Magnetism of 4f-atoms adsorbed on metal and graphene substrates

• Published in: Journal of magnetism and magnetic materials 2019-04, Vol.475, p.211-215
• Main Authors: Shick, A.B., Denisov, A.Yu
• Format: Article
• Language: English
• Subjects: Adatoms; Density functional theory; Dichroism; Dysprosium; Electronic structure; Graphene; Magnetic anisotropy; Magnetic fields; Magnetic induction; Magnetic moments; Magnetism; Quantum tunnelling; Relaxation time; Strong electron correlations; Substrates
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2018.11.078

•Magnetic properties of Dy-adatom on graphene/Ir(111) were investigated.•The combination of the DFT with the Hubbard-I approximation is used.•The Dy adatom magnetic moment of 9.4–9.6 Bohr magnetons is found.•The spin and orbital moments are compared with XMCD.•Insertion of the graphene layer leads to increase of the Dy magnetic relaxation. The electronic structure and magnetism of individual Dy atom adsorbed on the graphene/Ir(111) surface is investigated using the combination of the density functional theory with the Hubbard-I approximation to the Anderson impurity model (DFT + HIA). The divalent Dy2+ adatom is found, with the magnetic moment of 9.4–9.6 μB , depending on the placement of the graphene on the Ir(111) surface, in an external magnetic field. The spin and orbital magnetic moments are evaluated, and compared with the X-ray magnetic circular dichroism (XMCD) data. The positive magnetic anisotropy energy determines the out-of-plane orientation of the Dy adatom magnetic moment. Without an external magnetic field, the ground state is a doublet |J=8,Jz=±7.9〉 , symmetry protected from quantum tunnelling of the magnetization. Calculations show that insertion of the graphene layer promotes reduction of the hybridization between Dy-4f-states and the Ir(111) substrate, and leads to increase of the magnetic moment relaxation time for the Dy adatom.