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Spin Excitations in a 4f-3d Heterodimer on MgO
A Singha1,2,3, F Donati1,2,3, F D Natterer2,4
1Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea.
Physical Review Letters
|January 5, 2019
Summary
We studied holmium-cobalt (HoCo) dimers, the smallest lanthanide-transition metal compounds. We observed magnetic excitations and found ferromagnetic coupling, differing from bulk materials.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Surface Science
Background:
- Lanthanide-transition metal intermetallic compounds are crucial in magnetism.
- Understanding small-scale magnetic systems is key to developing novel magnetic materials.
- The magnetic properties of single dimers remain largely unexplored.
Purpose of the Study:
- To investigate the magnetic properties of holmium-cobalt (HoCo) dimers.
- To model the smallest intermetallic compound of a lanthanide and a transition metal.
- To determine the exchange interaction and magnetic level distribution in HoCo dimers.
Main Methods:
- Adsorption of HoCo dimers on ultrathin magnesium oxide (MgO) films on silver (Ag).
- Inelastic electron tunneling spectroscopy (IETS) to detect magnetic excitations.
- Application of an external magnetic field to confirm magnetic origin of excitations.
- Density functional theory (DFT) and spin Hamiltonian analysis for theoretical modeling.
Main Results:
- Detection of inelastic excitations in HoCo dimers using scanning tunneling spectroscopy (STS).
- Confirmation of the magnetic origin of these excitations via external magnetic field application.
- Determination of the magnetic level distribution and exchange interaction sign and magnitude.
- Observation of ferromagnetic coupling between holmium and cobalt atoms in the dimer.
Conclusions:
- HoCo dimers serve as a model system for studying magnetism in the smallest lanthanide-transition metal intermetallic compounds.
- The study demonstrates the capability of STS to probe magnetic excitations in single 4f-element-containing dimers.
- Ferromagnetic coupling in HoCo dimers contrasts with typical antiferromagnetic coupling found in bulk 4f-3d compounds, highlighting unique nanoscale magnetic behavior.
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