Exchange-driven magnetoresistance in silicon facilitated by electrical   spin injection
  We use electrical spin injection to probe exchange interactions in phosphorus doped silicon (Si:P). The detection is enabled by a magnetoresistance effect that demonstrates the efficiency of exchange in imprinting spin information from the magnetic lead onto the localized moments in the Si:P region. A unique Lorentzian-shaped signal existing only at low temperatures ($\lesssim 25 K$) is observed experimentally and analyzed theoretically in electrical Hanle effect measurement. It stems from spin-dependent scattering of electrons by neutral impurities in Si:P. The shape of this signal is not directly related to spin relaxation but to exchange interaction between spin-polarized electrons that are localized on adjacent impurities. 
Yuichiro Ando, Lan Qing, Yang Song, Shinya Yamada, Kenji Kasahara,   Kentarou Sawano, Masanobu Miyao, Hanan Dery, Kohei Hamaya
cond-mat.mtrl-sci cond-mat.mes-hall