Abstract
Today’s great challenges of energy and informational technologies are addressed with a singular compound, Li- and Na-doped few-layer graphene. All that is impossible for graphite (homogeneous and high-level Na doping) and unstable for single-layer graphene works very well for this structure. The transformation of the Raman G line to a Fano line shape and the emergence of strong, metallic-like electron spin resonance (ESR) modes attest the high level of graphene doping in liquid ammonia for both kinds of alkali atoms. The spin-relaxation time in our materials, deduced from the ESR line width, is 6–8 ns, which is comparable to the longest values found in spin-transport experiments on ultrahigh-mobility graphene flakes. This could qualify our material as a promising candidate in spintronics devices. On the other hand, the successful sodium doping, this being a highly abundant metal, could be an encouraging alternative to lithium batteries.
Highlights
Today’s great challenges of energy and informational technologies are addressed with a singular compound, Liand Na-doped few-layer graphene
Article doping, which is a fingerprint of charge transfer from the alkali atoms toward the carbon, as seen before for graphite intercalation compounds[22,56] and graphene.[23,24,55]
We found that Na dopes exclusively monolayer graphene that is present in the few-layer graphene (FLG) sample
Summary
Today’s great challenges of energy and informational technologies are addressed with a singular compound, Liand Na-doped few-layer graphene. The spin-relaxation time in our materials, deduced from the ESR line width, is 6−8 ns, which is comparable to the longest values found in spintransport experiments on ultrahigh-mobility graphene flakes This could qualify our material as a promising candidate in spintronics devices. Charge state in various forms of carbon can be conveniently controlled using alkali atom doping methods. It led to applications in, for example, energy storage[1] and to the discovery of compelling correlated phases such as superconductivity (with Tc = 11.5 K in CaC62,3 and Tc = 28 K in Rb3C604), spin density waves in fullerides,[5] and the Tomonaga−Luttinger to Fermi liquid crossover in single-wall carbon nanotubes.[6,7]. Doping graphene with light alkali atoms would enable the accurate determination of τs for the itinerant electrons by spin spectroscopy, i.e., electron spin resonance (ESR).[18,19] Light alkali atoms have a small spin−orbit coupling;[20,21] the intrinsic spin lifetime in graphene is expected to be observed with this approach
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