Thermal and Magnetic Properties of Exciton in TMD_WS2, WSe2 Monola رسالة دكتوراة

Abstract

In this thesis, an exciton present in a sheet of TMD material (WS2 and WSe2) was highlighted to conduct studies covering different properties. We solved the Schrödinger equation by shifted 1/N expansion method to obtain the eigen energy for the exciton present in the TMD material. We talked about energy spectra, as we clarified the energy state values that were obtained mathematically using the 1/N-shift expansion method and compared them with other energy state values that were obtained numerically. After that, we highlighted the ground state energy (average energy) as a function of temperature at different values of the magnetic field (between 0 to 94T for WSe2 and 0 to 60.16 for WS2). The thermal and magnetic properties of the exciton contained in a sheet of TMD material were studied based on different values of the magnetic field at different temperatures. Starting with the thermal properties, we talked about the heat capacity, and entropy. In addition, we have displayed the dependence of magnetization and magnetic susceptibility of exciton in QD with various physical parameters (B, T). In addition to the physical description of the effect of each system parameter on the energy spectra, we calculated the density of state of the system. Thermomagnetic properties were also studied under the name Magneto Caloric Effect (MCE) of an exciton found in TMD Material, which represents the difference in randomness (entropy) of the system at two different values of a magnetic field affecting this system. The latest study conducted in this thesis, relates to the magnetism of an exciton found within the TMD material. By knowing the ability of these materials to respond to the applied magnetic field, this was done through studying the so-called diamagnetic shift (σ). Better yet, the results we obtained through 1/N expansion method were matched with results in other important previous studies on the theoretical and experimental leve