Investigation of magnetic properties of $4f$-adatoms on graphene

TL;DR

This study explores the magnetic properties of $4f$-atoms on graphene, revealing significant magnetic anisotropy, spin-orbit effects, and strain-controlled magnetic states, with implications for quantum spin applications.

Contribution

It provides a detailed DFT+$U$ analysis of $4f$-adatoms on graphene, highlighting their magnetic anisotropy, crystal field effects, and strain-dependent magnetic control, which are novel insights.

Findings

Large magnetic anisotropy energies (tens of meVs) due to spin-orbit and crystal field effects.

Strong magneto-elastic coupling in Dy, Ho, Tm adatoms enables strain-based magnetic control.

Quantum tunneling of magnetization suggests potential for protected quantum-spin states.

Abstract

Rare-earth (RE) atoms on top of 2D materials represent an interesting platform with the prospect of tailoring the magnetic anisotropy for practical applications. Here, we investigate the ground state and magnetic properties of selected $4f$-atoms deposited on a graphene substrate in the framework of the DFT+$U$ approach. The inherent strong spin-orbit interaction in conjunction with crystal field effects acting on the localized $4f$-shells results in a substantial magnetic anisotropy energy (tens of meVs), whose angular dependence is dictated by the $C_{6v}$ symmetry of the graphene substrate. We obtain the crystal field parameters and investigate spin-flip events via quantum tunneling of magnetization in the view of achieving a protected quantum-spin behavior. Remarkably, the large spin and orbital moments of the open $4f$-shells (Dy, Ho and Tm) generate a strong magneto-elastic coupling which provides more flexibility to control the magnetic state via the application of external strain.