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Pré-Publication, Document De Travail Année : 2022

Temperature Dependent Zero-Field Splittings in Graphene

C. Bray
  • Fonction : Auteur
K. Maussang
  • Fonction : Auteur
C. Consejo
  • Fonction : Auteur
J. A. Delgado-Notario
  • Fonction : Auteur
S. S. Krishtopenko
  • Fonction : Auteur
I. Yahniuk
  • Fonction : Auteur
S. Gebert
  • Fonction : Auteur
S. Ruffenach
  • Fonction : Auteur
K. Dinar
  • Fonction : Auteur
E. Moench
  • Fonction : Auteur
K. Indykiewicz
  • Fonction : Auteur
B. Jouault
  • Fonction : Auteur
J. Torres
Y. M. Meziani
  • Fonction : Auteur
W. Knap
  • Fonction : Auteur
A. Yurgens
  • Fonction : Auteur
S. D. Ganichev
  • Fonction : Auteur

Résumé

Graphene is a quantum spin Hall insulator with a 45 $\mu$eV wide non-trivial 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 sub-lattice potential, resulting from the coupling of graphene with its boron nitride substrate, compensates intrinsic spin-orbit coupling and decreases the non-trivial 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 2K-12K by means of sub-Terahertz 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 non-trivial topological gap in graphene.

Dates et versions

hal-03824955 , version 1 (21-10-2022)

Identifiants

Citer

C. Bray, K. Maussang, C. Consejo, J. A. Delgado-Notario, S. S. Krishtopenko, et al.. Temperature Dependent Zero-Field Splittings in Graphene. 2022. ⟨hal-03824955⟩
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