Anisotropic Hyperfine Interaction of Surface-Adsorbed Single Atoms

Area of Science:

• Surface Science
• Quantum Chemistry
• Materials Science

Background:

• Hyperfine interactions are crucial probes of local chemical environments in diverse scientific fields.
• Conventional methods average hyperfine data over many spins, obscuring single-atom details.
• Understanding single-atom hyperfine interactions is key to advanced materials design.

Purpose of the Study:

• To measure hyperfine spectra at the single-atom level using scanning tunneling microscopy (STM) and electron spin resonance (ESR).
• To determine the full hyperfine tensors, including isotropic and anisotropic components, for specific isotopes.
• To investigate the origins of hyperfine anisotropy using theoretical calculations.

Main Methods:

• Utilizing a scanning tunneling microscope (STM) coupled with electron spin resonance (ESR) spectroscopy.
• Performing vector-field ESR spectroscopy and STM-based atom manipulation.
• Conducting density functional theory (DFT) calculations to model electronic structures.

Main Results:

• Achieved single-atom resolution for hyperfine interaction measurements of hydrogenated-Ti on MgO/Ag(100).
• Determined the complete hyperfine tensors for 47Ti and 49Ti isotopes.
• Identified significant spatial anisotropy in hyperfine interactions, linked to electron spin density distribution.

Conclusions:

• ESR-STM spectroscopy enables precise, single-atom characterization of hyperfine interactions.
• The study reveals insights into electronic ground states and atomic-scale chemical environments.
• Demonstrates the potential of this technique for advanced materials characterization.