43 research outputs found
In-Depth NMR Investigation of the Magnetic Hardening in Co Thin Films Induced by the Interface with Molecular Layers
The hybridization of the surface orbitals of thin ferromagnetic layers with molecular orbitals represents a soft but efficient technology that is able to induce in ferromagnetic component radical modifications of the key magnetic parameters, such as magnetization, magnetic anisotropy, and others. These effects are investigated in 7 nm thick polycrystalline Co films interfaced with C-60 and Gaq(3) molecular layers by combining Co-59 Ferromagnetic nuclear resonance spectroscopy (FNR) and magneto-optic kerr effect (MOKE) techniques. It is demonstrated that the surface hybridization produces a significant magnetic hardening with respect to a reference Co/Al system and that the molecule-induced effects modify the magnetic properties of entire Co layer, propagating for several nm from the interface. The FNR spectroscopy also reveals a reconstruction of the magnetic environment at the cobalt surface, whose observation in polycrystalline films is especially intriguing. The results shed new and unexpected light on the interfacial physics in such systems, whose understanding necessitates further experimental and theoretical research
Direct observation of a highly spin-polarized organic spinterface at room temperature
The design of large-scale electronic circuits that are entirely
spintronics-driven requires a current source that is highly spin-polarised at
and beyond room temperature, cheap to build, efficient at the nanoscale and
straightforward to integrate with semiconductors. Yet despite research within
several subfields spanning nearly two decades, this key building block is still
lacking. We experimentally and theoretically show how the interface between Co
and phthalocyanine molecules constitutes a promising candidate. 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 molecules's nitrogen pi orbitals, which substantiates an
ab-initio theoretical description of highly spin-polarised charge conduction
across the interface due to differing spinterface formation mechanims 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
Controlling spins in adsorbed molecules by a chemical switch
The development of chemical systems with switchable molecular spins could lead to the architecture of materials with controllable magnetic or spintronic properties. Here, we present conclusive evidence that the spin of an organometallic molecule coupled to a ferromagnetic substrate can be switched between magnetic off and on states by a chemical stimulus. This is achieved by nitric oxide (NO) functioning as an axial ligand of cobalt(II)tetraphenylporphyrin (CoTPP) ferromagnetically coupled to nickel thin-film (Ni(001)). On NO addition, the coordination sphere of Co2+ is modified and a NO–CoTPP nitrosyl complex is formed, which corresponds to an off state of the Co spin. Thermal dissociation of NO from the nitrosyl complex restores the on state of the Co spin. The NO-induced reversible off–on switching of surface-adsorbed molecular spins observed here is attributed to a spin trans effect
Organic spintronics : pumping spins through polymers
Spin pumping and spin-to-charge conversion in hybrid metal–organic devices reveal the physical mechanisms at work in semiconducting polymers