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Graphene-spaced magnetic systems with antiferromagnetic exchange-coupling offer exciting opportunities for emerging technologies. Unfortunately, the in-plane graphene-mediated exchange-coupling found so far is not appropriate for realistic exploitation, due to being weak, being of complex nature, or requiring low temperatures. Here we establish that ultra-thin Fe/graphene/Co films grown on Ir(111) exhibit robust perpendicular antiferromagnetic exchange-coupling, and gather a collection of magnetic properties well-suited for applications. Remarkably, the observed exchange coupling is thermally stable above room temperature, strong but field controllable, and occurs in perpendicular orientation with opposite remanent layer magnetizations. Atomistic first-principles simulations provide further ground for the feasibility of graphene-spaced antiferromagnetic coupled structures, confirming graphene’s direct role in sustaining antiferromagnetic superexchange-coupling between the magnetic films. These results provide a path for the realization of graphene-based perpendicular synthetic antiferromagnetic systems, which seem exciting for fundamental nanoscience or potential use in spintronic devices. Antiferromagnetic spintronics may pave the way to innovative information storage devices with perpendicular coupling, however experimental demonstrations are still sparse. Here, the authors demonstrate a graphene-mediated perpendicular antiferromagnetic coupling between Fe and Co layers in a Fe/graphene/Co sandwich structure.

Effective models focused on pertinent low-energy degrees of freedom have substantially contributed to our qualitative understanding of quantum materials. An iconic example, the Kondo model, was key to demonstrating that the rich phase diagrams of correlated metals originate from the interplay of localized and itinerant electrons. Modern electronic structure calculations suggest that to achieve quantitative material-specific models, accurate consideration of the crystal field and spin-orbit interactions is imperative. This poses the question of how local high-energy degrees of freedom become incorporated into a collective electronic state. Here, we use resonant inelastic x-ray scattering (RIXS) on CePd 3 to clarify the fate of all relevant energy scales. We find that even spin-orbit excited states acquire pronounced momentum-dependence at low temperature—the telltale sign of hybridization with the underlying metallic state. Our results demonstrate how localized electronic degrees of freedom endow correlated metals with new properties, which is critical for a microscopic understanding of superconducting, electronic nematic, and topological states. The fate of high-energy degrees of freedom, such as spin-orbit interactions, in the coherent state of Kondo lattice materials remains unclear. Here, the authors use resonant inelastic x-ray scattering in CePd 3 to show how Kondo-quasiparticle excitations are renormalized and develop a pronounced momentum dependence, while maintaining a largely unchanged spin-orbit gap.

Platelets of strontium hexaferrite (SrFe 12 O 19 , SFO), up to several micrometers in width, and tens of nanometers thick have been synthesized by a hydrothermal method. They have been studied by a combination of structural and magnetic techniques, with emphasis on Mössbauer spectroscopy and X-ray absorption based-measurements including spectroscopy and microscopy on the iron-L edges and the oxygen-K edge, allowing us to establish the differences and similarities between our synthesized nanostructures and commercial powders. The Mössbauer spectra reveal a greater contribution of iron tetrahedral sites in platelets in comparison to pure bulk material. For reference, high-resolution absorption and dichroic spectra have also been measured both from the platelets and from pure bulk material. The O-K edge has been reproduced by density functional theory calculations. Out-of-plane domains were observed with 180° domain walls less than 20 nm width, in good agreement with micromagnetic simulations.

Reaching the van Hove singularity (VHS) in a material enables the emergence of exotic electronic and magnetic phases, such as superconductivity and the quantum anomalous Hall effect. This is demonstrated in cuprates, magic‐angle bilayer graphene, and more recently, monolayer graphene interfaced with alkali and rare earth elements. Here, the europium density at the graphene/rhenium interface is modulated to tune the electron doping level in monolayer graphene across the VHS point, forming either a dense or diluted europium phase. The dense phase enables flat bands at the Fermi level, while graphene remains decoupled from the Re(0001) substrate in both cases. The Dirac point is shifted over 1.5 eV below the Fermi level, and europium lifts the degeneracy of the Dirac cones: one branch hybridizes with Eu 4f states, the other retains Dirac‐like dispersion, as corroborated by density functional theory. X‐ray absorption spectroscopy reveals a mixed Eu(II)/Eu(III) valence state in the dense phase and the persistence of Eu magnetic response up to room temperature in both. The intercalated phases exhibit exceptional thermal stability, with the diluted phase stable up to 960 K. These results highlight the potential of rare‐earth‐doped graphene for engineering flat bands, tunable Dirac‐cone splitting, and robust interfacial magnetism. The modulation of europium density at the graphene/rhenium interface enables electron doping of monolayer graphene both beneath and beyond the van Hove singularity. The interfacial europium is ferromagnetic, with a transition from a mixed Eu(II)/Eu(III) valence in the dense phase to a pure Eu(II) state in the diluted phase. Strong Re‐Eu interaction ensures exceptional thermal stability and potential applications.

Amorphous Nd-Co films deposited by DC-magnetron sputtering presented perpendicular magnetic anisotropy (PMA) with energies, KN, of the order of 106 erg/cc at RT. To understand the origin of their PMA, we measured the orbital and spin magnetic moments in Co and Nd by XMCD at the Co L3,2 and Nd M5,4 edges in two kinds of samples of similar thickness (30 nm) and composition: one compositionally modulated Nd/Co film (CM) with strong PMA (KN ~107 erg/cc at 10 K) and a homogenous alloy (A) with not strong enough PMA to see stripe domains for such thickness. The XMCD analysis evidenced the significant role of Nd in the PMA of these films.

Integrating UHV (ultra high vacuum) and superconducting magnets poses special challenges to the magnet designer. A range of HTS (High Temperature Superconducting) magnets have been developed for UHV synchrotron beamline applications providing users with compact powerful cryogen-free solutions. Recent examples include HTS magnets for LARIAT (Large Area Rapid Imaging Analytical Tool) [8.5 T with 110 mm warm bore], x-ray scattering experiments at BESSY and LNLS [5-6 T with 110 degrees scattering angle aperture], x-ray magnetic circular dichroism, and resonant scattering experiments at ALBA. This paper will focus on the in-UHV HTS magnet installed at ALBA.

We conducted x-ray absorption (XAS) and magnetic circular dichroism (XMCD) measurements at the Co \\(L_{2,3}\\) edges on single crystals of the Kitaev candidate honeycomb lattice compound BaCo\\(_2\\)(AsO\\(_4\\))\\(_2\\). The measurements employed the inverse partial fluorescence yield technique, which is ideal for acquiring reliable x-ray absorption spectra from highly insulating samples, enabling precise quantitative analysis. Our experimental results revealed a significant linear dichroic signal, indicating strong trigonal distortion in the CoO\\(_{6}\\) octahedra in BaCo\\(_2\\)(AsO\\(_4\\))\\(_2\\). We performed a detailed analysis of the experimental XAS and XMCD spectra using a full-multiplet configuration-interaction cluster model. This analysis unveiled that the \\(t_{2g}\\) hole density is predominantly localized in the \\(a_{1g}\\) orbital. Through XMCD sum rules and theoretical calculations, we quantified both the spin and orbital magnetic moments. Our study demonstrates that the local electronic structure of the CoO\\(_{6}\\) octahedra displays an effective trigonal distortion of approximately \\(-0.114\\) eV. This distortion is larger than the Co \\(3d\\) spin-orbit coupling constant, emphasizing the crucial impact of local structural distortions on the electronic and magnetic properties of BaCo\\(_2\\)(AsO\\(_4\\))\\(_2\\).

The sensitivity of Circularly polarized X ray Resonant Magnetic Scattering (CXRMS) to chiral asymmetry has been demonstrated. The study was performed on a 2D array of Permalloy (Py) square nanomagnets of 700 nm lateral size arranged in a chess lattice of 1000 nm lattice parameter. Previous X ray Magnetic Circular Dichroism Photoemission Electron microscopy (XMCD-PEEM) images on this sample showed the formation of vortices at remanence and a preference in their chiral state. The magnetic hysteresis loops of the array along the diagonal axis of the squares indicate a non-negligible and anisotropic interaction between vortices. The intensity of the magnetic scattering using circularly polarized light along one of the diagonal axes of the square magnets becomes asymmetric in intensity in the direction transversal to the incident plane at fields where the vortex states are formed. The asymmetry sign is inverted when the direction of the applied magnetic field is inverted. The result is the expected in the presence of an unbalanced chiral distribution. The effect is observed by CXRMS due to the interference between the charge scattering and the magnetic scattering.

Multiple intriguing phenomena have recently been discovered in tetragonal Heusler compounds, where \\(D_{2d}\\) symmetry sets a unique interplay between Dzyaloshinskii-Moriya (DM) and magnetic dipolar interactions. In the prototype \\(D_{2d}\\) compound Mn\\(_{1.4}\\)PtSn, this has allowed the stabilization of exotic spin textures such as first-reported anti-skyrmions or elliptic Bloch-type skyrmions. While less attention has so far been given to the low-field spiral state, this remains extremely interesting as a simplest phase scenario on which to investigate the complex hierarchy of magnetic interactions in this materials family. Here, via resonant small-angle soft x-ray scattering experiments on high-quality single crystals of Mn\\(_{1.4}\\)PtSn at low temperatures, we evidence how the underlying \\(D_{2d}\\) symmetry of the DMI in this material is reflected in its magnetic texture. Our studies reveal the existence of a novel and complex metastable phase, which possibly has a mixed character of both the N\\'{e}el-type cycloid and the Bloch-type helix, that forms at low temperature in zero fields upon the in-plane field training. This hybrid spin-spiral structure has a remarkable tunability, allowing to tilt its orientation beyond high-symmetry crystallographic directions and control its spiral period. These results broaden the reachness of Heusler \\(D_{2d}\\) materials exotic magnetic phase diagram and extend its tunability, thus enhancing a relevant playground for further fundamental explorations and potential applications in energy saving technologies.

We studied the local Ru 4d electronic structure of alpha-RuCl3 by means of polarization dependent x-ray absorption spectroscopy at the Ru-L2,3 edges. We observed a vanishingly small linear dichroism indicating that electronically the Ru 4d local symmetry is highly cubic. Using full multiplet cluster calculations we were able to reproduce the spectra excellently and to extract that the trigonal splitting of the t2g orbitals is -12 \\(\\pm10\\) meV, i.e. negligible as compared to the Ru 4d spin-orbit coupling constant. Consistent with our magnetic circular dichroism measurements, we found that the ratio of the orbital and spin moments is 2.0, the value expected for a Jeff = 1/2 ground state. We have thus shown that as far as the Ru 4d local properties are concerned, alpha-RuCl3 is an ideal candidate for the realization of Kitaev physics.