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- ItemMAGNETOCALORIC EFFECT AND ELECTRONIC PROPERTIES OF DOPED INSB - DOUBLE QUANTUM WIRE IN THE PRESENCE OF EM-FIELDS AND SPIN- ORBIT TERM(An-Najah National University, 2025-07-09) Ali, Mahmoud M.This study provides a comprehensive theoretical analysis of the electronic, magnetic, and thermodynamic properties of a double quantum wire (DQW) system made of Indium Antimonide (InSb), a material known for its high electron mobility and strong spin-orbit coupling. The study investigates the effect of the structural parameters of the confining potential, Rashba spin-orbit, external electric and magnetic fields, and impurity potential on the electronic, magnetic, and thermodynamic properties. We solve the Hamiltonian by using the exact diagonalization method, and then we compute the energy spectra, probability density distributions, local density of states (LDOS), magnetization, magnetic susceptibility, entropy, and magnetocaloric effect (MCE) for the double quantum wire system. Our numerical results show that the presence of the dopant potential changes the electronic structure, causing energy level shifts and breaking the symmetry between the two quantum wires. The impurity causes selective energy shifts, so that one wire undergoes large spectral changes while the other wire remains largely unchanged. Furthermore, the energy spectra and the probability density distributions analysis indicates that the quantized energy levels strongly depend on the structural parameters of the confining potential. The observed energy splitting and redistribution of probability density shows that the external fields provide a mechanism for controlling electronic properties for the system. Additionally, The effect of Rashba SOC and magnetic field variations on LDOS and spin-split state formation is explained. The influence of temperature, SOC strength, and electric field on the magnetic properties is analyzed, focusing on the transition from diamagnetic to paramagnetic behavior. The interplay between quantum and thermal effects is discussed. Our results highlight the critical role of spin-orbit coupling and external fields in controlling the magnetic responses. The MCE is studied by calculating entropy change and the refrigerant capacity (RC). We found that the refrigerant capacity (RC) increases nonlinearly with the Rashba spin-orbit coupling (SOC) strength. It is further enhanced when the impurity is placed at a specific position and when the external electric field is increased up to a certain value. These findings offer valuable insights for optimizing magnetocaloric materials for advanced technologies.
- ItemSTRUCTURAL, ELECTRONIC, MAGNETIC, AND ELASTIC PROPERTIES OF THE FULL-HEUSLER COMPOUNDS: CO2MNSI, CO2MNGE USING FP-LAPW METHOD(An-Najah National University, 2025-02-13) Hasan, DuaaThe Structural, electronic, magnetic, and elastic properties for both normal and inverse full-Heusler compounds Co2MnSi and Co2MnGe were investigated by using full potential linearized augmented plane wave (FP-LAPW) method, within density functional theory (DFT) that implemented in WEIN2k package. The generalized gradient approximation (GGA) has been used to compute the structural properties such as lattice parameter (a), bulk modulus (B), it’s first pressure derivative (B') and minimum energy (E0). Moreover, electronic,magnetic and elastic properties were found using GGA. In addition to GGA, modified Becke-Johnson Potential (mBJ) was used to enhance the band structure (BS). According to the density of states (DOS) and BS, both normal Co2MnSi and Co2MnGe compounds have half-metallic behavior, while invers Co2MnSi and Co2MnGe compounds are metallic. both normal and inverse Co2MnSi and Co2MnGe compounds are ferromagnetic materials. The normal Co2MnSi and Co2MnGe compounds and inverse Co2MnSi are mechanically stable, whereas inverse Co2MnGe compound is mechanically unstable. According to anisotropic factor (A), normal and inverse Heusler compounds Co2MnSi and normal Heusler compound Co2MnGe are elastic anisotropy. Pugh ratio (B/S) indicates that both normal and inverse Heusler compounds Co2MnSi, and normal Heusler compound Co2MnGe are ductile. According to Poisson’s ratio (ν) normal and inverse Heusler compounds Co2MnSi and normal Heusler compound Co2MnGe have ionic bonds.
- ItemSTUDY THE MAGNETOCALORIC EFFECT IN DILUTED MAGNETIC MANGANESE DOPED CADMIUM TELLURIDE (CD1-XMNXTE) QUANTUM WIRE(An-Najah National University, 2025-02-04) Shendi, AsadThis thesis presents a study for the Magnetocaloric effect of Cd1-xMnxTe magnetic nanomaterial. The Hamiltonian for an electron confined in a quantum wire, in the presence of an external magnetic field, and Rashba spin orbit interaction term had been solved. The obtained energy dispersion relation had been used to calculate: electronic structure and display Landau levels and density of states for different physical Hamiltonian parameters. The density of state function shows a significant dependence on spin, Rashba, exchange effect and magnetic field. We have computed the partition function, which is an essential step to calculate the magnetic and thermal quantities for QWW. We have shown dependence of magnetic properties like Magnetization and magnetic Susceptibility as function of magnetic field strength quantum wire radius, exchange and Rashba strength parameters. The computed results show that the material can display a phase transition between Paramagnetic and Diamagnetic types. We observed an oscillatory behavior in magnetic Susceptibility curve as a function of magnetic field calculated for different values of Rashba term quantum wire radius and magnetic exchange effect. This oscillating behavior is a result of Landau levels crossing in the quantum wire energy spectra. The behavior of the thermal properties like heat capacity and entropy have been investigated. This work includes a comprehensive study of magnetocaloric effect for this material at nanoscale. The obtained results for magnetocaloric effect reveal that the QWW made from Cd1-xMnxTe show an interesting MCE behavior at low temperature scale below 70K. QWW can absorb or release heat by switching the magnetic field on and off. The cooling/heating MCE process can be controlled by adjusting the physical parameters, like Rashba term, quantum wire radius, exchange term and magnetic field. These findings make our study attractive, and thus the selected magnetic wire material, good candidate for several future technological device applications for this type of magnetic nano material.
- ItemSTRUCTURAL, ELECTRONIC, MAGNETIC, AND ELASTIC PROPERTIES OF THE FULL-HEUSLER COMPOUNDS: FE2MNIN, AU2MNIN USING FP-LAPW METHOD.(An-Najah National University, 2024-10-01) Salma, BraikThe WIEN2k software package was employed to investigate the structural, electronic, magnetic, and elastic characteristics of Fe2MnIn and Au2MnIn full Heusler alloys. This analysis utilized the full Potential linearized augmented plane wave (FP-LAPW) method, which is rooted in density functional theory (DFT). The equilibrium structural parameters were deduced through the implementation of the generalized gradient approximation (GGA) for the exchange-correlation potential (εxc). Additionally, for enhanced numerical accuracy in calculating band gap energies, the modified Becke-Johnson (mBJ) potential was incorporated. The magnetic property calculations show that normal and inverse Fe2MnIn and Au2MnIn alloys are ferromagnetic. Furthermore, normal Fe2MnIn and inverse Au2MnIn are mechanically unstable, while normal Au2MnIn and inverse Fe2MnIn are mechanically stable, and both have a ductile nature with ionic bonds.
- ItemINVESTIGATION OF ELECTRICAL, OPTICAL AND MORPHOLOGICAL PROPERTIES OF SILVER NANOPARTICLES (Ag NPs) SYNTHESIZED BY MICROWAVE-ASSISTED (MW) SYNTHESIS METHOD(An-Najah National University, 2025-01-29) Habbash, ShahdNanoparticles (NPs) are very small-sized particles with a diameter ranging between 1 to 100 nm. Metallic nanoparticles take a huge place in recent researches because of its importance in different fields; electrical, optical, industrial and more. Among the known metals, silver (Ag) is the most especial one due to its physical and chemical properties. Several methods were used to prepare silver nanoparticles. The microwave-assisted synthesis method (MW) is the easiest way in which the Ag NPs can be synthesized in a very short time (some seconds), with high yield and controlled synthesis conditions. In this study, the Ag NPs were successfully prepared using the MW method. In the preparation process we used the precursor Silver Nitrate (AgNO3), with Ethylene Glycol as a reducing agent and polyvinylpyrrolid (PVP) as a stabilizing agent. The synthesis conditions were controlled during the preparation method. These conditions are the power of the microwave (Medium-Low, ML, Medium, M, Medium-High, MH, and High, H), the microwave heating time (30s and 90s) and the ratio between the precursor to stabilizing agent, AgNO3: PVP (1:1/2,1:1,1:2,1:3). The prepared samples were characterized using the ultra-violet visible absorption spectroscope (UV-vis). It is clear that both times can be used successfully to prepare Ag NPs, this is obtained from the peak of surface-plasmon resonance band (SPR) which exist in the correct region (400-450) nm. The atomic force microscope (AFM) was used to study the morphological properties of the prepared samples (size and shape). All samples have a spherical shape of the Ag NPs with different sizes. An enhancement of the Ag NPs size occurs by either increasing the MW power, increasing the MW heating time, or decreasing the PVP ratio. The electrical properties of the same samples were studied using the vector network analyzer (VNA). The 30s samples are not stable, while the 90s samples give stable measurements, and repeating measurement process after a long time (up to 7 months) gives approximately the same results for these 90s samples.