Unexpected origin of magnetism in monoclinic Nb12O29 from first-principles calculations

Nb12O29 is a 4d transition metal oxide that occurs in two forms with different symmetries, monoclinic (m) and orthorhombic (o). The monoclinic form has unusual magnetic properties; below a temperature of 12 K, it exhibits both metallic conductivity and antiferromagnetic ordering. Here, first-principles density-functional theory calculations are...

Crystal fields, disorder, and antiferromagnetic short-range order in Yb0.24Sn0.76Ru

We report extensive measurements on a new compound (Yb0.24Sn0.76)Ru that crystallizes in the cubic CsCl structure. Valence-band photoemission (PES) and L3 x-ray absorption show no divalent component in the 4f configuration of Yb. Inelastic neutron scattering (INS) indicates that the eight-fold degenerate J-multiplet of Yb3+ is split by the...

Superconductivity at 2.3 K in the misfit compound (PbSe)1.16(TiSe2)2

The structural misfit compound (PbSe)1.16(TiSe2)2 is reported. It is a superconductor with a Tc of 2.3 K. (PbSe)1.16(TiSe2)2 derives from a parent compound, TiSe2, which shows a charge-density wave transition and no superconductivity. The crystal structure, characterized by high-resolution electron microscopy and powder x-ray diffraction,...

Superconductivity in CuxBi2Se3 and its Implications for Pairing in the Undoped Topological Insulator

Bi2Se3 is one of a handful of known topological insulators. Here we show that copper intercalation in the van der Waals gaps between the Bi2Se3 layers, yielding an electron concentration of ?2×1020??cm-3, results in superconductivity at 3.8 K in CuxBi2Se3 for 0.12?x?0.15. This demonstrates that Cooper pairing is possible in Bi2Se3 at accessible...

Insulator to correlated metal transition in V1?xMoxO2

Although many materials display the transition from insulating to metallic behavior on doping, only a few, such as VO2, have the right combination of crystal structure and physical properties to serve as model systems. Here we report the electronic and structural characteristics of the insulator to metal transition in V1?xMoxO2, which we have...

Extreme sensitivity of superconductivity to stoichiometry in Fe1+?Se

The recently discovered iron arsenide superconductors appear to display a universal set of characteristic features, including proximity to a magnetically ordered state and robustness of the superconductivity in the presence of disorder. Here we show that superconductivity in Fe1+?Se, which can be considered the parent compound of the...

Tuning the charge density wave and superconductivity in CuxTaS2

We report the characterization of layered 2H-type CuxTaS2 for 0?x?0.12. The charge density wave (CDW), at 70 K for TaS2, is destabilized with Cu doping. The sub-1 K superconducting transition in undoped 2H-TaS2 jumps quickly to 2.5 K at low x, increases to 4.5 K at the optimal composition Cu0.04TaS2, and then decreases at higher x. The...

Structures and thermoelectric properties of the infinitely adaptive series (Bi2)m(Bi2Te3)n

Superconductivity in noncentrosymmetric Mg10Ir19B16

Mg10Ir19B16, a previously unreported compound in the Mg-Ir-B chemical system, is found to be superconducting at temperatures near 5 K. The fact that the compound exhibits a range of superconducting temperatures between 4 and 5 K suggests that a range of stoichiometries is allowed, though no structural evidence for this is observed. The compound...

Ferromagnetism below 10 K in Mn-doped BiTe

Ferromagnetism is observed below 10 K in [Bi0.75Te0.125Mn0.125]Te. This material has the BiTe structure, which is made from the stacking of two Te-Bi-Te-Bi-Te blocks and one Bi-Bi block per unit cell. Crystal structure analysis shows that Mn is localized in the Bi2 blocks, and is accompanied by an equal amount of TeBi antisite occupancy in the...

Crystal structure and elementary properties of NaxCoO2 ( x=0.32 , 0.51, 0.6, 0.75, and 0.92) in the three-layer NaCoO2 family

Nanometer structural columns and frustration of magnetic ordering in Nb12O29

Coupling between electronic and structural degrees of freedom in the triangular lattice conductor NaxCoO2

Sodium ion ordering in NaxCoO2: Electron diffraction study

Charge Ordering, Commensurability, and Metallicity in the Phase Diagram of the Layered NaxCoO2

Enhancement of metallic behavior in bismuth cobaltates through lead doping

Synthesis and characterization of Ba3(Pb1-xBix)2O7