Unveiling the orbital texture of 1T-TiTe2 using intrinsic linear dichroism in multidimensional photoemission spectroscopy

Samuel Beaulieu,Martin Wolf,Michael Schüler,Ján Minár,Shuo Dong,Ralph Ernstorfer,Friedrich Reinert,Laurenz Rettig,Julian Maklar,Tommaso Pincelli,Alexander Neef,Jakub Schusser

doi:10.1038/s41535-021-00398-3

Abstract

The momentum-dependent orbital character in crystalline solids, referred to as orbital texture, is of capital importance in the emergence of symmetry-broken collective phases, such as charge density waves as well as superconducting and topological states of matter. By performing extreme ultraviolet multidimensional angle-resolved photoemission spectroscopy for two different crystal orientations linked to each other by mirror symmetry, we isolate and identify the role of orbital texture in photoemission from the transition metal dichalcogenide 1T-TiTe2. By comparing our experimental results with theoretical calculations based on both a quantitative one-step model of photoemission and an intuitive tight-binding model, we unambiguously demonstrate the link between the momentum-dependent orbital orientation and the emergence of strong intrinsic linear dichroism in the photoelectron angular distributions. Our results represent an important step towards going beyond band structure (eigenvalues) mapping and learning about electronic wavefunction and orbital texture of solids by exploiting matrix element effects in photoemission spectroscopy.

Highlights

Angle-resolved photoemission spectroscopy (ARPES) is the most direct experimental technique to measure the momentumresolved electronic eigenvalues of crystalline solids[1,2]
We have extended the recently introduced differential measurement methodology in multidimensional photoemission spectroscopy to investigate the role of orbital texture in photoemission from a semimetallic layered transition metal dichalcogenide (TMDC) (1T-TiTe2)
We introduced the intrinsic linear dichroism in photoelectron angular distributions—a generalized version of TRDAD, in samples featuring inversion symmetry

Summary

Introduction

Angle-resolved photoemission spectroscopy (ARPES) is the most direct experimental technique to measure the momentumresolved electronic eigenvalues (energy bands) of crystalline solids[1,2]. The technique is based on the photoelectric effect[3,4], in which electrons inside solids absorb a photon with energy larger than the work function and escape into the vacuum. A key aspect of ARPES is that the energy (E) and momentum (k)-resolved photoemission signal is proportional to the single-particle spectral function A(k, E)[5], a fundamental quantity containing key information about many-body interactions inside solids. Because of its semimetallic 2D nature and its speculated textbook FermiLiquid behavior, the layered transition metal dichalcogenide (TMDC) 1T-TiTe2 was the central material around the debate on directly linking the spectral function and the ARPES lineshape[7,8,9,10]. 1T-TiTe2 served as a benchmark material to demonstrate the signatures of many-body effects in ARPES lineshape[11], the possibility to retrieve the photohole lifetime[12], as well as the potential to dissect the role of the different quasiparticle scattering processes from ARPES measurements[10]

Methods

Results

Conclusion