Spectroscopic fingerprints of many-body renormalization in 1T−TiSe2

Abstract

We have employed high resolution angle resolved photoemission spectroscopy (ARPES) measurements to investigate many-body renormalizations of the single-particle excitations in 1T -TiSe2 . The energy distribution curves of the ARPES data reveal intrinsic peak-dip-hump feature, while the electronic dispersion derived from the momentum distribution curves of the data highlights, for the first time, multiple kink structures. These are canonical signatures of a coupling between the electronic degrees of freedom and some Bosonic mode in the system. We demonstrate this using a model calculation of the single-particle spectral function at the presence of an electron-Boson coupling. From the self-energy analysis of our ARPES data, we discern some of the critical energy scales of the involved Bosonic mode, which are ∼15 and 26 meV. Based on a comparison between these energies and the characteristic energy scales of our Raman scattering data, we identify these Bosonic modes as Raman active breathing (A1g) and shear (Eg) modes, respectively. Direct observation of the band-renormalization due to electron-phonon coupling increases the possibility that electron-phonon interactions are central to the collective quantum states such as Charge density wave (CDW) and superconductivity in the compounds based on 1T -TiSe2 .

Metal-to-insulator transition in Pt-doped TiSe$_2$ driven by emergent network of narrow transport channels

“…The other question is how unique is the Luttinger liquid mechanism of MIT? Remarkably, a similar mechanism of Luttinger transport was recently reported in a very different system: Power laws have been observed in the mass transport through a network of dislocations in solid 4 He generated by a pressure difference 35 . This suggests a more ubiquitous occurrence of the network of Lut-tinger liquid channel transport.…”

“…Fig. 3 shows the energy-momentum intensity maps (EMIMs) 4 around the L point for x = 0.1 and x = 0, respectively. The EMIM depicts the ARPES intensity as a function of one of the in-plane momentum components and electronic energy ω referenced to the chemical potential µ, while keeping the other orthogonal in-plane momentum component fixed.…”

Metal-to-insulator transition in Pt-doped TiSe2 driven by emergent network of narrow transport channels

“…To gain insight into the MIT in 1T-Pt x Ti 1−x Se 2 , we study the evolution of the single-particle spectral function of the doped single crystals from the metallic to the insulating regime using ARPES. Figure 3a, d show the energy-momentum intensity maps (EMIMs) 15 around the L point for x = 0.1 and x = 0, respectively. The EMIM depicts the ARPES intensity as a function of one of the in-plane momentum components and electronic energy ω referenced to the chemical potential μ, while keeping the other orthogonal in-plane momentum component fixed.…”

Electron-Exciton Coupling in 1T-TiSe2 Bilayer

“…S13). q 1 q 2 q 2 q 3 q 3 It is well known that the coupling of electrons to a bosonic mode, such as phonons or excitons, can lead to the renormalization of the electronic energy band, [33][34][35] we therefore explore such a picture of electron-boson coupling based on a phenomenological model given by…”

“…The experimentally determined extra state bottom at ∼ −230 mV and CBM at ∼ −60 mV gives the energy of 𝛺0 to be ∼ 170 meV, much larger than the phonon energies of <∼ 30 meV as reported in 1T-TiSe2. [15,20,23,35] The formation of an exciton, a bound state of an electronhole excitation, is signified by the divergence of the renormalized electron-hole susceptibility. [34,37,38] Thus, the exciton mode should fall into the gap between the Fermi level and VBM.…”