Femtosecond laser-induced spin dynamics in single-layer graphene/CoFeB thin films.

Graphene/ferromagnet hybrid heterostructures are important building blocks of spintronics due to the unique ability of graphene to transport spin current over unprecedented distances and possible increase in its spin-orbit coupling due to proximity and hybridization. Here, we present magnetization dynamics over a femtosecond to nanosecond timescale by employing an all-optical time-resolved magneto-optical Kerr effect technique in single-layer graphene (SLG)/CoFeB thin films with varying CoFeB thickness and compared them with reference CoFeB thin films without an SLG underlayer. Gilbert damping variation with CoFeB thickness is modelled to extract spin-mixing conductance for the SLG/CoFeB interface and isolate the two-magnon scattering contribution from spin pumping.

Interfacial Interaction of Absorbate Copper Phthalocyanine with PVDF Based Ferroelectric Polymer Substrates: A Spectroscopic Study.

Studies of CuPc thin films on underlying ferroelectric copolymeric and terpolymeric substrates have been performed by ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Work function (WF) and highest occupied molecular orbital (HOMO) energy level shift observed from UPS spectroscopy for successive deposition of CuPc molecules on ferroelectric polymer surfaces confirm the formation of interface dipole at the CuPc-ferroelectric polymer interface owing to charge transfer from the tailing region of the CuPc HOMO density of states (DOS) to the ferroelectric polymer layer. According to our thickness dependent XPS data, CuPc molecules are coupled to the organic ferroelectric surfaces through the central metal atom of the CuPc molecules, i.

Electronic structure of twisted and planar rubrene molecules: a density functional study.

X-ray absorption spectra (XAS), the density of states (DOS) and the electron density distribution of the HOMO and LUMO for flat and twisted rubrene molecules have been calculated using density functional theory (DFT). The simulated XAS spectra are validated by experimental C K-edge near-edge X-ray absorption fine structure (NEXAFS) data. We demonstrate that the NEXAFS spectra of rubrene thin films of different thicknesses can be explained in terms of different combinations of spectral intensity from the twisted and the flat randomly oriented molecules.

Oxidation of rubrene thin films: an electronic structure study.

The performances of organic semiconductor devices are crucially linked with their stability at the ambient atmosphere. The evolution of electronic structures of 20 nm thick rubrene films exposed to ambient environment with time has been studied by UV and X-ray photoemission spectroscopy (UPS and XPS), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and density functional theory (DFT). XPS, NEXAFS data, and DFT calculated values suggest the formation of rubrene-epoxide and rubrene-endoperoxide through reaction of tetracene backbone with oxygen of ambient environment.

Crystalline growth of rubrene film enhanced by vertical ordering in cadmium arachidate multilayer substrate.

The growth of highly crystalline rubrene thin films for organic field effect transistor (OFET) application remains a challenge. Here, we report on the vapor-deposited growth of rubrene films on the substrates made of cadmium arachidate (CdA) multilayers deposited onto SiO2/Si(100) via the Langmuir-Blodgett technique. The CdA films, containing 2n+1 layers, with integer n ranging from 0 to 4, are surface-terminated identically by the methyl group but exhibit the thickness-dependent morphology.