Abstract
In the absent of magnetic field, we have observed the anisotropic spin polarization degree of photoconduction (SPD-PC) in (Ga,Mn)As/GaAs heterojunction. We think three kinds of mechanisms contribute to the magnetic related signal, (i) (Ga,Mn)As self-producing due to the valence band polarization, (ii) unequal intensity of left and right circularly polarized light reaching to GaAs layer to excite unequal spin polarized carriers in GaAs layer, and (iii) (Ga,Mn)As as the spin filter layer for spin transport from GaAs to (Ga,Mn)As. Different from the previous experiments, the influence coming from the Zeeman splitting induced by an external magnetic field can be avoided here. While temperature dependence experiment indicates that the SPD-PC is mixed with the magnetic uncorrelated signals, which may come from current induced spin polarization.
Highlights
Diluted magnetic semiconductors(DMS) have long been of great interest in combining the optical character of semiconductor and the magnetism character of ferromagnetic material1–4. (Ga,Mn)As is considered as one of the most promising DMS for spintronic devices due to the compatible growth techniques and relatively high Curie temperature[5,6]
We present the azimuth angle and the incident angle dependence of the spin polarization degree of photoconduction (SPD-PC), and find optical control of similar giant magneto resistance (GMR) effect
Assuming the photoconduction is proportional to the absorption, the SPD-PC should be expressed as Δσs/σ0 ∝cos α sin θ
Summary
Diluted magnetic semiconductors(DMS) have long been of great interest in combining the optical character of semiconductor and the magnetism character of ferromagnetic material1–4. (Ga,Mn)As is considered as one of the most promising DMS for spintronic devices due to the compatible growth techniques and relatively high Curie temperature[5,6]. As adding a new degree of freedom associated with spin, the optical properties of (Ga,Mn) As possess a circular dichroism Relative phenomena, such as magnetico-optical(MO) effect[7] and photoinduced magnetization[8], have been widely observed. The study on DMS/semiconductor heterostructure has more application value than the study on spontaneous spin polarization of (Ga,Mn)As itself It can be taken as the interface between ferromagnetic material and semiconductor to realize the carriers injection to nonmagnetic semiconductor which has been used to spin-led[15,16]. The obliquely incident circularly polarized light possesses in-plane angle momentum component, which directly interacts with the in plane spontaneous spin polarization of (Ga,Mn)As and avoids the influence of the giant Zeeman splitting induced by an external magnetic field. We infer the SPD-PC contains non-magnetic related signals
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