Spin communication over 30 <i>µ</i> m long channels of chemical vapor deposited graphene on SiO ₂

Abstract

We demonstrate a high-yield fabrication of non-local spin valve devices with\nroom-temperature spin lifetimes of up to 3 ns and spin relaxation lengths as\nlong as 9 $\\mu$m in platinum-based chemical vapor deposition (Pt-CVD)\nsynthesized single-layer graphene on SiO$_2$/Si substrates. The spin-lifetime\nsystematically presents a marked minimum at the charge neutrality point, as\ntypically observed in pristine exfoliated graphene. However, by studying the\ncarrier density dependence beyond n ~ 5 x 10$^{12}$ cm$^{-2}$, via\nelectrostatic gating, it is found that the spin lifetime reaches a maximum and\nthen starts decreasing, a behavior that is reminiscent of that predicted when\nthe spin-relaxation is driven by spin-orbit interaction. The spin lifetimes and\nrelaxation lengths compare well with state-of-the-art results using exfoliated\ngraphene on SiO$_2$/Si, being a factor two-to-three larger than the best values\nreported at room temperature using the same substrate. As a result, the spin\nsignal can be readily measured across 30 $\\mu$m long graphene channels. These\nobservations indicate that Pt-CVD graphene is a promising material for\nlarge-scale spin-based logic-in-memory applications.\n