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Title: Spin-injection efficiency and magnetoresistance in a ferromagnet-semiconductor-ferromagnet trilayer
Authors: Agrawal, S.
Jalil, M.B.A. 
Teo, K.L. 
Liew, Y.F.
Issue Date: 15-May-2005
Citation: Agrawal, S., Jalil, M.B.A., Teo, K.L., Liew, Y.F. (2005-05-15). Spin-injection efficiency and magnetoresistance in a ferromagnet-semiconductor-ferromagnet trilayer. Journal of Applied Physics 97 (10) : -. ScholarBank@NUS Repository.
Abstract: We present a drift-diffusion transport model to evaluate the spin-injection efficiency η and magnetoresistance (MR) ratio in a ferromagnetic (FM) metal-semiconductor (SC)-FM metal trilayer structure. This model takes into account the differential interfacial resistances (IR) for spin-up and spin-down electrons and spin relaxation within the SC layer. The electrochemical potential μ for both spin directions is analytically solved and expressions for η, spin polarization of current P, and the MR ratio are derived. The presence of IR at the FM-SC boundary is crucial for generating a large spin splitting of μ, and consequently a high injection efficiency η. The IR needs to fulfill the requirements of (i) of a large magnitude comparable to the resistance of the SC layer and (ii) high asymmetry with respect to the two spin directions. To increase η from 1% to 30%, we require a large IR of 10-5 Ω cm2 and a spin asymmetry of 10:1. There are more stringent requirements for achieving a high MR ratio. An IR of 10-5 Ω cm2 and FM contact polarization Pc of 80% will only yield an MR ratio of 10%. We require a much larger IR ≥ 10-4 Ω cm2 or virtually half-metallic contacts, i.e., Pc of ~100% to achieve high MR ratio exceeding 50%. © 2005 American Institute of Physics.
Source Title: Journal of Applied Physics
ISSN: 00218979
DOI: 10.1063/1.1886886
Appears in Collections:Staff Publications

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