Optically pumped transport in ferromagnet-semiconductor Schottky diodes (invited)

Abstract

Optical pumping is used to generate spin-polarized carriers in epitaxial ferromagnet-GaAs Schottky diodes with In y Ga 1Ϫy As quantum wells placed in the depletion region. A strong dependence of the photocurrent on the polarization state of the incident light is observed, and a series of measurements as a function of excitation energy, bias voltage, magnetic field, and excitation geometry are used to distinguish spin-dependent transport from a variety of background effects. The spin polarization of the photocurrent for pumping energies at and above the band gap of GaAs is of order 0.5% or less. Much larger polarization dependence is observed for excitation energies near the quantum well ground state. Although background effects are very large in this regime, the field dependence of the polarization signal for several samples is suggestive of spin-dependent transport.

Magnetic and structural properties of stoichiometric thin Fe3Si/GaAs(0 0 1) films

“…Experimental work on the 'Spin LED' [1] (electroluminescence), or photoexcitation studies in ferromagnetic Schottky contacts [2,3] constitute examples of the potential afforded by this new field of research. However, it has been argued that in the diffusive regime the main obstacle for detection of spin injection in semiconductor (SC)/ferromagnetic (FM) metal structures is the impedance mismatch between the (high resistance) SC and the (low resistance) FM metal [4].…”

Spin selective transport at the ferromagnetic wire/GaAs interface

“…Spin polarized electron transport across the semiconductor/ferromagnet interface is principally determined by different transmission probabilities for spin-up and spin-down electrons, depending on the relative orientation of the magnetic moments of the ferromagnet and the electron spins in the semiconductor-see Refs. [5][6][7][8][9]. However, the data of spin-dependent photocurrent in a previous report include contributions from other mechanisms such as Zeeman splitting in GaAs due to the application of magnetic fields in excess of 2 T [7].…”

“…[5][6][7][8][9]. However, the data of spin-dependent photocurrent in a previous report include contributions from other mechanisms such as Zeeman splitting in GaAs due to the application of magnetic fields in excess of 2 T [7]. In order to rule out the contribution, the magnetic domain structure of the ferromagnet needs to be controlled at remanence, with a view to revealing the mechanism of spin selective electron transport across the semiconductor/ferromagnet interface.…”

Spintronics for electrical measurement of light polarization

“…We mention that although the principle of operation of our proposal is straightforward, it is different from the existing electrical measurement scheme with a single ferromagnetic contact on top of the semiconductor layer. 19,20 If the contacts are separated by less than the spin diffusion length then the spin accumulation profile in the channel "senses" the antiparallel contacts. Consequently, the difference in the relative current magnitude from each terminal is sharper compared to the difference in photocurrent from a single contact scheme.…”