Electronic Polarizability as the Fundamental Variable in the Dielectric Properties of Two-Dimensional Materials

Abstract

The dielectric constant, which defines the polarization of the media, is a key quantity in condensed matter. It determines several electronic and optoelectronic properties important for a plethora of modern technologies from computer memory to field effect transistors and communication circuits. Moreover, the importance of the dielectric constant in describing electromagnetic interactions through screening plays a critical role in understanding fundamental molecular interactions. Here we show that despite its fundamental transcendence, the dielectric constant does not define unequivocally the dielectric properties of two-dimensional (2D) materials due to the locality of their electrostatic screening. Instead, the electronic polarizability correctly captures the dielectric nature of a 2D material which is united to other physical quantities in an atomically thin layer. We reveal a long-sought universal formalism where electronic, geometrical and dielectric properties are intrinsically correlated through the polarizability opening the door to probe quantities yet not directly measurable including the real covalent thickness of a layer. We unify the concept of dielectric properties in any material dimension finding a global dielectric anisotropy index defining their controllability through dimensionality.

Changing the Electronic Polarizability of Monolayer MoS2 by Perylene‐Based Seeding Promoters

“…[ 23 ] In 2D materials, the confined nature of the atomically thin layer poses serious concerns on the physical definition of the dielectric constant, opening new room for the interpretation of the calculated capacitances, and thus of the screening potential efficiency, as a marker for the local polarizability of the electronic distribution and the presence of free charges trapped in the samples. [ 20–22,24 ]…”

Ab Initio Positioning of the Valence and Conduction Bands of Bulk Photocatalysts: Proposition of Absolute Reference Energy

“…Essentially, the limitation of the dielectric screening or vacuum width dependent dielectric function in slab calculation A c c e p t e d M a n u s c r i p t forbids us optimizing the Fock-exchange for these compounds from dielectric depend self-consistent runs from plane-wave based tools. 39 Thus linear variations with least-square fitting would be another safe approach. However, we must mention here that the choice of the Hartree-Fock exchange is thus, not purely from the empirical choice from the standard hybrid functional, but more likely semi-empirical, as referred to the known experimental flat-band data.…”

Remote free-carrier screening to boost the mobility of Fröhlich-limited two-dimensional semiconductors

“…In the 2D framework, the long-wavelength Fröhlich electron-phonon coupling (see Appendix A 3) can be thought of as the ratio of a parameter depending on BECs and mildly on momentum, and the dielectric function (q), which accounts for both the environment and the material containing the electrons involved. The dielectric function in the longwavelength limit (q → 0) can be modeled as 1 + αq for a 2D material in vacuum, where α is the polarizability of the 2D layer [34][35][36][37], but the present work relies on a more detailed and realistic model. One general behavior is that in 2D the dielectric function is dominated by the response of the environment for q → 0 and by that of the 2D material for q → ∞.…”