[NCTS Lecture Series] Graphene intercalated lanthanides: exploring stable 2D magnets from first-principles
Title: [NCTS Lecture Series] Graphene intercalated lanthanides: exploring stable 2D magnets from first-principles
Speaker: Dr. Gustav Bihlmayer (Forschungszentrum Jülich)
Time: 2024/11/29 (Fri.) 11:00-12:00
Place: NCTS Physics Lecture Hall, 4F, Chee-Chun Leung Cosmology Hall, NTU
Abstract
Intercalating lanthanides between graphene and a suitable substrate offers the possibility to realize stable, two-dimensional magnetic systems: large magnetic anisotropies of the 4f atoms or coupling to a magnetic substrate provide the energy barrier to protect the systems from spin fluctuations. In addition, the induced magnetism in the graphene allows studying topological phases with interesting transport properties. In this talk, density functional theory calculations with appropriate extensions of several material combinations will be discussed and comparison to experiments will be shown.Europium can be intercalated between graphene and magnetic surfaces like Co(0001) or Ni(111) forming a √3 × √3 layer [1]. The doping of graphene can create a pronounced flat band at the Fermi level and the interaction of the 4f states with the π band of graphene leads to spin-selective hybridization and opening of the Dirac cone with interesting consequences for edge channels [2]. This system can be compared to Eu on-top of a graphene covered Co substrate, that changes the magnetic coupling between the lanthanide and the substrate [3] and modifies the graphene’s interaction with the 4fstates (see fig. 1). Further stacking combinations are possible and will be discussed [4].
Finally, the magnetism of open-shell 4f atoms on graphene will be investigated and compared to the closed shell counterparts like Eu or Gd [5]. The large magnetic anisotropies observed there will open new possibilities on non-magnetic substrates.
I want to thank my collaborators in these works, M. Jugovac, P. Perna, P. M. Sheverdyaeva, L. Ferrari, J. P. Carbone, J. Bouaziz, N. Atodiresei, and S. Blügel and for funding from the FLAG-ERA grant SOgrapMEM and from CRC 1238 of the Deutsche Forschungs-gemeinschaft.
[1] F. Huttmann et al., Phys. Rev. B 95, 075427 (2017)
[2] P. M. Sheverdyaeva et al., Phys. Rev. Lett. 132, 266401 (2024)
[3] M. Jugovac et al., Adv. Mater. 35, 2301441 (2023)
[4] M. Jugovac et al., Carbon 230, 119666 (2024)
[5] J. P. Carbone et al., Phys. Rev. B 108, 174431 (2023)
