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...
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In: Physical Review B, 2019, vol. 99, no. 15, p. 155103
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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...
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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...
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In: Physical Review B, 2015, vol. 92, no. 8, p. 081111
We show that double-layer graphene (DLG), where an external potential induces a charge imbalance between n- and p-type layers, is a promising candidate to realize an exciton condensate in equilibrium. To prove this phenomenon experimentally, we suggest coupling two DLG systems, separated by a thin insulating barrier, and measuring the excitonic Josephson effect. For this purpose we calculate the...
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In: Physical Review Letters, 2015, vol. 114, no. 8, p. 086402
Several experiments have been performed on 1T−TiSe2 in order to identify whether the electronic structure is semimetallic or semiconducting without reaching a consensus. In this Letter, we theoretically study the impact of electron-hole and electron-phonon correlations on the bare semimetallic and semiconducting electronic structure. The resulting electron spectral functions provide a...
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In: Physical Review B, 2014, vol. 90, no. 19, p. 195118
The influence of phonons on the formation of the excitonic insulator has hardly been analyzed so far. Recent experiments on Ta2NiSe5,1T−TiSe2, and TmSe0.45Te0.55, being candidates for realizing the excitonic-insulator state, suggest, however, that the underlying lattice plays a significant role. Employing the Kadanoff-Baym approach we address this issue theoretically. We show that owing to the...
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In: Physical Review B, 2013, vol. 88, no. 7, p. 075138
We address the question of the origin of the recently discovered chiral property of the charge-density-wave phase in 1T-TiSe₂, which so far lacks a microscopic understanding. We argue that the lattice degrees of freedom seem to be crucial for this novel phenomenon. We motivate a theoretical model that takes into account one valence and three conduction bands, a strongly screened Coulomb...
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In: Physical Review B - Condensed Matter and Materials Physics, 2012, vol. 85, no. 23, p. 235150
To address the fluctuation regime above the critical temperature of the charge-density-wave phase of 1T-TiSe₂, we perform calculations using the Bethe-Salpeter equation for treating strong electron-hole correlations. Calculated photoemission intensity maps are in good agreement with the measured ones and provide a deeper understanding of the phase transition in terms of an electronic...
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In: Physical Review Letters, 2012, vol. 109, p. 047401
In high-resolution resonant inelastic x-ray scattering at the Ti L edge of the charge-density-wave system 1T-TiSe₂, we observe sharp low energy loss peaks from electron-hole pair excitations developing at low temperature. These excitations are strongly dispersing as a function of the transferred momentum of light. We show that the unoccupied bands close to the Fermi level can effectively be...
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