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Tuning a Two-Impurity Kondo System by a Moiré Superstructure.
Sergey Trishin1, Christian Lotze1, Friedemann Lohss1
1Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany.
Physical Review Letters
|May 12, 2023
Summary
Researchers studied magnetic interactions of manganese (Mn) atoms on a molybdenum disulfide (MoS2) surface. They found that the distance between atoms and their position on the surface significantly influence magnetic properties and electron interactions.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Chemistry
Background:
- Two-impurity Kondo models are fundamental for understanding correlated spin-fermion systems.
- Manganese (Mn) atoms on surfaces provide a platform to study localized magnetic moments and their interactions.
- Molybdenum disulfide (MoS2) offers a unique two-dimensional material platform with a moiré structure that can influence adatom properties.
Purpose of the Study:
- To investigate the tunability of magnetic exchange interactions in Mn adatoms on MoS2/Au(111).
- To explore the influence of adatom distance and substrate moiré structure on Kondo physics and magnetic coupling.
- To understand the electronic properties and ground states of isolated Mn adatoms and dimers.
Main Methods:
- Fabrication of Mn adatoms and dimers on a MoS2 monolayer on Au(111).
- Differential conductance measurements using scanning tunneling microscopy (STM) to probe Kondo resonances and electronic states.
- Theoretical interpretation relating experimental observations to adatom spin interactions with substrate conduction electrons.
Main Results:
- Kondo peak heights for isolated Mn adatoms varied with their position on the MoS2 moiré structure.
- Mn dimers exhibited split Kondo resonances at larger separations and an antiferromagnetic coupling leading to a molecular-singlet ground state at closer distances.
- The singlet-triplet splitting in dimers showed strong sensitivity to the moiré structure, correlating with single-atom Kondo peak heights.
Conclusions:
- The study demonstrates precise control over magnetic interactions of Mn adatoms on MoS2 via adatom positioning and spacing.
- Evidence suggests coupling of the adatom spin to multiple conduction electron channels, influenced by the substrate's moiré potential.
- Results provide insights into the fundamental physics of correlated spin-fermion systems in engineered 2D material environments.
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