Optical Response of a screw dislocated GaAs Quantum Wire: Temperature and Pressure Effects

TL;DR

This study analyzes how screw dislocations, temperature, pressure, and magnetic fields influence the optical properties of GaAs quantum wires, revealing shifts in absorption peaks and refractive index changes.

Contribution

It provides exact solutions for the optical response of dislocated GaAs quantum wires considering combined effects of temperature, pressure, and magnetic field, highlighting dislocation-induced asymmetries.

Findings

Dislocation parameter causes redshift in m=0→+1 transition and blueshift in m=0→−1 transition.

Temperature increases shift resonances to higher energies and amplify peaks.

Hydrostatic pressure causes redshift and reduces peak intensity for both transitions.

Abstract

We investigate the influence of a screw dislocation, characterized by the dislocation parameter, on the optical response of a parabolic GaAs cylindrical quantum wire under the combined effects of temperature, hydrostatic pressure, and the axial magnetic field. Using a torsion-modified metric together with pressure- and temperature-dependent material properties, namely the effective mass and dielectric permittivity, we obtain exact solutions of the Schr\"odinger equation in terms of Whittaker functions. The screw dislocation introduces a \(k_z\)-dependent coupling that breaks the symmetry between the angular momentum states \(m\) and \(-m\) and modifies the centrifugal term in the effective potential. Based on the resulting eigenstates, we evaluate the linear and third-order nonlinear optical absorption coefficients, as well as the corresponding refractive index changes, for the dipole-allowed transitions \(m = 0 \to +1\) and \(m = 0 \to -1\). Our results show that increasing the dislocation parameter produces a pronounced redshift and suppresses the resonance amplitude for the \(m = 0 \to +1\) transition, whereas the \(m = 0 \to -1\) transition exhibits a blueshift accompanied by peak enhancement. We further find that increasing temperature shifts the resonances toward higher photon energies and enhances their amplitudes, while hydrostatic pressure causes a redshift and reduces the peak intensity for both transitions. In addition, the magnetic field strengthens the optical response and induces a blueshift for the \(m = 0 \to +1\) transition, whereas the opposite behavior is obtained for the \(m = 0 \to -1\) transition. We have also examined the behavior of the refractive index changes, which exhibit analogous asymmetric dependence on the dislocation parameter.