Dynamical Screening of Local Spin Moments at Metal–Molecule Interfaces

Abstract

Transition-metal phthalocyanine molecules have attracted considerable interest in the context of spintronics device development due to their amenability to diverse bonding regimes and their intrinsic magnetism. The latter is highly influenced by the quantum fluctuations that arise at the inevitable metal–molecule interface in a device architecture. In this study, we have systematically investigated the dynamical screening effects in phthalocyanine molecules hosting a series of transition-metal ions (Ti, V, Cr, Mn, Fe, Co, and Ni) in contact with the Cu(111) surface. Using comprehensive density functional theory plus Anderson’s Impurity Model calculations, we show that the orbital-dependent hybridization and electron correlation together result in strong charge and spin fluctuations. While the instantaneous spin moments of the transition-metal ions are near atomic-like, we find that screening gives rise to considerable lowering or even quenching of these. Our results highlight the importance of quantum fluctuations in metal-contacted molecular devices, which may influence the results obtained from theoretical or experimental probes, depending on their possibly material-dependent characteristic sampling time-scales.

Theoretical Insights into the Adsorption of Rare-Earth-Containing Single-Molecule Magnets on Solid Surfaces

“…These surface screening effects can influence the strength of the Coulomb repulsions between d/f electrons in SMMs, potentially resulting in the suppression of high-atomic-like magnetic moments. 58 Considerable discrepancies have been observed between experimentally measured magnetic moments 59 and static local spin density approximation calculations, underscoring the significance of dynamic screening effect, particularly in Hund's metal systems.…”

“…In particular, when a single SMM approaches metal surfaces, notable chemical adsorptions often take place, leading to significant dynamic screening effects on the magnetic states of the center metal ions within SMMs. These surface screening effects can influence the strength of the Coulomb repulsions between d/f electrons in SMMs, potentially resulting in the suppression of high-atomic-like magnetic moments . Considerable discrepancies have been observed between experimentally measured magnetic moments and static local spin density approximation calculations, underscoring the significance of dynamic screening effect, particularly in Hund’s metal systems.…”