The coupled electronic-structural modulations of the ligand states in IrTe2 have been studied by x-ray absorption spectroscopy (XAS) and resonant elastic x-ray scattering (REXS). Distinctive preedge structures are observed at the Te-M4,5 (3d → 5p) absorption edge, indicating the presence of a Te 5p -Ir 5d covalent state near the Fermi level. An enhancement of the REXS signal near the Te 3d → 5p resonance at the Q = (1/5, 0, −1/5) superlattice reflection is observed below the structural transition temperature Ts ∼ 280 K. The analysis of the energy-dependent REXS lineshape reveals the key role played by the spatial modulation of the covalent Te 5p -Ir 5d bond-density in driving the stripe-like order in IrTe2, and uncovers its coupling with the charge and/or orbital order at the Ir sites. The similarity between these findings and the charge-ordering phenomenology observed in the high-Tc superconducting cuprates suggests that the iridates may harbor similar exotic phases.PACS numbers: 71.45. Lr, 78.70.Ck, 78.70Dm, 71.20.Be Transition-metal compounds exhibit surprisingly rich electronic and magnetic properties due to the partially filled d orbitals. The fundamental properties of the electronic structure of transition-metal compounds can be described within the Zaanen-Sawatzky-Allen (ZSA) scheme. This differentiates between the Mott-Hubbard regime (U < ∆) and the charge-transfer regime (∆ < U ), depending on the relative balance of the on-site Coulomb interaction U between the d electrons and the chargetransfer energy ∆ between the ligand states and the transition-metal d states [1]. When ∆ approaches zero, the ligand states are almost degenerate in energy with the transition-metal d levels. As a result, the ligand states may participate in those spin, charge, and/or orbital ordering phenomena that are peculiar to the correlated nature of the d-orbitals. As an example of such phenomenology, ordering of the oxygen 2p holes is realized in the stripe-ordered phase of layered cuprates [2-6], or in the ladder-type Cu oxides [7].Very recently, a first-order structural transition was discovered in the 5d transition-metal chalcogenide IrTe 2 at T s ∼ 280 K. This attracted great interest due to the concomitant discovery of superconductivity in the Ptand Pd-substituted or intercalated compounds [8, 9]. Clarifying the origin of the structural phase transition might be a critical step towards the understanding of superconductivity itself; however, to date several mechanisms have been debated, with a universal consensus still lacking. The phase transition is accompanied by the emergence of a superstructure lattice modulation in electron diffraction [9] -with wavevector Q = (1/5, 0, −1/5) as expressed in reciprocal lattice units in tetragonal notation -which is here illustrated in Fig. 1. The main elements are the Ir-Ir dimerization along the a axis with period 5a, and the consequent distortion of the triangular Ir sublattice in the a − b plane, conflating to an overall trigonal-to-triclinic symmetry reduction. The IrIr dimeriza...

Thin films of the ferromagnetic metal SrRuO3 (SRO) show a varying easy magnetization axis depending on the epitaxial strain and undergo a metal-to-insulator transition with decreasing film thickness. We have investigated the magnetic properties of SRO thin films with varying thicknesses fabricated on SrTiO3(001) substrates by soft x-ray magnetic circular dichroism (XMCD) at the Ru M2,3 edge. Results have shown that, with decreasing film thickness, the film changes from ferromagnetic to non-magnetic around 3 monolayer thickness, consistent with previous magnetization and magneto-optical Kerr effect measurements. The orbital magnetic moment perpendicular to the film was found to be ∼ 0.1 µB/Ru atom, and remained nearly unchanged with decreasing film thickness while the spin magnetic moment decreases. Mechanism for the formation of the orbital magnetic moment is discussed based on the electronic structure of the compressively strained SRO film.

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Epitaxial CoFe 2 O 4 /Al 2 O 3 bilayers are expected to be highly efficient spin injectors into Si owing to the spin filter effect of CoFe 2 O 4 . To exploit the full potential of this system, understanding the microscopic origin of magnetically dead layers at the CoFe 2 O 4 /Al 2 O 3 interface is necessary. In this paper, we study the crystallographic and electronic structures and the magnetic properties of CoFe 2 O 4 (111) layers with various thicknesses (thickness d = 1.4, 2.3, 4, and 11 nm) in the epitaxial CoFe 2 O 4 (111)/Al 2 O 3 (111)/Si(111) structures using soft X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) combined with cluster-model calculation. The magnetization of CoFe 2 O 4 measured by XMCD gradually decreases with decreasing thickness d and finally a magnetically dead layer is clearly detected at d = 1.4 nm. The magnetically dead layer has frustration of magnetic interactions which is revealed from comparison between the magnetizations at 300 and 6 K. From analysis using configuration-interaction cluster-model calculation, the decrease of d leads to a

We have studied magnetism in anatase Ti1−xCoxO 2−δ (x = 0.05) thin films with various electron carrier densities, by soft x-ray magnetic circular dichroism (XMCD) measurements at the Co L2,3 absorption edges. For electrically conducting samples, the magnetic moment estimated by XMCD was < 0.3 µB/Co using the surface-sensitive total electron yield (TEY) mode, while it was 0.3-2.4 µB/Co using the bulk-sensitive total fluorescence yield (TFY) mode. The latter value is in the same range as the saturation magnetization 0.6-2.1 µB/Co deduced by SQUID measurement. The magnetization and the XMCD intensity increased with carrier density, consistent with the carrierinduced origin of the ferromagnetism.Semiconductors partially substituted with magnetic ions are called diluted magnetic semiconductors (DMSs) and are expected to be useful in spintronics devices, where electron spins can be controlled by electric field and/or by photons. Ferromagnetic DMS's with Curie temperatures (T C 's) higher than room temperature are highly desirable for the development of spintronic devices. To date, much work in this area has been done, mainly on II-VI and III-V compounds doped with magnetic ions such as (Cd,Mn)Te [1] and (Ga,Mn)As [2,3], but their T C