Spin Absorption Effect at Ferromagnet/Ge Schottky-Tunnel Contacts

Michihiro Yamada,Kohei Hamaya,Kentarou Sawano,Shinya Yamada,Yuichi Fujita

doi:10.3390/ma11010150

Michihiro Yamada, Kohei Hamaya + Show 3 more

Open Access

https://doi.org/10.3390/ma11010150

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Abstract

We study the influence of the junction size in ferromagnet (FM)/semiconductor (SC) contacts on four-terminal nonlocal spin signals in SC-based lateral spin-valve (LSV) structures. When we use FM/Ge Schottky-tunnel junctions with relatively low resistance-area products, the magnitude of the nonlocal spin signal depends clearly on the junction size, indicating the presence of the spin absorption effect at the spin-injector contact. The temperature-dependent spin signal can also be affected by the spin absorption effect. For SC spintronic applications with a low parasitic resistance, we should consider the influence of the spin absorption on the spin-transport signals in SC-based device structures.

Highlights

Spin-based electronics are expected for one of the beyond CMOS technologies because of the advantages of nonvolatility, reconstructibility, and low power consumption [1,2,3,4,5]
For SC spintronic applications [41] with a low parasitic resistance, we should consider the influence of the spin absorption on the spin-transport signals in SC-based device structures
CoFe/Ge contact in the fabricated lateral spin-valve (LSV) used for spin transport measurements

Summary

Introduction

Spin-based electronics (spintronics) are expected for one of the beyond CMOS technologies because of the advantages of nonvolatility, reconstructibility, and low power consumption [1,2,3,4,5]. Recently reported the spin injection from Py into n-Ge (∼1019 cm−3 ) by using a spin-pumping method through the Ohmic interface with very large contacts (∼105 μm2 ) [27] This means that the spin absorption effect due to the large difference in the spin resistance between Py and Ge is ignored despite the Ohmic junction with a large contact area. To explore the spin absorption effect at the epitaxial FM/Ge Schottky-tunnel interfaces, we study the junction-size dependence of four-terminal nonlocal spin signals in lateral spin valve (LSV) devices with RA ∼ 0.4 kΩ·μm. For SC spintronic applications [41] with a low parasitic resistance, we should consider the influence of the spin absorption on the spin-transport signals in SC-based device structures

Samples and Fabrication Procedures

Results and Discussion

Conclusions