Structural and Galvanomagnetic properties in Mn-Bi2Te3 thin films

Abstract

Bismuth-based binary chalcogenide compounds such as Bi2Te3 and Bi2Se3 are well known materials for their excellent thermoelectric properties due to their near-gap electronic structure. In the last few years these materials have received attention for exhibiting new physics of 3D topological insulators (TI). Possible applications of TI based devices range from quantum computing, spin based logic and memory to electrodynamics. The 3D TIs present spin-momentum-locked surface states by time reversal symmetry (TRS). Introducing magnetic doping in a TI, brakes the TRS and is predicted to open the gap at Dirac point, resulting in exotic quantum phenomena. This interaction between magnetism and topologically protected states is of potential attention for applications in modern spintronics. Quantum phenomena such as weak antilocalization observed in these nanostructures are described. In this work, granular Mn-Bi2Te3 thin films were grown by DC magnetron sputtering on Si(111) substrates and were submitted to ex situ annealing. We present results for the crystal structure of sputtered and annealed films characterized with X-ray diffraction and high-resolution scanning electron microscopy (HRSEM). The surface analysis was studied with atomic force microscopy (AFM). Magnetotransport measurements were performed using standard four probe technique with Hall and MR configurations, with perpendicular magnetic fields up to 9T and temperatures from 300 to 3K.