TY - JOUR
T1 - Topological valley currents via ballistic edge modes in graphene superlattices near the primary Dirac point
AU - Li, Yang
AU - Amado, Mario
AU - Hyart, Timo
AU - Mazur, Grzegorz P.
AU - Robinson, Jason W.A.
PY - 2020/12/4
Y1 - 2020/12/4
N2 - Graphene on hexagonal boron nitride (hBN) can exhibit a topological phase via mutual crystallographic alignment. Recent measurements of nonlocal resistance (Rnl) near the secondary Dirac point (SDP) in ballistic graphene/hBN superlattices have been interpreted as arising due to the quantum valley Hall state. We report hBN/graphene/hBN superlattices in which Rnl at SDP is negligible, but below 60 K approaches the value of h/2e2 in zero magnetic field at the primary Dirac point with a characteristic decay length of 2 μm. Furthermore, nonlocal transport transmission probabilities based on the Landauer-Büttiker formalism show evidence for spin-degenerate ballistic valley-helical edge modes, which are key for the development of valleytronics.
AB - Graphene on hexagonal boron nitride (hBN) can exhibit a topological phase via mutual crystallographic alignment. Recent measurements of nonlocal resistance (Rnl) near the secondary Dirac point (SDP) in ballistic graphene/hBN superlattices have been interpreted as arising due to the quantum valley Hall state. We report hBN/graphene/hBN superlattices in which Rnl at SDP is negligible, but below 60 K approaches the value of h/2e2 in zero magnetic field at the primary Dirac point with a characteristic decay length of 2 μm. Furthermore, nonlocal transport transmission probabilities based on the Landauer-Büttiker formalism show evidence for spin-degenerate ballistic valley-helical edge modes, which are key for the development of valleytronics.
UR - http://www.scopus.com/inward/record.url?scp=85097099463&partnerID=8YFLogxK
U2 - 10.1038/s42005-020-00495-y
DO - 10.1038/s42005-020-00495-y
M3 - Article
AN - SCOPUS:85097099463
SN - 2399-3650
VL - 3
JO - Communications Physics
JF - Communications Physics
IS - 1
M1 - 224
ER -