. The observed effect is likely connected with contribution of two processes such as the electron localization in the whiskers and transition in superconducting state at temperature 5.3 K, which is likely result from Pd complexes.
Transverse magnetoresistance in n-type Bi2Se3 whiskers with different doping concentration in the vicinity to the metal-insulator transition from metal side of the transition was studied in magnetic field 0 - 10 T. The magnetic field suppression of superconductivity allows to determine the main parameters: upper critical magnetic field Bc2 = 1.5 T, superconductor coherence length ξ(0) = 15 nm, superconductive gap   0.8 meV.

1.	Hor Y., Williams A., Checkelsky J., Roushan P., Seo J., Xu Q., Zandbergen H., Yazdani A., Ong N., Cava R. Superconductivity in CuxBi2Se3 and its implications for pairing in the undoped topological insulator // Phys. Rev. Lett.- 2010.-104(5).- P.057001.
2.	Dzero M., Sun K., Galitski V., Coleman P. Topological Kondo Insulators//Phys. Rev. Lett.-2010.- 104.-P.106408.
3.	Wilczek F. Majorana returns// Nature Phys. 5.-2009.- pp.614-618.