Ultimate Spin Currents in Commercial Chemical Vapor Deposited Graphene

Abstract

Establishing ultimate spin current efficiency in graphene over industry-standard substrates can facilitate research and development exploration of spin current functions and spin sensing. At the same time, it can resolve core issues in spin relaxation physics while addressing the skepticism of graphene’s practicality for planar spintronic applications. In this work, we reveal an exceptionally long spin communication capability of 45 μm and highest to date spin diffusion length of 13.6 μm in graphene on SiO 2 /Si at room temperature. Employing commercial chemical vapor deposited (CVD) graphene, we show how contact-induced surface charge transfer doping and device doping contributions, as well as spin relaxation, can be quenched in extremely long spin channels and thereby enable unexpectedly long spin diffusion lengths in polycrystalline CVD graphene. Extensive experiments show enhanced spin transport and precession in multiple longest channels (36 and 45 μm) that reveal the highest spin lifetime of ∼2.5–3.5 ns in graphene over SiO 2 /Si, even under ambient conditions. Such performance, made possible due to our devices approaching the intrinsic spin–orbit coupling of ∼20 μeV in graphene, reveals the role of the D’yakonov–Perel’ spin relaxation mechanism in graphene channels as well as contact regions. Our record demonstration, fresh device engineering, and spin relaxation insights unlock the ultimate spin current capabilities of graphene on SiO 2 /Si, while the robust high performance of commercial CVD graphene can proliferate research and development of innovative spin sensors and spin computing circuits.

Ultralow magnetostrictive flexible ferromagnetic nanowires

“…Over the past decade, the field of spintronics has seen rapid progress in the direction of planar multi-terminal spin circuits, made possible due to the advent of graphene and other graphene-like two dimensional (2D) crystals. [51][52][53][54] In metal or graphene planar spin devices, ferromagnetic nanowires are widely employed to generate and detect spin current. The recent flexible spin circuits of graphene 1 opened a new door to utilize the exceptional resilience of 2D materials for flexible 2D spintronics.…”

Van der Waals Multi‐Heterostructures (PN, PIN, and NPN) for Dynamic Rectification in 2D Materials

“…[ 25 ] Metals can also cause surface charge transfer doping, which, along with contact separation can control ultimate device doping, as verified by metal doping effect on graphene. [ 37 ]…”

Gate-Voltage-Modulated Spin Precession in Graphene/WS2 Field-Effect Transistors

“…Graphene has a honeycomb lattice arrangement of carbon atoms, semi-metallic characteristics, and an electronic band structure featuring Dirac cones that impart unique electronic properties [8]. It is considered an excellent candidate for spin transport and spin logic devices due to its high charge carrier density, small hyperfine interactions, and long spin diffusion length [9][10][11][12]. Very small spin-orbit interaction (SOI) is an advantage of graphene for a long spin lifetime, but this makes it difficult to use as a spin channel material for spin FETs.…”