Synthesis of and mesoscopic charge transport in magnetically-doped Bi$_{2}$Se$_{3}$ nanoribbons

A simple band structure and a large bulk band gap have allowed Bi$_{2}$Se$_{3}$ to become a reference material for the newly discovered three-dimensional topological insulators, which exhibit topologically-protected conducting surface states that reside inside the bulk band gap. Theoretically, introducing magnetic impurities in Bi$_{2}$Se$_{3}$ is predicted to open a small gap in the surface states by breaking the time-reversal symmetry. We present synthesis of magnetically doped Bi$_{2}$Se$_{3}$ nanoribbons using the vapor-liquid-solid growth method. Studying Bi$_{2}$Se$_{3}$ in nanostructures is useful because of the high surface-to-volume ratio. Low-temperature magneto-transport measurements in the mesoscopic regime show clear differences between the undoped and doped Bi$_{2}$Se$_{3}$ nanoribbons, confirming the presence of magnetic impurities in the Bi$_{2}$Se$_{3}$ nanoribbons.