(Microsoft PowerPoint - Acad\351mie_08.ppt [Lecture seule])

Spin injection/extraction at a NM/FM interface (beyond ballistic range)NMSpin accumulation∆µ= E -E F↑ F↓zone of spinaccumulationNMl sfEE F↑FMl sfFM= spin↑ chemical potential(illustration in the simplestcase = flat band, low current,no interface resistance,single polarity)F Mls f = spin diffusion length in FMl s fN M= spin diffusion length in NM(example: 0.5 µm in Cu,>10µm in carbonnanotube)E -E F↑ F↓ ~ exp(z/ F Ml ) in FMs fzE F↑E F↓= spin↓ chemical potentialE -E F↑ F↓ ~ exp(-z/ N Ml ) in NMs fSpin current= J ↑ -J ↓N Ml s fFMl sfJ ↑ -J ↓J ↑ +J ↓= current spin polarizationz