Electrical Detection Of Spin Accumulation Research Articles

Nonlinear Electrical Spin Conversion in a Biased Ferromagnetic Tunnel Contact

The electrical detection of spin accumulation in nonmagnetic materials is required for the operation of many spintronic devices. Typically, detection is achieved via a tunnel contact with a ferromagnetic electrode. Spin conversion in a magnetic tunnel contact is conventionally described using linear transport equations---but here the authors demonstrate that electrical spin detection in a biased ferromagnetic tunnel contact is inherently $n\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}r$. This explains a multitude of puzzling spin-transport data, including two-terminal magnetoresistance data, and truly changes our view of spintronic device physics.

Bias current dependence of spin accumulation signals in a silicon channel detected by a Schottky tunnel contact

We study the electrical detection of spin accumulation at a ferromagnet-silicon interface, which can be verified by measuring a Hanle effect in three-terminal lateral devices. The device structures used consist of a semiconducting Si channel and a Schottky tunnel contact. In a low current-bias region, the Hanle-effect curves are observed only under forward bias conditions. This can be considered that the electrical detectability at the forward-biased contact is higher than that at the reverse-biased contact. This is possible evidence for the detection of spin-polarized electrons created in a Si channel.

Electrical detection of spin accumulation in a p-type GaAs quantum well.

We report on experiments in which a spin-polarized current is injected from a GaMnAs ferromagnetic electrode into a GaAs layer through an AlAs barrier. The resulting spin polarization in GaAs is detected by measuring how the tunneling current, to a second GaMnAs ferromagnetic electrode, depends on the orientation of its magnetization. Our results can be accounted for by sequential tunneling with the nonrelaxed spin splitting of the chemical potential, that is, spin accumulation, in GaAs. We discuss the conditions on the hole spin relaxation time in GaAs that are required to obtain the large effects we observe.

Electrical detection of spin accumulation and spin precession at room temperature in metallic spin valves

We have fabricated a multiterminal lateral mesoscopic metallic spin valve demonstrating spin precession at room temperature (RT), using tunnel barriers in combination with metallic ferromagnetic electrodes as a spin injector and detector. The observed modulation of the output signal due to the spin precession is discussed and explained in terms of a time-of-flight experiment of electrons in a diffusive conductor. The obtained spin relaxation length λsf=500 nm in an aluminum strip will make detailed studies of spin dependent transport phenomena possible and allow one to explore the possibilities of the electron spin for new electronic applications at RT.