Department of Physics
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Item Study of Electronic Performance of Ferroelectric Materials for Potential Application in Diode Based Devices(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2024) EIMAN RASHEED; CUI/SP23-RPH-020/LHR; Dr. Amna Mir; LHR TP 9640Bismuth ferrites that are doped with rare-earth and processed by sol-gel method with citric acid as a chelating agent shows a greatly enhanced ferroelectric behavior thus making these materials appropriate for diode based applications. Gadolinium, yttrium, and samarium are examples of rare-earth elements that, when added to bismuth ferrite (BiFeO₃), enhance its physical properties. The doping of Gadolinium improves bandwidth and decreases resistance, while yttrium ensures that polarization is not lost and the device stays functional regardless of frequency. On the other hand, samarium-doped bismuth ferrite has proliferated the market with its great ferroelectricity, lower leakage current and quick charge transport mechanism all integrated in it. Correlating its absorption peak of UV-Visible light at 279 nm, with a bandgap of 2.6 eV, development in devices that use light such as LED will not be a challenge, moreover, its I-V characteristic give rectifying action which is necessary for diodes operation. These results accentuate the potential of rare-earth-doped bismuth ferrites, particularly samarium-doped variants, in developments of devices such as memory units, photodiodes and devices that utilize light in an efficient manner.Item First Principle Study of Structural, Electronic and Magnetic Properties of Doped TbMnO3 for Transportation in Spintronic Devices(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2023) Sayyda Rimsha Irfan; CIIT/SP22-RPH-023/LHR; Dr. Kashif Tufail; LHR TP 8786Multiferroic Terbium Magnate, TbMnO3 (TMO), is one of the most investigated compounds for advances in spintronic devices. Single-phase multiferroic TMO can play an important role in the development of spintronics random access memory (RAM) due to its spin-polarized electronic, magnetic, and dielectric properties. However, the major challenge in the field of spintronic RAM technology is to generate a balanced magnetization of 25 MA/cm, more than 80% spin polarization at the Fermi level, and suitable dielectric constant in the range of 10 to 52. The present research work explores the structural, spin-polarized electronic, dielectric, and magnetic properties of Dysprosium (Dy) doped TMO structure for spintronic memory device application using first-principles calculations. The generalized gradient approximation (GGA) with Perdew-Burke Ernzerhof (PBE) is used to perform numerical simulation using CASTEP numerical coding. Dy impurities in TMO structure change the lattice constant, volume, and bond length, which profoundly affects the material's properties. The band gap in the spin-up and spin-down states is altered by the inclusion of Dy atoms due to increase in the energy states. The additional energy levels significantly enhance the spin polarization at the Fermi level, which is more favorable for spintronic devices. The addition of Dy-dopants as mono, di and triatomic in Pure TMO 2x2x2 super cell results in decrease in the magnetic moment. The half metallicity or 86.3 % spin polarization at the Fermi level, high dielectric constant of 1520.65, appropriate magnetism of 34.69 MA/cm has been observed for triatomic Dy doped TMO material in orthorhombic phase. Thus, triatomic Dy-doped TMO is a potential single-phase material spintronic ferro memory device applications.Item Hydrothermal Synthesis of Nickel Doped Zinc Oxide (NixZn1-xO where x=0, 0.1, 0.2, 0.3, 0.4): Experimental and DFT Study of Structural, Electronic and Magnetic Parameters(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Usman Zakir; CIIT/SP21-RPH-011/LHR; Prof. Dr. Muhammad Asif; LHR TP 8314Structural, electronic and magnetic properties of nickel doped zinc oxide (NixZn1-xO) are studied by employing both experimental as well as theoretical approach. Experimentally the Hydrothermal method was employed for the synthesis and different experimental characterizations were used to investigate its different properties. Theoretically we worked under the frame wok of DFT using approximations like LDA. XRD confirms the hexagonal structure of sample with lattice constant of 3.23804Å belonging to space group P63mc. FTIR spectrum revealed the absorption peak at 536 cm-1 which is due to octahedral site in the nickel doped zinc oxide. SEM was used for the investigation of surface morphology and showed the agglomeration with non- uniform particle sizes. Theoretically DFT was used and all work done using Local Density Approximation. It was revealed that LDA describes the non- magnetic structure of zinc oxide, further it can be clarified by DOS in spin up and spin down so net magnetic moment is almost zeroItem Synthesis and Characterization of Graphene Quantum Dots for Electronic and Photonics Devices(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Ammara Javed; CIIT/SP20-RPH-063/LHR; Dr. Abdul Sattar; LHR TP 7720People interpret the term "micro world" in a variety of ways. The surface-to-volume relationship is defined as the intermediary between atoms and solids. When chemists first introduced nanotechnology, no one knew what it was. They used physicists to alter the structures. Richard Feynman, a physicist, was awarded a Nobel prize for his contributions to nanotechnology in 1959. After winning the Nobel Prize for his amazing invention, the Noble Prize laureate declared during an American Physical Society meeting that "there is plenty of room at the bottom." Biology has traditionally been molecular, with important multidisciplinary study areas such as DNA, protein, and cellular machinery. The nanoworld idea is founded on the convergence of a genuine scientific or technological combination. Despite the fact that the wave-corpuscle duality-based principles of quantum physics are not clearly apparent. With the exception of semiconductors and lasers. Quantum effects will be applied in a variety of applications in the future. "Nano-Technology is a science, engineering, and technology that takes place on the nanoscale, which ranges from 1 to 10 nanometers." A billionth of a meter, or 10-9 of a meter, is one nanometer, which is difficult to comprehend. The capacity to observe and manipulate individual atoms and molecules is required. Atoms make up everything on the planet. However, seeing a nanometer-sized object with the naked eye is impossible. As a result, microscopes such as the Scanning Tunneling Microscope (STM).