Temperature-dependent zero-field splittings in graphene
Journal article, 2022
Graphene is a quantum spin Hall insulator with a 45μeV-wide nontrivial topological gap induced by the intrinsic spin-orbit coupling. Even though this zero-field spin splitting is weak, it makes graphene an attractive candidate for applications in quantum technologies, given the resulting long spin-relaxation time. On the other side, the staggered sublattice potential, resulting from the coupling of graphene with its boron nitride substrate, compensates intrinsic spin-orbit coupling and decreases the nontrivial topological gap, which may lead to the phase transition into trivial band insulator state. In this work, we present extensive experimental studies of the zero-field splittings in monolayer and bilayer graphene in a temperature range 2-12 K by means of subterahertz photoconductivity-based electron spin-resonance technique. Surprisingly, we observe a decrease of the spin splittings with increasing temperature. We discuss the origin of this phenomenon by considering possible physical mechanisms likely to induce a temperature dependence of the spin-orbit coupling. These include the difference in the expansion coefficients between the graphene and the boron nitride substrate or the metal contacts, the electron-phonon interactions, and the presence of a magnetic order at low temperature. Our experimental observation expands knowledge about the nontrivial topological gap in graphene.
Author
C. Bray
Laboratoire Charles Coulomb
K. Maussang
IES Institut d'Electronique et des Systèmes
C. Consejo
Laboratoire Charles Coulomb
J. A. Delgado-Notario
University of Salamanca
Polish Academy of Sciences
S. Krishtopenko
Laboratoire Charles Coulomb
I. Yahniuk
Polish Academy of Sciences
University of Regensburg
S. Gebert
IES Institut d'Electronique et des Systèmes
Laboratoire Charles Coulomb
S. Ruffenach
Laboratoire Charles Coulomb
K. Dinar
Laboratoire Charles Coulomb
E. Moench
University of Regensburg
J. Eroms
University of Regensburg
Kornelia Indykiewicz
Wrocław University of Science and Technology
B. Jouault
Laboratoire Charles Coulomb
J. Torres
IES Institut d'Electronique et des Systèmes
Y. M. Meziani
University of Salamanca
W. Knap
Polish Academy of Sciences
Avgust Yurgens
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
S.D. Ganichev
Polish Academy of Sciences
University of Regensburg
F. Teppe
Laboratoire Charles Coulomb
Polish Academy of Sciences
Physical Review B
24699950 (ISSN) 24699969 (eISSN)
Vol. 106 24 245141Subject Categories
Other Physics Topics
Theoretical Chemistry
Condensed Matter Physics
DOI
10.1103/PhysRevB.106.245141
Related datasets
Temperature-dependent zero-field splittings in graphene [dataset]
DOI: 10.57745/ihwwbf