Anisotropic Particle-Hole Excitations in Black Phosphorus

Abstract

We report on the energy- and momentum-resolved optical response of black phosphorus (BP) in its bulk form. Along the armchair direction of the puckered layers, we find a highly dispersive mode that is strongly suppressed in the perpendicular (zigzag) direction. This mode emerges out of the single-particle continuum for finite values of momentum and is therefore interpreted as an exciton. We argue that this exciton, which has already been predicted theoretically for phosphorene-the monolayer form of BP-can be detected by conventional optical spectroscopy in the two-dimensional case and might pave the way for optoelectronic applications of this emerging material.

Electronic structure and thermoelectric transport of black phosphorus

“…This behavior is often seen in Kondo insulators, where local quantum fluctuations induce the FL low-energy coherence. Thus, in bulk BP, the transfer of spectral weight found in the FL semiconducting phase can be traced to a dynamical scattering process that leads to electron mass enhancement consistent with experimental observations [16]. Taken together, our results constitute a consistent, quantitative rationalization of basic one-particle responses of bulk BP and serve as a starting point to explore the orbital reconstruction upon electron and hole doping the parent compound; see our study below.…”

“…Interestingly, in these orbitals the UHBs close to 6 eV in the conduction band are more clearly resolved compared to the p z orbital. This can be taken as a fingerprint of asymmetric, orbital-selective Coulomb correlation effects in bulk BP which might be relevant to understanding anisotropic particle-hole excitations probed in optics [16]. While large transfer of spectral weight from lower to higher energies is obtained, the spectral line shape close to E F remains close to that found in LDA.…”

“…1. Due to its intrinsic semiconducting band gap [12][13][14] and peculiar electronic structure [15] it displays anisotropic particle-hole excitations [16], magnetoresistance [10], and thermal transport properties [4]. Moreover, the band gap of bulk BP is tunable by strain [3] and moderated pressures [17].…”

Electron-hole asymmetry in the electron-phonon coupling in top-gated phosphorene transistor

“…2 Recent photoluminescence measurements on the monolayer show the existence of anisotropic excitons emitting light, polarized along the armchair direction, with a relatively higher exciton binding energy of around 0.7-0.8 eV and a quasi particle gap of 2.2 eV. 5,6,14,15 For 2-D systems like graphene, electron-phonon coupling (EPC) plays a dominant role in the resistivity behaviour at high carrier densities. 16 For almost a decade, since the emergence of graphene, 17,18 Raman spectroscopy has scored over other techniques as an indispensable analytical tool for estimation of the number of layers in 2D materials like graphene and TMDs, [19][20][21][22][23] to characterize EPC in 2-D graphene [24][25][26] and evaluating thermal conductivity of graphene layers [27][28][29] among various other properties.…”

Optical third harmonic generation in black phosphorus

“…[52] and also by the dielectric function of bulk bP computed from EELS data in Ref. [53]. Based on these experimental reports and the above-mentioned arguments, we expect that the nonlinear response of bulk bP can be accurately characterized within the framework of the single-particle approximation.…”