Anisotropic Electrical Spin Injection in Ferromagnetic Semiconductor   Heterostructures
  A fourteen-fold anisotropy in the spin transport efficiency parallel and perpendicular to the charge transport is observed in a vertically-biased (Ga,Mn)As-based spin-polarized light emitting diode. The spin polarization is determined by measuring the polarization of electroluminescence from an (In,Ga)As quantum well placed a distance d (20 to 420 nm) below the p-type ferromagnetic (Ga,Mn)As contact. In addition, a monotonic increase from 0.5 to 7% in the polarization is measured as d decreases for collection parallel to the growth direction, while the in-plane polarization from the perpendicular direction (~0.5%) remains unchanged. 
D.K. Young (1), E. Johnston-Halperin (1), D.D. Awschalom (1), Y. Ohno   (2), H. Ohno (2) ((1) University of California - San...