Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 74: Frontiers of electronic structure theory: 2D TMDC and excitonic effects

HL 74.2: Talk

Thursday, March 19, 2015, 11:00–11:15, MA 004

Screening of the Coulomb interaction in two-dimensional semiconductors: The case of transition metal dichalcogenides — •Ersoy Sasioglu, Christoph Friedrich, and Stefan Blügel — Peter Grünberg Institut and Institute forAdvanced Simulation, Forschungszentrum Jülich and JARA, 52425Jülich, Germany

Experimentally determined large exciton binding energies and nonhydrogenic Rydberg series in monolayer transition metal (TM) dichalcogenides indicate a long-range behavior of the Coulomb interaction. By means of first-principles calculations in conjunction with the random-phase approximation [1,2] within the FLAPW method [3] we study screening of the Coulomb interaction in two-dimensional semiconducting TM dichalcogenides MX₂ (M=Cr, Mo, W; X=S, Se). We show that the screening in these systems deviates substantially from the bulk behavior, i.e., the short-range interaction is strongly screened, while the long-range interaction is anti-screened. This unconventional screening reduces the gradient of the Coulomb interaction giving rise to weak correlation effects, which explains the experimentally observed large exciton binding energies as well as the success of the one-particle density functional theory in the description of the electronic structure of these systems. This work has been supported in part by DFG-FOR-1346.
C. Friedrich et al., Phys. Rev. B. 81, 125102 (2010).
E. Şaşioğlu et al., Phys. Rev. B 83, 121101(R) (2011).
www.flapw.de