Spin Dynamics in Bi2Se3 / GaAs Heterostructures

The narrow band gap semiconductor Bi$_2$Se$_3$ has been characterized as a topological insulator (TI), wherein strong spin-orbit coupling and time-reversal symmetry give rise to spin-polarized surface conduction states. Molecular beam epitaxy (MBE) of Bi$_2$Se$_3$ thin films onto conventional semiconductors such as GaAs [1] provides an attractive pathway for the creation of hybrid devices, coupling the exotic spin physics of TIs with the well-understood properties of spin coherence in semiconductors. We employ spatio-temporally resolved optoelectronic techniques to probe the carrier spin dynamics at the heterointerface between a TI and GaAs. Results are compared with interface band structure calculations.\\[4pt] This work is supported by ONR and NSF. \\[4pt] [1] A.~Richardella, D.~M.~Zhang, J.~S.~Lee, A.~Koser, D.~W.~Rench, A.~L.~Yeats, B.~B.~Buckley, D.~D.~Awschalom and N.~Samarth, {\it Appl.~Phys.~Lett.} {\bf 97}, 262104 (2010).