Journal of Physical Studies 12(4), Article 4604 [6 pages] (2008) DOI: https://doi.org/10.30970/jps.12.4604 CONSEQUENCES OF LOW-ENERGY NON-PARABOLICITY OF THE DISPERSION LAWS FOR PHYSICAL PARAMETERS AND MANIFESTATION OF NEW EFFECTS IN STRONGLY ANISOTROPIC CRYSTALS D. M. Bercha{1,2}, L. Yu. Kharkhalis{1}, M. Sznajder{2}, K. Z. Rushchanskii{1}, I. V. Slipukhina{1} {1}Institute of Physics and Chemistry of Solid State, Uzhgorod National University, Uzhgorod, Ukraine {2}Institute of Physics, University of Rzeszów, Rejtana 16a, 35-310 Rzeszów, Poland bercha@univ.rzeszow.pl, lkharkhalis@gmail.com

The effects of low-energy non-parabolicity are studied in the anomalous behavior of the effective mass anisotropy in a hexagonal $β$-InSe and in the anomaly of the optical absorption edge of an orthorhombic In$_4$Se$_3$ crystal. The influence of shear strains on the dispersion laws of electrons and holes in the vicinity of band gap of the In$_4$Se$_3$ crystal is studied. In the framework of two-interacting-band $\mathbf{k \cdot p}$-approach it is established that the shear deformations $ε_{xz}$ shift the extrema of $E({\bf k})$ into the close vicinity of $Γ$-point leading to the low-energy non-parabolicity in $k_z$-direction. The changes which appear due to accounting for the shear deformations allow one to understand the nature of the \emph{ab initio} observed transformations of low-energy non-parabolicity induced by an impurity intercalated into the van der Waals space of the In$_4$Se$_3$ crystal. For the latter crystal possibilities of a new-type quasiparticles formation caused by low-energy non-parabolicity are analyzed.

PACS number(s): 61.72.Bb, 71.15.Mb, 71.20.-b, 71.20.Nr, 78.20.Ci

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