Valence Orbitals Driving the Spin Dynamics in a Rare-Earth Single-Atom Magnet.

Area of Science:

• Condensed Matter Physics
• Surface Science
• Quantum Magnetism

Background:

• Single atom magnets (SAMs) are promising for high-density data storage.
• Understanding spin dynamics is crucial for SAM device applications.
• Dysprosium (Dy) on graphene/Ir(111) serves as a model system for studying SAM behavior.

Purpose of the Study:

• To investigate the spin dynamics of single Dy atoms on graphene/Ir(111).
• To identify the key factors governing magnetization relaxation and reversal.
• To clarify the role of different electronic shells and angular momenta in spin behavior.

Main Methods:

• Spin-polarized scanning tunneling microscopy (SP-STM) for reading and writing magnetic states.
• Quantum master equation analysis to model spin dynamics.
• In-situ experimental techniques to probe electronic and magnetic properties.

Main Results:

• Identified strongly spin-polarized 5d6s valence shells influencing spin dynamics.
• Demonstrated intra-atomic exchange coupling between 5d6s and 4f shells is critical.
• Established atomic total angular momentum (J_{z}^{tot}) as the determining quantum number for stability and reversal, not solely the 4f shell's (J_{z}^{4f}).

Conclusions:

• The spin dynamics of Dy SAMs are governed by a combination of valence shell polarization and 4f shell coupling.
• Atomic total angular momentum provides a more accurate description of SAM stability and reversal mechanisms.
• This work offers insights into designing and controlling single-atom magnetic systems.