Epitaxial graphene on Ir(111) prepared in excellent structural quality is investigated by angle-resolved photoelectron spectroscopy. It clearly displays a Dirac cone with the point shifted only slightly above Fermi level. The moiré resulting from overlaid and surface lattices imposes superperiodic potential giving rise to replicas opening of minigaps band structure.

The electronic structure basis of the extremely large magnetoresistance in layered nonmagnetic tungsten ditelluride has been investigated by angle-resolved photoelectron spectroscopy. Hole and electron pockets approximately same size were found at low temperatures, suggesting that carrier compensation should be considered primary source effect. material exhibits a highly anisotropic Fermi surface from which pronounced anisotropy follows. A change with temperature was high-density-of-states...

Abstract A long-standing issue in topological insulator research has been to find a bulk single crystal material that provides high-quality platform for characterizing surface states without interference from electronic states. This would ideally be insulator, have state Dirac point energy well isolated the valence and conduction bands, display quantum oscillations electrons growable as large, crystals. Here we show this obstacle is overcome by crystals of lightly Sn-doped Bi 1.1 Sb 0.9 Te 2...

Nodal-line semimetals (NLSs) represent a new type of topological semimetallic phase beyond Weyl and Dirac in the sense that they host closed loops or open curves band degeneracies Brillouin zone. Parallel to classification type-I type-II semimetals, there are two types NLSs. The NLS has been proposed realized many compounds, whereas exotic strongly violates Lorentz symmetry remained elusive. First-principles calculations show Mg3Bi2 is material candidate for NLS. crossing close Fermi level...

Magnetism, when combined with an unconventional electronic band structure, can give rise to forefront properties such as the quantum anomalous Hall effect, axion electrodynamics, and Majorana fermions. Here we report characterization of high-quality crystals EuSn2P2, a new material specifically designed engender states plus magnetism. EuSn2P2 has layered, Bi2Te3-type structure. Ferromagnetic interactions dominate Curie-Weiss susceptibility, but transition antiferromagnetic ordering occurs...

Angle resolved photoelectron spectroscopy (ARPES) is extensively used to characterize the dependence of electronic structure graphene on Ir(111) preparation process. ARPES findings reveal that temperature programmed growth alone or in combination with chemical vapor deposition leads displaying sharp bands. The photoemission intensity Dirac cone monitored as a function increasing area. Electronic features moir\'e superstructure present system, namely minigaps and replica bands are examined...

The success of black phosphorus in fast electronic and photonic devices is hindered by its rapid degradation the presence oxygen. Orthorhombic tin selenide a representative group IV-VI binary compounds that are robust isoelectronic share same structure with phosphorus. We measure band SnSe find highly anisotropic valence bands form several valleys having dispersion within layers negligible across. This exactly desired for efficient thermoelectric generation where has shown great promise.

In cuprate superconductors, the doping of carriers into parent Mott insulator induces superconductivity and various other phases whose characteristic temperatures are typically plotted versus level p. most materials, p cannot be determined from chemical composition, but it is derived superconducting transition temperature, Tc, using assumption that Tc dependence on universal. Here, we present angle-resolved photoemission studies Bi2Sr2CaCu2O8+δ, cleaved annealed in vacuum or ozone to reduce...

Significance Surfaces are gates to control the transport of energy and materials between gas phase bulk. For hydrogen storage, across surface is recognized as bottleneck, e.g., 1 H 2 in 1,000 impinging a Pd penetrates surface. Here, we demonstrate that alloying Pd(110) with submonolayer amounts Au dramatically accelerates absorption, by factor more than 40. This discovery will lead enhancement absorption kinetics, thereby improving performance hydrogen-purifying membranes hydrogen-storage...

We report that 1T-TiSe2, an archetypical layered transition metal dichalcogenide, becomes superconducting when Ta is substituted for Ti but not Nb Ti. This unexpected because and should be chemically equivalent electron donors. Superconductivity emerges near x = 0.02 Ti1–xTaxSe2, while, Ti1–xNbxSe2, no transitions are observed above 0.4 K. The chemical nature of the dopants confirmed by X-ray photoelectron spectroscopy. ARPES Raman scattering studies show similarities differences between two...

Proximity-induced superconductivity in a 3D topological insulator represents new avenue for observing zero-energy Majorana fermions inside vortex cores. Relatively small gaps and low transition temperatures of conventional s-wave superconductors put the hard constraints on these experiments. Significantly larger higher cuprate might be an attractive alternative to considerably relax constraints, but it is not clear whether proximity effect would effective heterostructures involving cuprates...

EuMg2Bi2 has been investigated to understand the electronic and magnetic behaviors as an antiferromagnetic (AFM) topological semimetal candidate. High-quality single crystals of were grown via a Bi flux and, subsequently, characterized be consistent with previously reported bulk resistivity properties. A ferromagnetic interaction is indicated by positive Curie–Weiss temperature obtained through fitting susceptibility data. The measurements reveal interesting behavior that potentially...

We have performed combined angle-resolved photoemission spectroscopy (ARPES) experiments and density functional theory (DFT) calculations of the electronic structure Ir(111) surface, with focus on existence energy band gaps. The investigation was motivated by experimental results suggesting as an ideal support for growth weakly bonded graphene. Therefore, our prime interest around symmetry point. In accordance DFT calculations, ARPES has shown a wide gap shape parallelogram centred Within...

Topological crystalline insulators represent a novel topological phase of matter in which the surface states are protected by discrete point group symmetries underlying lattice. Rock-salt lead-tin-selenide alloy is one possible realization this phase, undergoes transition upon changing lead content. We used scanning tunneling microscopy (STM) and angle resolved photoemission spectroscopy (ARPES) to probe on (001) Pb${}_{1\ensuremath{-}x}$Sn${}_{x}$Se topologically nontrivial ($x=0.23$)...

We analyze renormalization of the ${\ensuremath{\pi}}^{*}$ band $n$-doped epitaxial graphene on Ir(111) induced by electron-phonon coupling. Our procedure extracting bare relies recursive self-consistent refining functional form until convergence. demonstrate that components self-energy, as well spectral intensity obtained from angle-resolved photoelectron spectroscopy, show is due to coupling two distinct phonon excitations. From velocity and an increase imaginary part self-energy we find...

Narrow gap semiconductor Pb$_{1-x}$Sn$_{x}$Se was investigated for topologically protected surface states in its rock-salt structural phase x=0.45, 0.23, 0.15, and 0. Angle-resolved photoelectron spectroscopy of intrinsically p-doped samples showed clear indication two Dirac cones, eccentric about the time-reversal invariant point X Brillouin zone all but x=0 sample. Adsorption alkalies gradually filled bands with electrons, driving x>0 topological crystalline insulator systems through...

It is common knowledge that even a trace amount of chemisorbed species can strongly perturb the surface electronic structure, in particular states, to point their complete eradication. We have confirmed this behavior by adsorbing Li on Ir(111), but surprisingly, we discovered presence graphene does not suppress Ir state. By combining results low-energy electron diffraction and angle-resolved photoemission spectroscopy with density functional theory for modeling studied systems provide...

A comparative study of the properties topological insulator Bi2Te2Se (BTS) crystals grown by vertical Bridgeman method is described. Two defect mechanisms that create acceptor impurities to compensate for native n-type carriers are compared: Bi excess, and light Sn doping. Both methods yield low carrier concentrations an n-p crossover over length crystal boules, but lower higher resistivities obtained Sn-doped crystals, which reach as 8 × 1014 cm−3. Further, temperature dependent display...

We report a new, cleavable, strong topological metal, ${\mathrm{Zr}}_{2}{\mathrm{Te}}_{2}\mathrm{P}$, which has the same tetradymite-type crystal structure as insulator $\mathrm{B}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{2}\mathrm{Se}$. Instead of being semiconductor, however, ${\mathrm{Zr}}_{2}{\mathrm{Te}}_{2}\mathrm{P}$ is metallic with pseudogap between 0.2 and 0.7 eV above Fermi energy $({E}_{F})$. Inside this pseudogap, two Dirac dispersions are predicted: one surface-originated cone...

Three-dimensional topological insulators and crystalline represent new quantum states of matter, which are predicted to have insulating bulk spin-momentum-locked gapless surface states. Experimentally, it has proven difficult achieve the high resistivity that would allow dominate transport properties over a substantial temperature range. Here we report series indium-doped ${\mathrm{Pb}}_{1\ensuremath{-}x}{\mathrm{Sn}}_{x}\mathrm{Te}$ compounds manifest huge resistivities together with...

Nodal-line semimetals (NLSs) represent a new type of topological semimetallic beyond Weyl and Dirac in the sense that they host closed loops or open curves band degeneracies Brillouin zone. Parallel to classification type-I type-II semimetals, there are two types NLSs. The conventional NLS phase, which bands forming nodal line have opposite signs for their slopes along any direction perpendicular line, has been proposed realized many compounds, whereas exotic is very rare. Our...

We report the characterization of misfit compound (Pb1−xSnxSe2)1.16(TiSe2)2 for 0 ≤ x 0.6, in which a [100] rocksalt-structure bilayer Pb1−xSnxSe, is topological crystalline insulator bulk form, alternates with double layer normally non-superconducting transition metal dichalcogenide TiSe2. The dependence Tc displays weak dome-like shape maximum 4.5 K at = 0.2; there only subtle change composition where trivial to occurs Pb1−xSnxSe. present superconductor 0.4, Pb1−xSnxSe phase regime. For...

The valence band (VB) structure of an Al0.5TiZrPdCuNi high-entropy alloy (HEA) obtained using x-ray photoelectron spectroscopy has been compared to that recently calculated by Odbadrakh et al. [J. Appl. Phys. 126, 095104 (2019)]. Both the experimental and theoretical VBs show a split-band structure, typical for alloys consisting early (TE) late (TL) transition metals. Accordingly, several electronic (ES) properties this alloy, both in glassy crystalline state, are with those similar TE-TL...