Efficient Ab Initio Multiplet Calculations for Magnetic Adatoms on MgO

Area of Science:

• Surface Science
• Condensed Matter Physics
• Quantum Chemistry

Background:

• Direct observation of electron dynamics at the atomic limit is possible via scanning probe microscopy and single-atom electron spin resonance.
• Interpreting experimental data relies heavily on model Hamiltonians, but fitting these limits exploration of potential systems.

Purpose of the Study:

• To develop a computational method for predicting fundamental magnetic properties of adatoms on surfaces.
• To overcome limitations of fitting effective spin Hamiltonians to experimental data.
• To enable exploration of a vast number of potential magnetic systems.

Main Methods:

• Utilized plane-wave density functional theory (DFT) as a starting point.
• Constructed a multiplet Hamiltonian using maximally localized Wannier functions.
• Incorporated spin-orbit and electron-electron interactions into the Hamiltonian.
• Solved the reduced Hamiltonian via exact diagonalization.

Main Results:

• Accurately predicted spin orientation and anisotropy for prototypical 3d transition metals (Mn, Fe, Co) on MgO.
• Demonstrated strong agreement between computational predictions and experimental data.
• Validated the method's capability without relying on experimental input.

Conclusions:

• The developed method accurately predicts magnetic properties of adatoms on surfaces.
• This approach facilitates the exploration and prediction of fundamental magnetic properties for novel materials.
• Offers a powerful, input-independent tool for advancing nanoscale magnetism research.