🔹Title: Ab initio simulations for electronic properties and structural instabilities in condensed matter
🔹Speaker: Dr. Marco Campetella (University of Siena)
🔹Abstract: Transition metal dichalcogenides (TMDs) display a rich variety of instabilities such as spin and charge orders, Ising superconductivity, and topological properties. Their physical properties can be controlled by doping in electric double-layer field-effect transistors (FET). However, for the case of single layer NbSe2, FET doping is limited to ≈1 × 1014 cm−2 [1,2]. In this talk I will show, by presenting angle-resolved photoemission spectroscopy, scanning tunneling microscopy, quasiparticle interference measurements, and first-principles calculations, that a misfit compound formed by sandwiching NbSe2 and LaSe layers behaves as a NbSe2 single layer with a rigid doping of 0.55–0.6 electrons per Nb atom or ≈6 × 1014 cm−2 [3].
In the second part of my talk, I will present recent results on CuTe. This compound, called vulcanite, is one of the prototypical quasi1D systems that can be viewed as a quasi-1D CDW system with Peierls-like distortion which undergoes a CDW transition at TCDW = 335 K [4,5]. In order to provide additional theoretical insights into the CDW phase transition properties, we have studied the anharmonic phonon spectra of bulk CuTe within the stochastic self-consistent harmonic approximation (SSCHA) [6]. In particular, by using the exchange interaction via semi- local functionals in the force calculation, we have determined the nature and the temperature of the CDW transition [7].
