Université de Fribourg

Uniaxial strain-induced phase transition in the 2D topological semimetal IrTe2

Nicholson, Christopher W. ; Rumo, Maxime ; Pulkkinen, Aki ; Kremer, Geoffroy ; Salzmann, Björn ; Mottas, Marie-Laure ; Hildebrand, Baptiste ; Jaouen, Thomas ; Kim, Timur K. ; Mukherjee, Saumya ; Ma, KeYuan ; Muntwiler, Matthias ; von Rohr, Fabian O. ; Cacho, Cephise ; Monney, Claude

In: Communications Materials, 2021, vol. 2, no. 1, p. 25

Strain is ubiquitous in solid-state materials, but despite its fundamental importance and technological relevance, leveraging externally applied strain to gain control over material properties is still in its infancy. In particular, strain control over the diverse phase transitions and topological states in two-dimensional transition metal dichalcogenides remains an open challenge. Here, we...

Université de Fribourg

Unveiling the Semimetallic Nature of 1$T$-TiSe$_2$ by Doping its Charge Density Wave

Jaouen, Thomas ; Rumo, Maxime ; Hildebrand, Baptiste ; Mottas, Marie-Laure ; Nicholson, Christopher W. ; Kremer, Geoffroy ; Salzmann, Björn ; Vanini, Fabiano ; Barreteau, C. ; Giannini, E. ; Beck, Hans-Peter ; Aebi, Philipp ; Monney, Claude

The semimetallic or semiconducting nature of the transition metal dichalcogenide 1$T$-TiSe$_2$ remains under debate after many decades mainly due to the fluctuating nature of its 2 x 2 x 2 charge-density-wave (CDW) phase at room- temperature. In this letter, using angle-resolved photoemission spectroscopy, we unambiguously demonstrate that the 1$T$-TiSe$_2$ normal state is semimetallic with ...

Université de Fribourg

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...

Université de Fribourg

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...

Université de Fribourg

Local real-space view of the achiral $1T\text{\ensuremath{-}}{\mathrm{TiSe}}_{2}$ $2\times2\times2$ charge density wave

Hildebrand, Baptiste ; Jaouen, Thomas ; Mottas, Marie-Laure ; Monney, Gaël ; Barreteau, C. ; Giannini, E. ; Bowler, D. R. ; Aebi, Philipp

In: Physical Review Letters, 2018, vol. 120, no. 13, p. 136404

The transition metal dichalcogenide 1T−TiSe2-two-dimensional layered material undergoing a commensurate 2×2×2 charge density wave (CDW) transition with a weak periodic lattice distortion (PLD) below ≈200 K. Scanning tunneling microscopy (STM) combined with intentionally introduced interstitial Ti atoms allows us to go beyond the usual spatial resolution of STM and to intimately probe...

Université de Fribourg

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...

Université de Fribourg

Local resilience of the $1T\text{\ensuremath{-}}{\mathrm{TiSe}}_{2}$ charge density wave to Ti self-doping

Hildebrand, Baptiste ; Jaouen, Thomas ; Didiot, Clément ; Razzoli, Elia ; Monney, Gaël ; Mottas, Marie-Laure ; Vanini, Fabiano ; Barreteau, C. ; Ubaldini, A. ; Giannini, E. ; Berger, Helmuth ; Bowler, D. R. ; Aebi, Philipp

In: Physical Review B, 2017, vol. 95, no. 8, p. 081104

In Ti-intercalated self-doped 1T−TiSe2 crystals, the charge density wave (CDW) superstructure induces two nonequivalent sites for Ti dopants. Recently, it has been shown that increasing Ti doping dramatically influences the CDW by breaking it into phase-shifted domains. Here, we report scanning tunneling microscopy and spectroscopy experiments that reveal a dopant-site dependence of the CDW...

Université de Fribourg

Selective probing of hidden spin-polarized states in inversion-symmetric bulk ${\mathrm{MoS}}_{2}$

Razzoli, Elia ; Jaouen, Thomas ; Mottas, Marie-Laure ; Hildebrand, Baptiste ; Monney, Gaël ; Pisoni, A. ; Muff, S. ; Fanciulli, M. ; Plumb, N. C. ; Rogalev, V. A. ; Strocov, V. N. ; Mesot, Joël ; Shi, Ming ; Dil, J. H. ; Beck, Hans ; Aebi, Philipp

In: Physical Review Letters, 2017, vol. 118, no. 8, p. 086402

Spin- and angle-resolved photoemission spectroscopy is used to reveal that a large spin polarization is observable in the bulk centrosymmetric transition metal dichalcogenide MoS2. It is found that the measured spin polarization can be reversed by changing the handedness of incident circularly polarized light. Calculations based on a three-step model of photoemission show that the valley and...

Université de Fribourg

Short-range phase coherence and origin of the $1T-{\mathrm{TiSe}}_{2}$ charge density wave

Hildebrand, Baptiste ; Jaouen, Thomas ; Didiot, Clément ; Razzoli, Elia ; Monney, Gaël ; Mottas, Marie-Laure ; Ubaldini, A. ; Berger, Helmuth ; Barreteau, C. ; Beck, Hans ; Bowler, D. R. ; Aebi, Philipp

In: Physical Review B, 2016, vol. 93, no. 12, p. 125140

The impact of variable Ti self-doping on the 1T−TiSe2 charge density wave (CDW) is studied by scanning tunneling microscopy. Supported by density functional theory, we show that agglomeration of intercalated-Ti atoms acts as preferential nucleation centers for the CDW that breaks up in phase-shifted CDW domains whose size directly depends on the intercalated-Ti concentration and which are...