Anomalous electron-electron interactions in epitaxial graphene on SiC

Disorder-controlled linear magnetoresistance in monolayer graphene

“…The two samples used in this study are quasi-freestanding monolayer graphene grown on the Si-face (0001) of silicon carbide (SiC) substrate at 1923 K and then annealed at 1173 K under hydrogen atmosphere. The Raman spectra have proved that both samples are monolayer graphene (see supplementary materials in a previous paper [21]). After growth, the samples were bonded with silver wires by silver paint, and magneto-transport measurements were performed with a perpendicular B in a physical property measurement system (Quantum Design).…”

“…Both our samples are ptype, for which there are two possible reasons: one is the presence of the silicates at the graphene/SiC interface [22] and the other is the absorption of some acceptors like H 2 O and/or O 2 molecules from ambient environment [23,24]. Since the hole concentration p can be continuously reduced by annealing [21], the latter must play a dominant role in p-type conduction for our samples. One sample, which is referred to as sample S1, has a p of 1.9 × 10 13 cm −2 and the other sample, named after sample S2, has the higher p of 2.5 × 10 13 cm −2 at room temperature.…”

“…First, for a fixed t, the f exhibits an increase with increasing T . This can be attributed to the increase in p with T due to thermal activation [21], which leads to a smaller l and thus a larger f at higher T . We note that the increase in p with T is not very large in the studied T range (e.g., p = 1.6 × 10 13 cm −2 at 2 K and p = 1.9 × 10 13 cm −2 at 300 K for sample S1 with t = 0 s).…”