A high spin polarization of states around the Fermi level, EF, at room temperature has been measured in the past at the interface between a few molecular candidates and the ferromagnetic metal Co. Is this promising property for spintronics limited to these candidates? Previous reports suggested that certain conditions, such as strong ferromagnetism, i.e., a fully occupied spin-up d band of the ferromagnet, or the presence of π bonds on the molecule, i.e., molecular conjugation, needed to be met. What rules govern the presence of this property? We have performed spin-resolved photoemission spectroscopy measurements on a variety of such interfaces. We find that this property is robust against changes to the molecule and ferromagnetic metal's electronic properties, including the aforementioned conditions. This affirms the generality of highly spin-polarized states at the interface between a ferromagnetic metal and a molecule and augurs bright prospects toward integrating these interfaces within organic spintronic devices.

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Ferromagnetic films evaporated at oblique incidence show invariably an uniaxial in-plane magnetic anisotropy component with easy axis perpendicular to the incidence plane. Scanning Tunneling Microscopy (STM) images reveal that oblique deposition results in rough films with highly anisotropic correlation functions of the surface profile. We show that simple shape anisotropy calculations using high-quality STM roughness data as input reproduce the measured anisotropies remarkably well and unambiguously relate them to the long-ranged dipolar interactions.

Ultrathin Fe films were epitaxially grown at room temperature on GaAs(001) with either predominant (4×2) or (2×6) surface reconstruction. At nominal Fe coverages of tFe⩾2.8 monolayers (ML), a ferromagnetic state is observed below a certain critical temperature, TC. Surprisingly, the magnetic phase transition at TC appears even sharper than for Fe films on metallic single-crystal substrates, which were believed to be an excellent representation of two-dimensional (2D) ferromagnets. This may be due to the extremely short lateral length scale of film inhomogeneities. The critical exponent β=0.26 is close to the value expected for 2D XY systems of finite size. For tFe=3.6 ML, TC is close to room temperature. TC decreases steeply with decreasing Fe coverage, with an average slope of 270 K/ML. From a power law extrapolation, TC seems to vanish at tFe=2.5 ML. The onset of ferromagnetism at tFe=2.5 ML is interpreted as a percolation phenomenon during the coalescence process of Fe islands.

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