Field-induced negative differential spin lifetime in silicon
  We show that the electric field-induced thermal asymmetry between the electron and lattice systems in pure silicon substantially impacts the identity of the dominant spin relaxation mechanism. Comparison of empirical results from long-distance spin transport devices with detailed Monte-Carlo simulations confirms a strong spin depolarization beyond what is expected from the standard Elliott-Yafet theory already at low temperatures. The enhanced spin-flip mechanism is attributed to phonon emission processes during which electrons are scattered between conduction band valleys that reside on different crystal axes. This leads to anomalous behavior, where (beyond a critical field) reduction of the transit time between spin-injector and spin-detector is accompanied by a counterintuitive reduction in spin polarization and an apparent negative spin lifetime. 
Jing Li (1), Lan Qing (2), Hanan Dery (2), and Ian Appelbaum (1) ((1)   U. Maryland, (2) U. Rochester)
cond-mat.mtrl-sci cond-mat.other