Linear-polarized soft-x-ray absorption ͑XAS͒ and inelastic neutron scattering ͑INS͒ experiments have been performed on CeMIn 5 with M = Rh, Ir, and Co to determine the crystal-field scheme and characteristic Kondo temperatures T ‫ء‬ for the hybridization between 4f and conduction electrons. The ground-state wave functions are determined from the polarization-dependent soft-XAS data at the cerium M 4,5 edge and the crystal-field splittings from INS. The characteristic temperature T ‫ء‬ has been determined from the line widths of the neutron scattering data. We find that the quasielastic linewidths of the superconducting compounds CeCoIn 5 and CeIrIn 5 are comparable with the low-energy crystal-field splitting.

We report on investigations of the static structure factors of glass-forming Zr-Cu alloy melts by combination of the containerless processing technique of electrostatic levitation with diffraction of neutron and synchrotron radiation. The partial Bhatia-Thornton structure factors SNN and SNC were determined from the two total structure factors. While it is widely assumed in literature that the good glass-forming ability of Zr-Cu is related to an icosahedral short-range order prevailing in the melt, our partial structure factors demonstrate that the liquid Zr-Cu is not characterized by a dominant icosahedral short-range order.

We report on our investigation of the electronic structure of Ti 2 O 3 using (hard) x-ray photoelectron and soft x-ray absorption spectroscopy. From the distinct satellite structures in the spectra, we have been able to establish unambiguously that the Ti-Ti c-axis dimer in the corundum crystal structure is electronically present and forms an a 1g a 1g molecular singlet in the low-temperature insulating phase. Upon heating, we observe a considerable spectral weight transfer to lower energies with orbital reconstruction. The insulatormetal transition may be viewed as a transition from a solid of isolated Ti-Ti molecules into a solid of electronically partially broken dimers, where the Ti ions acquire additional hopping in the a-b plane via the e π g channel, the opening of which requires consideration of the multiplet structure of the on-site Coulomb interaction. The role of ion pair formation for the metal-insulator transition (MIT) in early transition metal oxides, with the octahedra sharing either a common face or a common edge, has been a matter of debate in the past several decades . Based on the presence of the c-axis V-V dimers in the corundum crystal structure of V 2 O 3 , Castellani et al. [4] proposed a molecular singlet model for the a 1g orbitals, projecting the system effectively onto a solid with S ¼ 1=2 entities, which then should carry the essential physics for the MIT and the magnetic structure in the antiferromagnetic insulating phase. However, soft x-ray absorption spectroscopy (XAS) experiments [10] showed that the two d electrons on each Vare in the high-spin S ¼ 1 state, implying that the atomic Hund's rule coupling is much stronger than the intradimer hopping integrals. Furthermore, using band structure calculations, Elfimov et al. [12] found that the intradimer hopping integral is not the most important one; rather, the hopping integrals between second, third, and fourth nearest V neighbors are at least equally important. In other words, the c-axis dimers need not be present electronically, although structurally they are present.Ti 2 O 3 shares much of the same fascination as V 2 O 3 . It also has a corundum crystal structure (see the inset in Fig. 1) and exhibits, upon lowering the temperature, a MIT [22]. The earliest models explained the low-temperature insulating phase of Ti 2 O 3 by assuming a band splitting caused by an antiferromagnetic long-range order [22]. However, in contrast to V 2 O 3 , the transition is gradual and is not accompanied by a structural transition nor magnetic ordering [23][24][25]. Goodenough and Van Zandt et al. also proposed that the short c-axis pair bond length of 2.578 Å at 300 K [26], which is much shorter than in V 2 O 3 , with 2.697 Å at 300 K [27], increases the trigonal crystal

We studied Cu self-dynamics and liquid density of Zr66.7Cu33.3, Zr35.5Cu64.5, Zr36Cu64, and Zr38.2Cu61.8 liquids using a combination of containerless processing techniques and quasielastic neutron scattering. We show that the composition dependence of the Cu self-dynamics is qualitatively controlled by the liquid packing density. It is hence monotonic within a narrow composition range and not sensitive to small composition variations. Similarly, replacing Cu by Ni results in a slower atomic dynamics in the Zr-Ni liquids, as a consequence of the more dense packing. This is in contrast to the strong composition dependence of the glass-forming behaviour, and the better glass-forming ability of the Zr-Cu over Zr-Ni alloys, which usually favours sluggish liquid dynamics. Thus, in the Zr-Cu case, the glass-forming ability is not directly correlated with liquid dynamics and packing density.