Theory of electrical spin-detection at a ferromagnet/semiconductor interface

Abstract

We present a theoretical model that describes electrical spin-detection at a ferromagnet/semiconductor interface. We show that the sensitivity of the spin detector has strong bias dependence which, in the general case, is dramatically different from that of the tunneling current spin polarization. We show that this bias dependence originates from two distinct physical mechanisms: 1) the bias dependence of tunneling current spin polarization, which is of microscopic origin and depends on the specific properties of the interface, and 2) the macroscopic electron spin transport properties in the semiconductor. Numerical results show that the magnitude of the voltage signal can be tuned over a wide range from the second effect which suggests a universal method for enhancing electrical spin-detection sensitivity in ferromagnet/semiconductor tunnel contacts. Using first-principles calculations we examine the particular case of a Fe/GaAs Schottky tunnel barrier and find very good agreement with experiment. We also predict the bias dependence of the voltage signal for a Fe/MgO/GaAs tunnel structure spin detector.

9 pages, 5 figures

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Cited by in corpus (7)

• Spin injection and detection up to room temperature in Heusler~alloy/$n$-GaAs spin valves
• Bias-controlled sensitivity of ferromagnet/semiconductor electrical spin detectors
• Gate-tunable large magnetoresistance in an all-semiconductor spin-transistor-like device
• Temperature evolution of spin accumulation detected electrically in a nondegenerated silicon channel
• The effect of spin drift on spin accumulation voltages in highly-doped Si
• Giant enhancement of spin detection sensitivity in (Ga,Mn)As/GaAs Esaki diodes
• Nonmonotonic bias dependence of local spin accumulation signals in ferromagnet/semiconductor lateral spin-valve devices