%0 Journal Article
%T Temperature-dependent zero-field splittings in graphene
%+ Laboratoire Charles Coulomb (L2C)
%+ Institut d’Electronique et des Systèmes (IES)
%+ Universidad de Salamanca
%+ Universität Regensburg (UR)
%+ Institute of High Pressure Physics [Warsaw] (IHPP)
%+ Wroclaw University of Science and Technology
%+ Modélisation et Spectroscopie THz (MOST)
%+ Matériaux (MAT)
%+ Capteurs et Instrumentations (CI)
%+ Chalmers University of Technology [Göteborg]
%A Bray, C.
%A Maussang, K.
%A Consejo, C.
%A Delgado-Notario, J.
%A Krishtopenko, S.
%A Yahniuk, I.
%A Gebert, S.
%A Ruffenach, S.
%A Dinar, K.
%A Moench, E.
%A Eroms, J.
%A Indykiewicz, K.
%A Jouault, B.
%A Torres, J.
%A Meziani, Y.
%A Knap, W.
%A Yurgens, A.
%A Ganichev, S.
%A Teppe, F.
%< avec comité de lecture
%@ 2469-9950
%J Physical Review B
%I American Physical Society
%V 106
%N 24
%P 245141
%8 2022
%D 2022
%R 10.1103/PhysRevB.106.245141
%Z Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]Journal articles
%X Graphene is a quantum spin Hall insulator with a 45 µeV 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.
%G English
%2 https://hal.science/hal-03925414/document
%2 https://hal.science/hal-03925414/file/2209.14001.pdf
%L hal-03925414
%U https://hal.science/hal-03925414
%~ CNRS
%~ IES
%~ L2C
%~ UNIV-MONTPELLIER
%~ ANR
%~ UM-2015-2021
%~ UM-EPE
%~ TEST3-HALCNRS