Manipulation of the magnetic state of a porphyrin-based molecule on gold: From Kondo to quantum nanomagnet via the charge fluctuation regime

TL;DR

This study demonstrates reversible control of magnetic states in Fe-Porphyrin molecules on gold surfaces using STM, revealing transitions from magnetic to Kondo regimes driven by charge fluctuations, enabling exploration of quantum magnetic states.

Contribution

It introduces a method to reversibly manipulate and study various magnetic regimes in molecule-surface hybrids, bridging experimental control with theoretical understanding.

Findings

Reversible switching between magnetic states and Kondo regime.

Identification of charge fluctuation-driven transition regimes.

Potential for designing quantum magnetic devices.

Abstract

By moving individual Fe-Porphyrin-based molecules with the tip of Scanning Tunneling Microscope in the vicinity of a Br-atom containing elbow of the herringbone-reconstructed Au(111), we reversibly and continuously control their magnetic state. Several regimes are obtained experimentally and explored theoretically: from the integer spin limit, through intermediate magnetic states with renormalized magnetic anisotropy, until the Kondo-screened regime, corresponding to a progressive increase of charge fluctuations and mixed valency due to an increase in the interaction of the molecular Fe states with the substrate Fermi sea. Our results open a route for the realization, tuning and experimental studies of novel quantum magnetic states in molecule-surface hybrids.