We investigate the electronic structure of a noncentrosymmetric superconductor, BiPd using photoemission spectroscopy with multiple photon energies ranging from ultraviolet to hard x-ray. Experimental data exhibit interesting difference in the surface and bulk electronic structures of this system. While the surface Bi core level peaks appear at lower binding energies, the surface valence band features are found at the higher binding energy side of the bulk valence band; valence band is primarily constituted by the Pd 4d states.These changes in the electronic structure cannot be explained by the change in ionicity of the constituent elements via charge transfer. Analysis of the experimental data indicates that the Bi-Pd hybridization physics plays the key role in deriving the anomalous spectral evolution and the electronic properties of this system.

Two-dimensional (2D) alloys represent a versatile platform that extends the properties of atomically thin transition-metal dichalcogenides. Here, using molecular beam epitaxy, we investigate the growth of 2D vanadium-molybdenum diselenide alloys, VxMo1-xSe2, on highly oriented pyrolytic graphite and unveil their structural, chemical, and electronic integrities via measurements by scanning tunneling microscopy/spectroscopy, synchrotron X-ray photoemission, and X-ray absorption spectroscopy (XAS). Essentially, we found a critical value of x = similar to 0.44, below which phase separation occurs and above which a homogeneous metallic phase is favored. Another observation is an effective increase in the density of mirror twin boundaries of constituting MoSe2 in the low V concentration regime (x <= 0.05). Density functional theory calculations support our experimental results on the thermal stability of 2D VxMo1-xSe2 alloys and suggest an H phase of the homogeneous alloys with alternating parallel V and Mo strips randomly in-plane stacked. Element-specific XAS of the 2D alloys, which clearly indicates quenched atomic multiplets similar to the case of 2H-VSe2, provides strong evidence for the H phase of the 2D alloys. This work provides a comprehensive understanding of the thermal stability, chemical state, and electronic structure of 2D VxMo1-xSe2 alloys, useful for the future design of 2D electronic devices.

High-quality, large-area epitaxial graphene can be grown on metal surfaces, but its transport properties cannot be exploited because the electrical conduction is dominated by the substrate. Here we insulate epitaxial graphene on Ru(0001) by a stepwise intercalation of silicon and oxygen, and the eventual formation of a SOD2 layer between the graphene and the metal. We follow the reaction steps by X-ray photoemission spectroscopy and demonstrate the electrical insulation using a nanoscale multipoint probe technique.

Using low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), scanning tunneling microscopy (STM), and high-resolution photoelectron spectroscopy (HR-PES) techniques we have studied the annealing effect of one silicon monolayer deposited at room temperature onto a Ni (111) substrate. The variations of the Si surface concentration, recorded by AES at 300 °C and 400 °C, show at the beginning a rapid Si decrease followed by a slowing down up to a plateau equivalent to about one third of a silicon monolayer. STM images and LEED patterns, both recorded at room temperature just after annealing, reveal the formation of an ordered hexagonal superstructure of (?3×?3)R30? type. From these observations and from a quantitative analysis of HR-PES data, recorded before and after annealing, we propose that the (?3×?3)R30? superstructure corresponds to a two-dimensional Ni2Si surface silicide.

WestudytheeffectofSbsubstitutionforPrinthehole-dopedsystemPr0.67Ba0.33MnO3 (PBMO)for different dopinglevelsofSb.Thetwoelectricalresistivitytransitionsobservedinthepristinesample PBMOshifttolowtemperaturesonSbdopingwithanoverallincreaseintheelectricalresistivity.The significantlocallatticedistortionandthegrainboundaryeffectscausedbythelargecationsize mismatchbetweenPr3+ and Sb3+ suppressesthedouble-exchange(DE)interactionandenhancesthe super-exchange(SE)interaction.Thecompoundsshowasignificantandincreasingvalueof magnetoresistanceattemperaturesbelowtheCurietemperature,notexpectedfromtheDEmodel. The CurietemperaturedecreaseswithincreaseinSbcontentbutthesaturationmagnetizationislittle affectedbythesubstitution.Thespins,however,staywellalignedinthelow-temperatureregime.Our X-raynear-edgeabsorptionspectra(XANES)andcorelevelphotoemission(XPS)dataclearlyshowthe Sb cationtobein+3stateandruleoutanypossibilityofe-dopinginourcompounds.