Absence of hyperfine effects in ${}^{13}$C-graphene spin valve devices

Abstract

The carbon isotope ${}^{13}$C, in contrast to ${}^{12}$C, possesses a nuclear magnetic moment and can induce electron spin dephasing in graphene. This effect is usually neglected due to the low abundance of ${}^{13}$C in natural carbon allotropes ($\sim$1 %). Chemical vapor deposition (CVD) allows for artificial synthesis of graphene solely from a ${}^{13}$C precursor, potentially amplifying the influence of the nuclear magnetic moments. In this work we study the effect of hyperfine interactions in pure ${}^{13}$C-graphene on its spin transport properties. Using Hanle precession measurements we determine the spin relaxation time and observe a weak increase of ${\tau }_s$ with doping and a weak change of ${\tau }_s$ with temperature, as in natural graphene. For comparison we study spin transport in pure ${}^{12}$C-graphene, also synthesized by CVD, and observe similar spin relaxation properties. As the signatures of hyperfine effects can be better resolved in oblique spin-valve and Hanle configurations, we use finite-element modeling to emulate oblique signals in the presence of a hyperfine magnetic field for typical graphene properties. Unlike in the case of GaAs, hyperfine interactions with ${}^{13}$C nuclei influence electron spin transport only very weakly, even for a fully polarized nuclear system. Also, in the measurements of the oblique spin-valve and Hanle effects no hyperfine features could be resolved. This work experimentally confirms the weak character of hyperfine interactions and the negligible role of ${}^{13}$C atoms in the spin dephasing processes in graphene.

11 pages, 9 figures

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Cited by in corpus (8)

• Graphene Spintronics
• Particle-hole symmetry protects spin-valley blockade in graphene quantum dots
• Electron spin dynamics of two-dimensional layered materials
• Transition between 1D and 0D spin transport studied by Hanle precession
• Nuclear-induced dephasing and signatures of hyperfine effects in isotopically purified ${}^{13}$C graphene
• High mobility transport in isotopically-enriched ${}^{12}$C and ${}^{13}$C exfoliated graphene
• Electronic and Spin-Orbit Properties of hBN Encapsulated Bilayer Graphene
• Radio-frequency charge detection on graphene electron-hole double quantum dots