Controlling spins in adsorbed molecules by a chemical switch

Area of Science:

• Materials Science
• Surface Chemistry
• Quantum Mechanics

Background:

• Controllable molecular spins are key for developing advanced magnetic and spintronic materials.
• Switching spin states chemically offers a novel approach to material design.

Purpose of the Study:

• To demonstrate the reversible switching of molecular spins on a ferromagnetic substrate using a chemical stimulus.
• To investigate the mechanism of spin switching in organometallic molecules.

Main Methods:

• Utilizing cobalt(II)tetraphenylporphyrin (CoTPP) ferromagnetically coupled to a nickel thin-film (Ni(001)).
• Employing nitric oxide (NO) as an axial ligand to induce spin state changes.
• Analyzing the formation and dissociation of a NO-CoTPP nitrosyl complex.

Main Results:

• Conclusive evidence of switching molecular spins between magnetic 'off' and 'on' states.
• Nitric oxide addition modifies the Co(2+) coordination sphere, forming a nitrosyl complex ('off' state).
• Thermal dissociation of NO restores the molecular spin to the 'on' state.

Conclusions:

• The study successfully demonstrates NO-induced reversible switching of surface-adsorbed molecular spins.
• The observed phenomenon is attributed to a spin trans effect, offering insights into spin manipulation.
• This work provides a foundation for designing materials with tunable magnetic properties.