Probing Weakly Hybridized Magnetic Molecules by Single-Atom Magnetometry

Abstract

Advances in molecular spintronics rely on the in-depth characterization of the molecular building blocks in terms of their electronic and, more importantly, magnetic properties. For this purpose, inert substrates that interact only weakly with adsorbed molecules are required in order to preserve their electronic states. Here, we investigate the magnetic-field response of a single paramagnetic 5,5'-dibromosalophenatocobalt(II) (CoSal) molecule adsorbed on a weakly interacting magnetic substrate, namely Fe-intercalated graphene (GR/Fe) grown on Ir(111), by using spin-polarized scanning tunneling microscopy and spectroscopy (SP-STM/STS). We have obtained local magnetization curves, spin-dependent tunneling spectra, and spatial maps of magnetic asymmetry for a single CoSal molecule, revealing its magnetic properties and coupling to the local environment. The distinct magnetic behavior of the Co-metal center is found to rely strictly on its position relative to the GR/Fe moiré structure, which determines the level of hybridization between the GR/Fe surface π-system, the molecular ligand π-orbitals and the molecular Co-ion d-orbital.Molecular-based systems are promising candidates for nanospintronic devices, the main examples being single molecular magnets (SMMs) []. In most of these studies the molecules' orbitals were strongly hybridized with the substrates' electronic states [Schwöbel, 2012,

In Situ Synthesis of Metal–Salophene Complexes on Intercalated Graphene

“…The calculated magnetic moments of 4, 2, and 1 μ B for Cr, Fe, and Co, respectively (see Table S4), suggest the preservation of the spin asymmetry of the transition metal atoms’ d states in the MO’s occupancy. Since 5,5′-dibromosalophenato–cobalt­(II) adsorbed on a very similar system, namely Fe-intercalated graphene on Ir(111), preserves the magnetic moment, it is highly probable that this is also true for the synthesized salophene complexes on Gr/Co.…”

“…The investigation and development of alternative approaches for information processing − and storage − using the magnetic moments of electrons and atoms as information carriers has attracted considerable interest in recent years. One interesting branch of those alternatives is molecule-based spintronics. ,− In recent publications, − we presented investigations on 5,5′-dibromosalophenato–cobalt­(II) as a building block for molecular-based spin leads. In combination with the tribromo-triplecobaltsalophene, these can be used for the design of a potential spin logic device via on-surface chemistry.…”

“…In this paper, we report on a successful on-surface metalation of 5,5′-dibromosalophene with Co, Fe, and Cr on Co-intercalated graphene on Ir(111) (Gr/Co) . The graphene layer is known to prevent strong hybridization of molecules with the substrate, ,− while the intercalation, in the valleys of the moiré pattern, provides sufficient interaction with the molecules to limit the desorption of molecules at elevated temperatures. , The successful realization of the metalation reaction was ensured by X-ray photoelectron spectroscopy (XPS) measurements and by comparison of the electronic structure of ex situ and in situ metalated 5,5′-dibromosalophenato–cobalt­(II). Scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations of the obtained products reveal the differences in the electronic structures of different metal–organic complexes.…”

Graphene decoupling through oxygen intercalation on Gr/Co and Gr/Co/Ir interfaces

“…In particular, when grown on noncommensurate surfaces, it forms a moiré pattern and corrugates with a magnitude that depends on the interaction with the metal underneath [2,[5][6][7]. The corrugated Gr sheet can then be used, e.g., as a template for the adsorption of molecules [6,7,[17][18][19][20], as demonstrated e.g. by the deposition of TM-phthalocyanines on Gr/Co/Ir [6,7].…”

Time-dependent spintronic anisotropy in magnetic molecules

“…The transport properties of magnetic molecules have already been extensively studied [20][21][22][23][24][25][26][27][28][29][30][31], including the influence of the Kondo effect [32][33][34][35][36] in the strong coupling regime [37][38][39][40][41][42][43]. However, when the physics of SMM systems incorporates spintronics, new prominent effects are revealed, including switching with spin-polarized currents, Berry-phase blockade or spintronic anisotropy among many others [44][45][46][47][48][49][50][51][52]. In fact, the latter effect is of particular interest, as it allows for generation of magnetic anisotropy in spin-isotropic molecules [53].…”