Surface Deposition Induced Reduction of the Ground State Spin in Cr10 Wheel

We report the deposition of monolayers and multilayers of {Cr-10(OMe)(20)(O2CCMe3)(10)} wheels, hereafter {Cr-10}, onto Au(111) and Cu(111) single-crystal substrates, and their characterization combining scanning tunneling microscopy, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, X-ray natural linear dichroism, and X-ray magnetic circular dichroism (XMCD). {Cr-10} in bulk shows axial magnetic anisotropy and a cluster total spin S = 9 ground state, stemming from an interaction scheme of two semi-crowns containing four Cr3+ ions interacting ferromagnetically, separated by two Cr3+ antiferromagnetically coupled. The one-monolayer (1ML) samples of {Cr-10} sublimated on Ag(111) and Cu(111) show slightly different applied magnetic field dependence of XMCD signal. The field-dependence of the magnetization evolves from a lower curve for the 1ML {Cr-10} samples to a curve resembling the bulk one as the number of layers is increased, as shown in a 14ML sample. Monte Carlo simulations allow rationalizing the magnetization curves of the 1ML samples in terms of a reduction of the cluster ground-state total spin, S = 3 or S = 6, as a consequence of variations in the intra-wheel coupling interactions induced by the on-surface deposition. The sensitivity of the magnetic configuration of {Cr-10} to minor distortions of the intramolecular conformation might be exploited to control magnetism by external stimuli for applications.

Automated summary

We investigate the deposition of monolayers and multilayers of {Cr-10} wheels on Au(111) and Cu(111) substrates, and analyze their properties using various spectroscopic techniques. The magnetic behavior of {Cr-10} monolayers on Ag(111) and Cu(111) exhibits slight differences compared to the bulk, which can be rationalized by considering the impact of surface deposition on intra-wheel coupling interactions. The sensitivity of {Cr-10} to molecular distortions suggests potential applications for controlling magnetism with external stimuli.