mohammad hadi Ahmadi
@liau.ac.ir
Physics, Faculty of Engineering
Lahijan Branch, Islamic Azad University
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Mahboobeh Ahmadi, Mehdi Sharif, Mehdi Sahami, and Amir Ramezannezhad
Springer Science and Business Media LLC
Ali Abdolahzadeh Ziabari, S.J. Mousavi, and M.H. Ahmadi
Elsevier BV
Abstract The electronic and optical properties of undoped and Ni–doped ZnO thin films with nanometer scale have been studied in the wurtzite phase, by first–principle approach. Density functional theory has been employed to calculate the fundamental properties of the films using full–potential linearized augmented plane–wave method. Ni doping was found to reduce the bandgap value of the material. Additionally, DOS effective mass of the electrons was evaluated. It was revealed that the effective mass of the electrons at the bottom of conduction band increased with Ni doping. Decrease of reflectance for thin films with nanometer scale in the UV–vis region was observed. The substitution by Ni decreased the intensity of the peaks, and a red shift was observed in the absorption peak. Moreover, the static dielectric constant, and static refractive index decreased with Ni content. Energy loss function of the modeled compounds was also evaluated. All calculated parameters were compared with the available experimental and other theoretical results.
S. Hamid Mehdipour and M.H. Ahmadi
Elsevier BV
Abstract In this paper, we explore the final stages of the black hole evaporation for Hayward solutions. Our results show that the behavior of Hawking's radiation changes considerably at the small radii regime such that the black hole does not evaporate completely and a stable remnant is left. We show that stability conditions hold for the Hayward solutions found in the Einstein gravity coupled with nonlinear electrodynamics. We analyze the effect that an inspired model of the noncommutativity of spacetime can have on the thermodynamics of Hayward spacetimes. This has been done by applying the noncommutative effects to the non-rotating and rotating Hayward black holes. In this setup, all point structures get replaced by smeared distributions owing to this inspired approach. The noncommutative effects result in a colder black hole in the small radii regime as Hayward's free parameter g increases. As well as the effects of noncommutativity and the rotation factor, the configuration of the remnant can be substantially affected by the parameter g. However, in the rotating solution it is not so sensitive to g with respect to the non-rotating case. As a consequence, Hayward's parameter, the noncommutativity and the rotation may raise the minimum value of energy for the possible formation of black holes in TeV-scale collisions. This observation can be used as a potential explanation for the absence of black holes in the current energy scales produced at particle colliders. However, it is also found that if extra dimensions do exist, then the possibility of the black hole production at energy scales accessible at the LHC for large numbers of extra dimensions will be larger.
S. Hamid Mehdipour and M. H. Ahmadi
Springer Science and Business Media LLC
We derive the mass term of the Bardeen metric in the presence of a noncommutative geometry induced minimal length. In this setup, the proposal of a stable black hole remnant as a candidate to store information is confirmed. We consider the possibility of having an extremal configuration with one degenerate event horizon and compare different sizes of black hole remnants. As a result, once the magnetic charge g$g$ of the noncommutative Bardeen solution becomes larger, both the minimal nonzero mass M0$M_{0}$ and the minimal nonzero horizon radius r0$r_{0}$ get larger. This means, subsequently, under the condition of an adequate amount of g$g$, the three parameters g$g$, M0$M_{0}$, and r0$r_{0}$ are in a connection with each other linearly. According to our results, a noncommutative Bardeen black hole is colder than the noncommutative Schwarzschild black hole and its remnant is bigger, so the minimum required energy for the formation of such a black hole at particle colliders will be larger. We also find a closely similar result for the Hayward solution.
M. Zakeri and M. Ahmadi
Elsevier BV