Interface-Induced Spin and Dipole Ordering of the Copper Spin 1/2 Molecule: Bis(4-cyano-2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II)

Abstract

Using light-polarization-dependent angle-resolved photoemission, the metal-organic molecule bis(4-cyano-2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II) (or Cu(CNdpm) 2 , i.e., C 24 H 36 N 2 O 4 Cu, Cu(II)) is observed to adopt a preferential orientation that depends on the film thickness and substrate when adsorbed on Co(111) and Cu(111). In addition, the final-state binding energies change with film thickness, suggesting the substrates affect the screening or charging in the photoemission final state. For Cu(CNdpm) 2 deposited on Co(111), the induced spin polarization was found to depend strongly on the molecular orbital contributions.

Radiation-induced decomposition of the metal-organic molecule Bis(4-cyano-2,2,6,6-tetramethyl-3,5-heptanedionato)copper(II)

“…As described in [15], the spectrum taken at a photon energy of 49 eV (Fig. 1b) tends to emphasize the ligand contributions, while that in Fig.…”

“…Irradiation and photo-degradation of adsorbed Cu(CNdpm) 2 on Co (1 1 1) Cu(CNdpm) 2 is close to being a copper spin 1/2 system [19] and adsorbs molecularly with a strong preferential molecular orientation [15]. As demonstrated in previous work [15,19], Cu(CNdpm) 2 adsorbed onto the surface of Co (1 1 1) provides photoemission spectra very similar to adsorption on Cu(1 1 1), in spite of expected differences in substrate reactivity. For the thicker molecular films (50 molecular layers), the photoemission spectra taken at higher photon energies of 79 eV (Fig.…”

“…The epitaxial Co(1 1 1) substrate films were grown prior to each experiment on Cu(1 1 1) single crystals, to a cobalt thickness of 20 Å or about 7 monolayers (ML), as described in prior work [15,16]. The clean Cu(1 1 1) surfaces were prepared by repeated cycles of Ar + ion sputtering and annealing of a Cu single crystal, prior to Co deposition.…”

“…Ultraviolet photoemission spectra (ARPES) of the adsorbed molecular layers on Co(1 1 1) were acquired at the U5UA undulator spherical grating monochromator (SGM) beamline at the National Synchrotron Light Source (NSLS) [17,18], as described elsewhere [15]. The ultrahigh vacuum photoemission end-station at the SGM beamline was equipped with a hemispherical electron energy analyzer (EA125, Omicron GmbH) [17,18].…”

Recent progress in organic spintronics

“…This has been studied in some detail for various π-conjugated molecules adsorbed on ferromagnetic surfaces. The most common experimental techniques to probe the interface electronic and magnetic structure are x-ray magnetic circular dichroism (XMCD) [93][94][95], spin-polarized scanning tunneling microscopy (SP-STM) [90,[96][97][98], spin-polarized metastable de-excitation spectroscopy(SP-MDS) [99][100][101], spin-polarized ultraviolet photoelectron spectroscopy (SP_UPS) [102][103][104], and spin-resolved two-photon photoemission (SR-2PPE) [77]. Modeling is typically done with density functional theory (DFT) [89,95,97,98,[104][105][106][107][108][109].…”