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Examining the surface phase diagram of ${\mathrm{IrTe}}_{2}$ with photoemission

Rumo, Maxime ; Nicholson, Christopher W. ; Pulkkinen, Aki ; Hildebrand, Baptiste ; Kremer, Geoffroy ; Salzmann, Björn ; Mottas, Marie-Laure ; Ma, K. Y. ; Wong, E. L. ; Man, M. K. L. ; Dani, K. M. ; Barbiellini, B. ; Muntwiler, Matthias ; Jaouen, Thomas ; Rohr, F. O. von ; Monney, Claude

In: Physical Review B, 2020, vol. 101, no. 23, p. 235120

In the transition metal dichalcogenide IrTe2, low-temperature charge-ordered phase transitions involving Ir dimers lead to the occurrence of stripe phases of different periodicities, and nearly degenerate energies. Bulk-sensitive measurements have shown that, upon cooling, IrTe2 undergoes two such first-order transitions to (5×1×5) and (8×1×8) reconstructed phases at Tc1∼280 K and...

Role of a higher-dimensional interaction in stabilizing charge density waves in quasi-one-dimensional ${\mathrm{NbSe}}_{3}$ revealed by angle-resolved photoemission spectroscopy

Nicholson, Christopher W. ; Schwier, Eike Fabian ; Shimada, K. ; Berger, Helmuth ; Hoesch, M. ; Berthod, C. ; Monney, Claude

In: Physical Review B, 2020, vol. 101, no. 4, p. 045412

We revisit charge density wave (CDW) behavior in the archetypal quasi-one- dimensional (quasi-1D) material NbSe3 by high-resolution angle-resolved photoemission spectroscopy measurements utilizing a microfocused laser with a photon energy of 6.3 eV. We present a detailed view of the electronic structure of this complex multiband system and unambiguously resolve CDW gaps at the Fermi level ...

Phase separation in the vicinity of Fermi surface hot spots

Jaouen, Thomas ; Hildebrand, Baptiste ; Mottas, Marie-Laure ; Giovannantonio, M. Di ; Ruffieux, Pascal ; Rumo, Maxime ; Nicholson, Christopher W. ; Razzoli, E. ; Barreteau, C. ; Ubaldini, A. ; Giannini, E. ; Vanini, Fabiano ; Beck, Hans ; Monney, Claude ; Aebi, Philipp

In: Physical Review B, 2019, vol. 100, no. 7, p. 075152

Spatially inhomogeneous electronic states are expected to be key ingredients for the emergence of superconducting phases in quantum materials hosting charge-density waves (CDWs). Prototypical materials are transitionmetal dichalcogenides (TMDCs) and among them, 1T-TiSe2 exhibiting intertwined CDW and superconducting states under Cu intercalation, pressure, or electrical gating. Although it...

Anisotropic magnetic excitations and incipient N\’eel order in $\mathrm{Ba}{({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x})}_{2}{\mathrm{As}}_{2}$

Garcia, Fernando A. ; Ivashko, Oleh ; McNally, Daniel E. ; Das, Lakshmi ; Piva, Mario M. ; Adriano, C. ; Pagliuso, Pascoal G. ; Chang, Johan ; Schmitt, Thorsten ; Monney, Claude

In: Physical Review B, 2019, vol. 99, no. 11, p. 115118

It is currently understood that high temperature superconductivity (SC) in the transition metal (M) substituted iron arsenides Ba(Fe1−xMx)2As2 is promoted by magnetic excitations with wave vectors (π,0) or (0,π). It is known that while a small amount of Co substitution lead to SC, the same does not occur for Mn for any value of x. In this work, magnetic excitations in the iron arsenides ...

Semimetal-to-semiconductor transition and charge-density-wave suppression in $1T\ensuremath{-}{\mathrm{TiSe}}_{2\ensuremath{-}x}{\mathrm{S}}_{x}$ single crystals

Mottas, Marie-Laure ; Jaouen, Thomas ; Hildebrand, Baptiste ; Rumo, Maxime ; Vanini, Fabiano ; Razzoli, Ellia ; Giannini, E. ; Barreteau, C. ; Bowler, D. R. ; Monney, Claude ; Beck, Hans ; Aebi, Philipp

In: Physical Review B, 2019, vol. 99, no. 15, p. 155103

Time- and angle-resolved photoemission spectroscopy of solids in the extreme ultraviolet at 500 kHz repetition rate

Puppin, M. ; Deng, Y. ; Nicholson, Christopher W. ; Feldl, J. ; Schröter, N. B. M. ; Vita, H. ; Kirchmann, P. S. ; Monney, Claude ; Rettig, L. ; Wolf, M. ; Ernstorfer, R.

In: Review of Scientific Instruments, 2019, vol. 90, no. 2, p. 023104

Time- and angle-resolved photoemission spectroscopy (trARPES) employing a 500 kHz extreme-ultraviolet light source operating at 21.7 eV probe photon energy is reported. Based on a high-power ytterbium laser, optical parametric chirped pulse amplification, and ultraviolet-driven high-harmonic generation, the light source produces an isolated high-harmonic with 110 meV bandwidth and a flux of...

Coupled Cu and Mn charge and orbital orders in YBa₂Cu₃O₇/Nd 0.65 (Ca 1-y Sr y ) 0.35 MnO₃ multilayers

Perret, Edith ; Monney, Claude ; Johnston, S. ; Khmaladze, Jarji ; Lyzwa, Fryderyk ; Gaina, Roxana ; Dantz, M. ; Pelliciari, Jonathan ; Piamonteze, C. ; Mallett, B.P.P. ; Minola, M. ; Keimer, B. ; Schmitt, Thorsten ; Bernhard, Christian

In: Communications Physics, 2018, vol. 1, no. 1, p. 45

The observation of a charge density wave in the underdoped cuprate high Tc superconductors (Cu-CDW) raised a debate about its relationship with superconductivity. In bulk YBa2Cu3O7−δ the Cu-CDW is incipient and mainly pinned by defects. Nevertheless, a large magnetic field can induce a true long-range Cu- CDW order as it suppresses superconductivity. An enhanced Cu-CDW order was also ...

Inhibition of the photoinduced structural phase transition in the excitonic insulator ${\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}$

Mor, Selene ; Herzog, Marc ; Noack, Johannes ; Katayama, Naoyuki ; Nohara, Minoru ; Takagi, Hide ; Trunschke, Annette ; Mizokawa, Takashi ; Monney, Claude ; Stähler, Julia

In: Physical Review B, 2018, vol. 97, no. 11, p. 115154

Femtosecond time-resolved midinfrared reflectivity is used to investigate the electron and phonon dynamics occurring at the direct band gap of the excitonic insulator Ta2NiSe5 below the critical temperature of its structural phase transition. We find that the phonon dynamics show a strong coupling to the excitation of free carriers at the Γ point of the Brillouin zone. The optical response...

Robustness of the charge-ordered phases in ${\mathrm{IrTe}}_{2}$ against photoexcitation

Monney, Claude ; Schuler, A. ; Jaouen, T. ; Mottas, Marie-Laure ; Wolf, Thomas ; Merz, M. ; Muntwiler, Matthias ; Castiglioni, L. ; Aebi, Philipp ; Weber, F. ; Hengsberger, M.

In: Physical Review B, 2018, vol. 97, no. 7, p. 075110

We present a time-resolved angle-resolved photoelectron spectroscopy study of IrTe2, which undergoes two first-order structural and charge-ordered phase transitions on cooling below 270 K and below 180 K. The possibility of inducing a phase transition by photoexcitation with near-infrared femtosecond pulses is investigated in the charge-ordered phases. We observe changes of the spectral...

Ultrafast electronic band gap control in an excitonic insulator

Mor, Selene ; Herzog, Marc ; Golež, Denis ; Werner, Philipp ; Eckstein, Martin ; Katayama, Naoyuki ; Nohara, Minoru ; Takagi, Hide ; Mizokawa, Takashi ; Monney, Claude ; Stähler, Julia

In: Physical Review Letters, 2017, vol. 119, no. 8, p. 086401

We report on the nonequilibrium dynamics of the electronic structure of the layered semiconductor Ta2NiSe5 investigated by time- and angle-resolved photoelectron spectroscopy. We show that below the critical excitation density of FC=0.2 mJ cm−2, the band gap narrows transiently, while it is enhanced above FC. Hartree-Fock calculations reveal that this effect can be explained by the presence...