Direct observation of a highly spin-polarized organic spinterface at room temperature

Organic semiconductors constitute promising candidates toward large-scale electronic circuits that are entirely spintronics-driven. Toward this goal, tunneling magnetoresistance values above 300% at low temperature suggested the presence of highly spin-polarized device interfaces. However, such spinterfaces have not been observed directly, let alone at room temperature. Thanks to experiments and theory on the model spinterface between phthalocyanine molecules and a Co single crystal surface, we clearly evidence a highly efficient spinterface. Spin-polarised direct and inverse photoemission experiments reveal a high degree of spin polarisation at room temperature at this interface. We measured a magnetic moment on the molecule’s nitrogen p orbitals, which substantiates an ab-initio theoretical description of highly spin-polarised charge conduction across the interface due to differing spinterface formation mechanisms in each spin channel. We propose, through this example, a recipe to engineer simple organic-inorganic interfaces with remarkable spintronic properties that can endure well above room temperature

Structural, elastic, thermodynamic, electronic, and optical properties of

The present paper aims to investigate the structural, elastic, thermodynamic, electronic, and optical properties of $$\hbox {CaMg}_{2}\hbox {AN}_{3}$$($$\hbox {A}= \hbox {Al}$$ and Ga) using first-principle calculations and quasi-harmonic Debye model. The obtained ground-state lattice parameters were in good agreement with the experimental values. Pressure effect on the structural parameters was tested up to 20 GPa, the results reveal that the contractions are higher along the c-axis than along the a-axis. The computed single-crystal elastic moduli show that the unidirectional constant $$\hbox {C}_{11}$$ is about 60% greater than $$\hbox {C}_{33}$$. Cauchy pressure and Poisson ratio suggest that the chemical bonding in $$\hbox {CaMg}_{2}\hbox {AN}_{3}$$ is a mixture of covalent and ionic characters. Elastic anisotropy was discussed using different approaches, and the results show a weak elastic anisotropy. By means of Gibbs program, we have evaluated the thermodynamic properties such as Debye temperature \uptheta _{{D}}, heat capacities $${C}_{{v}}$$ and $${C}_{{p}}$$, and expansion thermal coefficient under pressure ranging from 0 to 20 GPa and at temperature ranging from 0 to 1500 K for both compounds. The evaluated value of Dulong–Petit limit of both the semiconductors is $$360.5\ \hbox {Jmol}^{-1}\hbox {K}^{-1}$$. Band structure curves show a direct band gap of about 1.88 and 0.78 eV for $$\hbox {CaMg}_{2}\hbox {AlN}_{3}$$ and $$\hbox {CaMg}_{2} \hbox {GaN}_{3}$$, respectively. Density of states and charge densities analysis confirm the predicted ionic-covalent bonding in both nitrides. Additionally, optical functions such as the refractive index, the reflectivity, and the absorption coefficient were calculated and discussed for two polarized radiations

Highly spin-polarized carbon-based spinterfaces

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Chemisorption of manganese phthalocyanine on Cu(001) surface promoted by van der Waals interactions

International audiencevan der Waals (vdW) interactions within density functional theory are shown to strongly reduce the distance between manganese phthalocyanine (MnPc) and a Cu(001) surface to that found by x-ray standing wave experiments. Thus, the physisorbed ground state that is predicted within the generalized-gradient approximation formalism is replaced by a chemisorbed ground state once vdW interactions are taken into account. These findings indicate how to systematically obtain the correct theoretical adsorption distance for complex molecules and thus accurately predict the properties of the ensuing molecule/metal interface. The reduction of the experimental work function upon molecular adsorption is satisfactorily accounted for and explained in terms of Friedel-like oscillations of the charge density at the vicinity of the MnPc molecule that change the sign of the charge transfer electric dipole. This shows how vdW interactions can strongly impact charge injection in organic electronic devices

Breakdown of the electron-spin motion upon reflection at metal-organic or metal-carbon interfaces

Spin-polarized electron scattering experiments on different metal-organic and metal-carbon interfaces are performed. A completely unexpected behavior of the spin-motion angles as well as of related quantities as a function of the organic layer or carbon coverage is observed. In fact, by deposition of organic molecules or carbon onto ferromagnetic as well as nonmagnetic metal surfaces in the submonolayer thickness range, the electron reflection amplitude, i.e., both the reflectivity and the reflection phase, become spin independent. Our findings show that this behavior is a very general phenomenon which is independent of the electron energy and the choice of the metal as well as of the organic molecules and thus does not depend on the choice of the specific interface

Loss of H3K9 tri-methylation alters chromosome compaction and transcription factor retention during mitosis

Recent studies have shown that repressive chromatin machinery, including DNA methyltransferases (DNMTs) and Polycomb Repressor Complexes (PRCs), bind to chromosomes throughout mitosis and their depletion results in increased chromosome size. Here we show that enzymes that catalyse H3K9 methylation, such as Suv39h1, Suv39h2, G9a and Glp, are also retained on mitotic chromosomes. Surprisingly however, mutants lacking H3K9me3 have unusually small and compact mitotic chromosomes that are associated with increased H3S10ph and H3K27me3 levels. Chromosome size and centromere compaction in these mutants were rescued by providing exogenous Suv39h1, or inhibiting Ezh2 activity. Quantitative proteomic comparisons of native mitotic chromosomes isolated from wildtype versus Suv39h1/Suv39h2 double-null ESCs revealed that H3K9me3 was essential for the efficient retention of bookmarking factors such as Esrrb. These results highlight an unexpected role for repressive heterochromatin domains in preserving transcription factor binding through mitosis, and underscore the importance of H3K9me3 for sustaining chromosome architecture and epigenetic memory during cell division

Chemisorption of manganese phthalocyanine on Cu(001) surface promoted by van der Waals interactions

van der Waals (vdW) interactions within density functional theory are shown to strongly reduce the distance between manganese phthalocyanine (MnPc) and a Cu(001) surface to that found by x-ray standing wave experiments. Thus, the physisorbed ground state that is predicted within the generalized-gradient approximation formalism is replaced by a chemisorbed ground state once vdW interactions are taken into account. These findings indicate how to systematically obtain the correct theoretical adsorption distance for complex molecules and thus accurately predict the properties of the ensuing molecule/metal interface. The reduction of the experimental work function upon molecular adsorption is satisfactorily accounted for and explained in terms of Friedel-like oscillations of the charge density at the vicinity of the MnPc molecule that change the sign of the charge transfer electric dipole. This shows how vdW interactions can strongly impact charge injection in organic electronic devices. DOI: 10.1103/PhysRevB.87.15541