Surface scattering velocities in III-nitride quantum well laser structures via the emission of hybrid phonons

We have theoretically and numerically studied nitride-based quantum well (QW) laser structures. More specifically, we have used a QW made with III-nitride where the width of the barrier region is large relative to the electron mean free path, and we have calculated the electron surface capture velocities by considering an electron flux which is captured into the well region. The process is assisted by the emission of the longitudinal optical phonons as predicted by the hybrid (HB) model. The results of surface capture velocities via the emission of HB phonons are compared to the emission of the dielectric continuum phonons (Zakhleniuk et al 1999 Phys. Status Solidi a 176 79). Our investigation shows that the two different phonon models predict almost the same results for the non-retarded limit. Furthermore, the surface capture velocities strongly depend on the size of the structure and the heterostructure materials. Lastly, a comparison to the recent experimental values shows that our model could accurately describe the experimentally measured parameters of the quantum capture processes

Electron Scattering and Hybrid Phonons in Low Dimensional Laser Structures made with GaAs/AlxGa1-xAs

We theoretically and numerically present the hybrid phonon modes for the double heterostructure GaAs/AlxGa1-xAs and their interactions with electrons. More specifically, we have calculated the electron capture within a symmetric quantum well via the emission of hybrid phonons. Our investigation shows that the capture rates via the hybrid phonons are matched to the rates predicted by the dielectric continuum (DC) model and the concentration of aluminium which is an important parameter for controlling the electron capture process in light emitting diodes (LED).Comment: 11 page

Suppression of electron relaxation and dephasing rates in quantum dots caused by external magnetic fields

An external magnetic field has been applied in laterally coupled dots (QDs) and we have studied the QD properties related to charge decoherence. The significance of the applied magnetic field to the suppression of electron-phonon relaxation and dephasing rates has been explored. The coupled QDs have been studied by varing the magnetic field and the interdot distance as other system parameters. Our numerical results show that the electron scattering rates are strongly dependent on the applied external magnetic field and the details of the double QD configuration.Comment: 13 pages, 6 figure

Magnetic Skyrmions in FePt Square-Based Nanoparticles Around Room-Temperature

Magnetic skyrmions formed around room-temperature in square-based parallelepiped magnetic nanoparticles with perpendicular magnetocrystalline anisotropy similar to that of partially chemically ordered FePt were studied during the magnetization reversal using micromagnetic simulations. Finite Differences (FD) discretizations were used for the solution of the Landau-Lifshitz-Gilbert equation. Magnetic configurations exhibiting N\'eel chiral stripe and N\'eel skyrmionic formations were detected. The magnetic skyrmions can be created in different systems generated by the variation of external field, side length and width of the squared-based parallelepiped magnetic nanoparticles. Micromagnetic configurations revealed a variety of states which include skyrmionic textures with one distinct skyrmion formed and being stable for a range of external fields around room-temperature. The size of the formed N\'eel skyrmion is calculated as a function of the external field, temperature, magnetocrystalline anisotropy and nanoparticle's geometrical characteristic lengths which can be adjusted to produce N\'eel type skyrmions on demand having diameters down to 12 nm. The micromagnetic simulations revealed that stable skyrmions at the temperature range 270K-330K can be created for FePt magnetic nanoparticle systems lacking of chiral interactions such as Dzyaloshinsky-Moriya, providing new perspectives in the new magnetic writing era.Comment: 11 pages,12 Figures, research articl

Whitman and Nietzsche: A Comparative Study of Their Thought

This volume will be a great aid to students and scholars alike in American literature, American thought, the history of ideas, and comparative literature. Stavrou draws from the entire bodies of work by Whitman and Nietzsche to explore the parallels in the authors' conceptions of paradox, the totality of life, and solitude among other themes in this exploration of the underlying philosophical similarities of these two great writers of the nineteenth century

Psychosocial Effects of Iron Chelation on Thalassemia Patients

Introduction: Hemodialysis is a serious consequence of transfusions in the treatment of b-thalassemia major. Iron deficiency burdens the psychology of patients and due to the complexity and long process can be abandoned as a treatment. Aim: To study the perceptions and limitations experienced by patients undergoing iron deficiency, as well as the psychological effects. Methodology: The study was conducted in the Mediterranean Anemia Unit of Evangelismos Hospital. The study included patients with b-Mediterranean anemia, who were informed about the purpose of the study and gave signed consent. The research is a qualitative study with semi-structured interviews. Results: The analysis of 70 patient interviews (32 men - 38 women) showed that the majority of patients (54 participants) are regular in iron deficiency therapy, as they find that it improves survival expectancy. Six participants are not regular, as they feel that it limits them significantly, while the rest try to be regular, as they recognize its benefits. 41 participants have a positive attitude towards treatment, of which 13 state that treatment improves their quality of life, while the remaining 29 have a negative attitude towards treatment. Regarding the existence of a supportive environment, 47 participants state that they have a supportive family environment, while 11 participants state that they hide from the family environment and 12 participants have experienced or are still experiencing the stigma due to the disease. Conclusions: It is important to facilitate patients with iron deficiency treatments, which do not limit their daily life. Also, the psychological support of patients with thalassemia is important, so that they overcome the obstacles of the disease and live a life with fewer obstacles