Gate-tunable black phosphorus spin valve with nanosecond spin lifetimes

• Published in: Nature physics Vol. 13; no. 9; pp. 888 - 893
• Main Authors: Avsar, Ahmet, Tan, Jun Y., Kurpas, Marcin, Gmitra, Martin, Watanabe, Kenji, Taniguchi, Takashi, Fabian, Jaroslav, Özyilmaz, Barbaros
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-09-2017; Nature Publishing Group
• Subjects: 140/133; 639/766/1130/2798; 639/766/119/1001; 639/925/927/1062; Atomic; Carrier density; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Current carriers; Diodes; Electric charge; Electron mobility; Electron spin; Mathematical and Computational Physics; Molecular; Optical and Plasma Physics; Phosphorus; Physics; Precession; Semiconductor devices; Spin valves; Spinning; Theoretical; Transistors; Transport
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/nphys4141

Two-dimensional materials offer new opportunities for both fundamental science and technological applications, by exploiting the electron’s spin. Although graphene is very promising for spin communication due to its extraordinary electron mobility, the lack of a bandgap restricts its prospects for semiconducting spin devices such as spin diodes and bipolar spin transistors. The recent emergence of two-dimensional semiconductors could help overcome this basic challenge. In this letter we report an important step towards making two-dimensional semiconductor spin devices. We have fabricated a spin valve based on ultrathin (∼5 nm) semiconducting black phosphorus (bP), and established fundamental spin properties of this spin channel material, which supports all electrical spin injection, transport, precession and detection up to room temperature. In the non-local spin valve geometry we measure Hanle spin precession and observe spin relaxation times as high as 4 ns, with spin relaxation lengths exceeding 6 μm. Our experimental results are in a very good agreement with first-principles calculations and demonstrate that the Elliott–Yafet spin relaxation mechanism is dominant. We also show that spin transport in ultrathin bP depends strongly on the charge carrier concentration, and can be manipulated by the electric field effect.
The injection, transport and manipulation of spins using electric fields in ultrathin films of black phosphorus show the potential of this material as a platform for two-dimensional semiconductor spintronics devices.