Mechanically-Controlled Reversible Spin Crossover of Single Fe-Porphyrin Molecules.
basic_science · Level V
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- Record sourced from PubMed, PMID 28498652.
- Also identified by DOI 10.1021/acsnano.7b02567.
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Abstract
Spin-crossover (SCO) molecules are thought to be ideal systems for molecular spintronics when SCO can be precisely controlled at the single-molecule level. This is demonstrated here in the single-molecule junctions of Fe-porphyrin formed in a scanning tunneling microscope. Experimentally, we find that the junctions feature a zero-bias resonance in molecular conductance associated with the Fe spin center. When mechanically stretching or squeezing the junctions by adjusting the tip height, the line shape of the zero-bias resonance varies reversibly. First-principles calculations reveal that widening the junction gap by 2 Å transforms the macrocyclic core hosting the Fe center from a saddle to a planar conformation. This conformational change shortens the Fe-N bonds by 3%, which changes the Fe spin state from S = 2 to S = 1.