Spatial imaging of the spin Hall effect and current-induced polarization in two-dimensional electron gases

Spin–orbit coupling in semiconductors relates the spin of an electron to its momentum, and provides a pathway for electrically initializing and manipulating electron spins for applications in spintronics1 and spin-based quantum information processing2. This coupling can be regulated with quantum confinement in semiconductor heterostructures through band-structure engineering. Here we investigate the spin Hall effect3,4 and current-induced spin polarization5,6 in a two-dimensional electron gas confined in (110) AlGaAs quantum wells using Kerr rotation microscopy. In contrast to previous measurements7,8,9,10, the spin Hall profile shows complex structure and the current-induced spin polarization is out-of-plane. The experiments map the strong dependence of the current-induced spin polarization to the crystal axis along which the electric field is applied, reflecting the anisotropy of the spin–orbit interaction. These results reveal opportunities for tuning a spin source using quantum confinement and device engineering in non-magnetic materials.

[1]  Jeremy J. Baumberg,et al.  OPTICAL SPIN RESONANCE AND TRANSVERSE SPIN RELAXATION IN MAGNETIC SEMICONDUCTOR QUANTUM WELLS , 1997 .

[2]  Hideo Ohno,et al.  SPIN RELAXATION IN GAAS(110) QUANTUM WELLS , 1999 .

[3]  Shuichi Murakami,et al.  Dissipationless Quantum Spin Current at Room Temperature , 2003, Science.

[4]  Michel Dyakonov,et al.  Spin Orientation of Electrons Associated with the Interband Absorption of Light in Semiconductors , 1971 .

[5]  D. D. Awschalom,et al.  Observation of the Spin Hall Effect in Semiconductors , 2004, Science.

[6]  E. Rashba,et al.  Oscillatory effects and the magnetic susceptibility of carriers in inversion layers , 1984 .

[7]  V. M. Edelstein.  Spin polarization of conduction electrons induced by electric current in two-dimensional asymmetric electron systems , 1990 .

[8]  H. L. Stormer,et al.  Formation of a high quality two-dimensional electron gas on cleaved GaAs , 1990 .

[9]  V. A. Khablo,et al.  Nuclear electric resonance and orientation of carrier spins by an electric field , 1989 .

[10]  Michel Dyakonov,et al.  Possibility of Orienting Electron Spins with Current , 1971 .

[11]  Spin orientation and spin precession in inversion-asymmetric quasi-two-dimensional electron systems , 2003, cond-mat/0305315.

[12]  Dimitrie Culcer,et al.  Universal intrinsic spin Hall effect. , 2004, Physical review letters.

[13]  J. Hirsch.  Spin Hall Effect , 1999, cond-mat/9906160.

[14]  A. Gossard,et al.  Current-induced spin polarization in strained semiconductors. , 2004, Physical review letters.

[15]  G. Dresselhaus.  Spin-Orbit Coupling Effects in Zinc Blende Structures , 1955 .

[16]  Spin splitting and spin current in strained bulk semiconductors , 2004, cond-mat/0408442.

[17]  Hideaki Takayanagi,et al.  Gate Control of Spin-Orbit Interaction in an Inverted In0 , 1997 .

[18]  D. Awschalom,et al.  Semiconductor spintronics and quantum computation , 2002 .

[19]  D. D. Awschalom,et al.  Coherent spin manipulation without magnetic fields in strained semiconductors , 2004, Nature.

[20]  A. Gossard,et al.  Electrical initialization and manipulation of electron spins in an L-shaped strained n-InGaAs channe , 2005, cond-mat/0502627.

[21]  Stuart A. Wolf,et al.  Spintronics: A Spin-Based Electronics Vision for the Future , 2001, Science.

[22]  Jairo Sinova,et al.  Experimental observation of the spin-Hall effect in a two-dimensional spin-orbit coupled semiconductor system. , 2005 .

[23]  D. D. Awschalom,et al.  Control of electron-spin coherence using Landau level quantization in a two-dimensional electron gas , 2004 .

[24]  Dissipation effects in spin-Hall transport of electrons and holes , 2003, cond-mat/0310108.

[25]  R. Hey,et al.  Current-induced spin polarization at a single heterojunction , 2004 .