Molecular semiconductors may exhibit antiferromagnetic correlations well below room temperature. Although inorganic antiferromagnetic layers may exchange bias single-molecule magnets, the reciprocal effect of an antiferromagnetic molecular layer magnetically pinning an inorganic ferromagnetic layer through exchange bias has so far not been observed. We report on the magnetic interplay, extending beyond the interface, between a cobalt ferromagnetic layer and a paramagnetic organic manganese phthalocyanine (MnPc) layer. These ferromagnetic/organic interfaces are called spinterfaces because spin polarization arises on them. The robust magnetism of the Co/MnPc spinterface stabilizes antiferromagnetic ordering at room temperature within subsequent MnPc monolayers away from the interface. The inferred magnetic coupling strength is much larger than that found in similar bulk, thin or ultrathin systems. In addition, at lower temperature, the antiferromagnetic MnPc layer induces an exchange bias on the Co film, which is magnetically pinned. These findings create new routes towards designing organic spintronic devices.

We carried out measurements of domain wall (DW) velocities driven by magnetic field pulses in symmetric Pt/Co/Pt and asymmetric Pt/Co/AlOx, Pt/Co/GdOx and Pt/Co/Gd trilayers with ultrathin Co layers and perpendicular magnetic anisotropy. In agreement with theoretical models, the maximum observed velocity is much larger in the asymmetric samples, where the interfacial Dzyaloshinskii-Moriya interaction (DMI) stabilises chiral Néel walls, than in the symmetric stack. In addition, in Pt/Co/Gd very large DW speeds (up to 600 m/s) are obtained, 2.5 times larger than in samples with oxidised Gd. Magnetic measurements reveal that this may be explained by the anti-parallel coupling between the magnetic moments of Gd and Co at the Gd/Co interface, leading to a decrease of the total magnetisation. In quantitative agreement with analytical models, in all samples the maximum observed DW speed scales as D/Ms, where D is the strength of the DMI and Ms the spontaneous magnetisation.

The DEIMOS (Dichroism Experimental Installation for Magneto-Optical Spectroscopy) beamline was part of the second phase of the beamline development at French Synchrotron SOLEIL (Source Optimisée de Lumière à Energie Intermédiaire du LURE) and opened to users in March 2011. It delivers polarized soft x-rays to perform x-ray absorption spectroscopy, x-ray magnetic circular dichroism, and x-ray linear dichroism in the energy range 350-2500 eV. The beamline has been optimized for stability and reproducibility in terms of photon flux and photon energy. The main end-station consists in a cryo-magnet with 2 split coils providing a 7 T magnetic field along the beam or 2 T perpendicular to the beam with a controllable temperature on the sample from 370 K down to 1.5 K.

Mn 3 Ga bulk material and thin films deposited on several different substrates have been investigated using x-ray and neutron diffraction, x-ray absorption spectroscopy, x-ray magnetic circular dichroism, and electronic structure calculations using density-functional theory with the aim of determining the atomic site occupancy, magnetic moments, and magnetic structure of this tetragonal D0 22 -structure compound. The Mn 3 Ga has close to ideal site occupancy, with Ga on 2a sites and Mn on 2b and 4d sites. The magnetic structure is basically ferrimagnetic, with the larger Mn moment of about 3 μ B on the 2b site, which is coordinated by 8 Mn 4d and 4 Ga, and the smaller one on the 4d site, which is coordinated by 4 Mn 2b, 4 Ga, and 4 Mn 4d. The Mn d-band occupancy is close to 5 on both sites, and the orbital moments are small, <0.2 μ B . The material nevertheless exhibits substantial uniaxial anisotropy, K u = 1.0 MJ m −3 , which originates from the 4d site. The 2b site has hard axis anisotropy, which together with an oscillatory exchange coupling from the first and second nearest neighbors, leads to a soft component of the magnetization in the c plane, coexisting with c-axis hysteresis loops exhibiting coercivity of up to 1.2 T, and magnetization in the range 110-220 kA m −1 at room temperature, depending on preparation conditions. Tetragonal Mn 2 Ga films behave similarly. Manganese is lost from both sites, but the films have substantially larger magnetization (480 kA m −1 ) and anisotropy constant (2.35 MJ m −3 ) than Mn 3 Ga.

Understanding the properties of spin-crossover molecules in direct contact with metals is crucial for their future integration in electronic and spintronic devices. By X-ray absorption spectroscopy, we investigate the properties of Fe II ((3,5-(CH 3 ) 2 Pz) 3 BH) 2 molecules in the form of monolayer islands on a metallic substrate, namely, Au(111). We demonstrate that the spincrossover transition can be thermally induced from the high spin state to a mixed spin state phase containing one-third of high-spinstate and two-thirds of low-spin-state molecules in agreement with previous work by scanning tunneling microscopy. In addition, at 4.4 K, the spin crossover from the low spin state to the high spin state can also be induced by X-ray and by light excitations.