Spin transport and Relaxation in Graphene

By Wei Han, K. McCreary, K. Pi, Wen Wang, Yan Li, H. Wen, Jen-Ru Chen, R. Kawakami. 2010

140 citations recorded by the source corpus.

Abstract We review our recent work on spin injection, transport and relaxation in graphene. The spin injection and transport in single layer graphene (SLG) were investigated using nonlocal magnetoresistance (MR) measurements. Spin injection was performed using either transparent contacts (Co/SLG) or tunneling contacts (Co/MgO/SLG). With tunneling contacts, the nonlocal MR was increased by a factor of ∼1000 and the spin injection/detection efficiency was greatly enhanced from ∼1% (transparent contacts) to ∼30%. Spin relaxation was investigated on graphene spin valves using nonlocal Hanle measurements. For transparent contacts, the spin lifetime was in the range of 50–100 ps. The effects of surface chemical doping showed that for spin lifetimes in the order of 100 ps, charged impurity scattering (Au) was not the dominant mechanism for spin relaxation. While using tunneling contacts to suppress the contact-induced spin relaxation, we observed the spin lifetimes as long as 771 ps at room temperature, 1.2 ns at 4 K in SLG, and 6.2 ns at 20 K in bilayer graphene (BLG). Furthermore, contrasting spin relaxation behaviors were observed in SLG and BLG. We found that Elliot–Yafet spin relaxation dominated in SLG at low temperatures whereas Dyakonov–Perel spin relaxation dominated in BLG at low temperatures. Gate tunable spin transport was studied using the SLG property of gate tunable conductivity and incorporating different types of contacts (transparent and tunneling contacts). Consistent with theoretical predictions, the nonlocal MR was proportional to the SLG conductivity for transparent contacts and varied inversely with the SLG conductivity for tunneling contacts. Finally, bipolar spin transport in SLG was studied and an electron–hole asymmetry was observed for SLG spin valves with transparent contacts, in which nonlocal MR was roughly independent of DC bias current for electrons, but varied significantly with DC bias current for holes. These results are very important for the use of graphene for spin-based logic and information storage applications.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/1a95fb59c3c7bad0d9b3a0744c25efea783621da

How researchers see this paper

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In Atomic and Molecular Physics, and Optics

1. A. Di Bartolomeo
2. Filippo Giubileo
3. Hector Ochoa
4. I. Vera-Marun
5. Ahmet Avsar
6. J. V. Wees
7. B. Özyilmaz
8. Francisco Guinea

In Electrical and Electronic Engineering

1. A. Di Bartolomeo
2. Filippo Giubileo
3. I. Vera-Marun
4. Hector Ochoa
5. Ahmet Avsar
6. J. V. Wees
7. B. Özyilmaz
8. Francisco Guinea

In Materials Chemistry

1. Filippo Giubileo
2. A. Di Bartolomeo
3. Hector Ochoa
4. I. Vera-Marun
5. B. Özyilmaz
6. Francisco Guinea
7. N. M. R. Peres
8. K. Novoselov

Citations in the corpus

• Colloquium : Spintronics in graphene and other two-dimensional materials (2019, background): “…Wolf et al., 2006; Žutić et al., 2004), graphene (Castro Neto et al., 2009; Das Sarma et al., 2011; Peres, 2010), and graphene spintronics (Garcia et al., 2018; Gurram et al., 2018; Han et al., 2012; Pesin and MacDonald, 2012; Roche and Valenzuela, 2014; Seneor et al., 2012; Shiraishi, 2012).”
• The role of contact resistance in graphene field-effect devices (2017, background): “Several attempts to realize graphene based spin-transistor as well as spin valves have been reported [193-200], but the measured values of spin lifetimes always resulted significantly smaller than the prediction.”