Publications de Marco Grioni | EPFL Graph Search

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We present scanning tunneling microscopy (STM) measurements at the TaSe2 surface showing a first order process leading to a surface Mott transition. This metal to insulator transition is triggered by the commensurate charge density wave (CDW) which set up at 475 K. The electronic structure rearrangement due to the new periodicity gives rise to a half filled sub-band prone to the localization phenomena. This transition results fully developed below 250K in agreement with previous photoemission Measurements.

We present a detailed analysis of resonant inelastic x-ray scattering from Fe1.087Te with unprecedented energy resolution. In contrast to the sharp peaks typically seen in insulating systems at the transition-metal L-3 edge, we observe spectra which show d ...

Angle-resolved photoemission spectroscopy (ARPES) and optical measurements were performed on single crystal samples of ZrSe3, HfSe3, and ZrS3, which belong to the class of low-dimensional band insulators. By ARPES, we traced the dispersion of the (S 3p, Se ...

Recent photoemission evidence for non-zero gap in highly overdoped Bi2Sr2-CaCu2O8+x, along the directions in the Brillouin zone where the d-wave gap exhibits nodes, is in accordance with more conventional behavior in strongly overdoped high-T-c cuprates. This differs from underdoped regime, where departures from Fermi-liquid (FL) behavior are found. Observed non-FL linear resistivity up to similar to 1050 K in low-T-c perovskite Sr2RuO4-delta is reminiscent of cuprates and implies some similarities between

A paradigmatic case of multi-band Mott physics including spin-orbit and Hund's coupling is realized in Ca2RuO4. Progress in understanding the nature of this Mott insulating phase has been impeded by the lack of knowledge about the low-energy electronic str ...

Angle-resolved photoemission spectra taken with high energy resolution on the one-dimensional compound (TaSe4)2I confirm the suppression of the spectral intensity at the Fermi edge for one-dimensional systems and lend support to correlation effects as its most probable cause.

The high-T-c cuprate superconductors are close to antiferromagnetic order. Recent measurements of magnetic excitations have reported an intriguing similarity to the spin wavesmagnons- of the antiferromagnetic insulating parent compounds, suggesting that ma ...

Photoemission investigations of quasi-one dimensional materials reveal the unconventional electronic properties of these systems. The normal state spectra are incompatible with a Fermi liquid description, and exhibit features consistent with the Luttinger liquid scenario, which describes correlated fermions in 1D. Specific surface effects, and the tendency to defect-induced localization in these systems, may considerably influence the measured spectral properties.

We discuss recent high-resolution angle-resolved photoemission (ARPES) and time-resolved ARPES experiments on selected surfaces which illustrate the formation of broken-symmetry ground states of very different nature: i) a Mott insulator in the layered dic ...

High-resolution angle-resolved photoemission data show that a metal-insulator Mott transition occurs at the surface of the quasi-two-dimensional compound 1T-TaSe2. The transition is driven by the narrowing of the Ta 5d band induced by a temperature-dependent modulation of the atomic positions. A dynamical mean-field theory calculation of the spectral function of the half-filled Hubbard model captures the main qualitative feature of the data, namely, the rapid transfer of spectral weight from the observed qu

We have exploited the resonant enhancement of the Ce 4f cross section around 120 eV to investigate the nature of the 4f states in CePd3 and CeSb. Our results are qualitatively consistent with the predictions of the Anderson Impurity Model. In CePd3 our high resolution spectra reveal the characteristic many-body spectral features near the Fermi level.

Using angle-resolved photoemission and linearly polarized synchrotron radiation, we measured the electronic band structure of electronic states of CuO2 plane materials ranging from insulators (Sr2CuO2Cl2) to overdoped superconductors (Bi2Sr2CaCu2O8+x). We report three results: (i) The CuO2 containing insulator possesses a spin-density-wave (SDW) ground state; (ii) there are precursors df the SDW state for underdoped Bi2Sr2CaCu2O8+x; (iii) an extended saddle-point-type van Hove singularity is neither a neces

We exploit time- and angle-resolved photoemission spectroscopy to determine the evolution of the out-of-equilibrium electronic structure of the topological insulator Bi2Se3. The response of the Fermi-Dirac distribution to ultrashort IR laser pulses has bee ...

We report on the formation of a BiAg2/Ag/Si(1 1 1) trilayer system which exhibits a giant Rashba spin-splitting of its surface-localized states and is grown on a semiconducting substrate. Angle-resolved photoelectron spectroscopy (ARPES) results reveal the ...

We present a comprehensive angle-resolved photoemission spectroscopy study of Ca1.8Sr0.2RuO4. Four distinct bands are revealed and along the Ru-O bond direction their orbital characters are identified through a light polarization analysis and comparison to ...

We exploited angle-resolved photoemission (ARPES) to investigate the nature of the elementary quasiparticle (QP) excitations in selected low-dimensional compounds. In the model quasi two-dimensional conductor TiTe2, we observe spectral lineshapes which are consistent with a Fermi liquid (FL) scenario, and the usual QP scattering mechanisms. In contrast, in typical quasi one-dimensional Peierls systems like TTF-TCNQ, (TaSe4)(2)I and K0.3MoO3 we find clear non-FL lineshapes. We briefly discuss the possible or

We investigate the polaronic ground state of anatase TiO2 by bulk-sensitive resonant inelastic x-ray spectroscopy (RIXS) at the Ti L-3 edge. We find that the formation of the polaron cloud involves a single 95 meV phonon along the c axis, in addition to th ...

Coherent x-rays are here! This exciting news is a byproduct of the effort to increase the brightness of synchrotron light sources. We discuss the basic issues concerning x-ray coherence, and some of the applications that are already underway - with particular emphasis on those of interest to nanoscience.

The interaction of light with a material's electronic system creates an out-of-equilibrium (non-thermal) distribution of optically excited electrons. Non-equilibrium dynamics relaxes this distribution on an ultrafast timescale to a hot Fermi-Dirac distribu ...

Marco Grioni

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Scanning tunneling microscopy observation of a mott-insulator phase at the 1T-TaSe2 surface

Evidence for core-hole-mediated inelastic x-ray scattering from metallic Fe1.087Te

Probing the nature of the Ce 4f states in CeX9Si4 (X=Ni, Co) by high-energy spectroscopies

Photoemission and optical studies of ZrSe3, HfSe3, and ZrS3

On some common features in high and low-Tc superconducting perovskites

Hallmarks of Hunds coupling in the Mott insulator Ca2RuO4

Photoemission near the Fermi Energy in One Dimension

Anisotropic softening of magnetic excitations along the nodal direction in superconducting cuprates

The spectral properties of quasi-one-dimensional materials: High-resolution ARPES

BROKEN-SYMMETRY STATES AT SURFACES: THE (tr)ARPES VIEW

Spectroscopic signatures of a bandwidth-controlled Mott transition at the surface of 1T-TaSe2

High resolution resonant photoemission of Ce-based materials

Electronic structure of CuO2 planes: From insulator to superconductor

Ultrafast photodoping and effective Fermi-Dirac distribution of the Dirac particles in Bi2Se3

Giant spin-orbit splitting in a surface alloy grown on a Si substrate: BiAg2/Ag/Si(111)

Orbitally selective breakdown of Fermi liquid quasiparticles in Ca1.8Sr0.2RuO4

Fermi liquid and non-Fermi liquid spectral lineshapes in low-dimensional solids

Electron-Phonon Coupling in the Bulk of Anatase TiO2 Measured by Resonant Inelastic X-Ray Spectroscopy

Coherent x-rays in the world of nanoscience

Extracting the temperature of hot carriers in time- and angle-resolved photoemission