Controlling orbital-selective Kondo effects in a single molecule through coordination chemistry

Area of Science:

• Quantum Chemistry
• Surface Science
• Molecular Magnetism

Background:

• Iron(II) phthalocyanine (FePc) on Au(111) displays Kondo effects due to its multi-spin and multi-orbital electronic structure.
• Two unpaired electrons in d(z)(2) and dπ orbitals lead to stepwise spin and spin+orbital Kondo effects.

Purpose of the Study:

• Investigate the impact of CO and NO coordination on FePc Kondo effects.
• Explore the use of single-molecule chemistry to control quantum states.

Main Methods:

• Scanning tunneling microscopy (STM) for probing electronic properties.
• Density functional theory (DFT) calculations for theoretical analysis.

Main Results:

• CO coordination quenches Kondo effects by inducing a singlet spin state.
• NO coordination results in a surviving spin Kondo effect due to specific orbital interactions.
• Pulsed voltage reversibly detaches diatomic molecules.

Conclusions:

• FePc on Au(111) exhibits controllable Kondo effects modulated by chemical stimuli.
• Single-molecule chemistry offers a pathway for reversible control of spin and quantum states.