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Öğe Dipole-Dipole Effect to Limits of Entanglement in Multipartite Spin Chain: A Monte Carlo Study(2022) Aktaş, Şahin; Duru, İzzet ParuğThe entanglement of the ferromagnetically ordered isotropic spin-1/2 chain is discussed. The analytically deriving concurrence of a two-qubit state allows focusing on the effect of dipolar interaction (D). Low fields enable tuning creation/extinction of entangled states, particularly at low temperatures. There is a joint effect of the applied field and dipolar interaction which can’t be disregarded. We perform Quantum Monte Carlo simulations on quantifying localizable entanglement (LE) in terms of upper/lower bounds. Findings reveal that D and B_z are decisive parameters on the production of entanglement including creation and extinction. A non-monotonic behavior has occurred under high fields at the critical temperature. However, strong D provides the stability of LE values concerning distance herewith conserving the unity at low temperatures under zero field. Rival regions are observed for the distant nearest neighbors, particularly odd ones.Öğe Electronic and magnetic properties of CoFe2O4 nanostructures: an ab-initio and Monte Carlo study(Elsevier, 2022) Duru, İzzet ParuğSub-magnetic ordering of CoFe2O4 spinel was elaborated through the electronic structure via ab-initio calculations. PBE-GGA was preferred to obtain band structure and density of states applying Hubbard correction. Considered magnetic states, including distinctive sub-orders, exhibited several band gaps and magnetic features. Applying the magnetic force theorem to the ground state solution, exchange coupling energies were obtained. We double-checked O(p)-Fe/Co(d) hybridizations and exchange energies of considered magnetic states contributing to FM/FiM phases. Co-O hybridizations were stronger than Fe-O. Rest couples, obviously overshadowed the contribution of oxygen-connected ions, herewith, assuring different strengths of exchange energy. Initially, FM coupled Co-Co and Fe-Fe pairs had the strongest values. Magnetocrystalline anisotropy had close-set values consistent with previous studies (0.09210385eV for Co-Co, AFM, and Fe-Fe, FM). Curie temperatures (T-c) were obtained from temperature-dependent normalized magnetization and magnetic susceptibility curves using the Monte Carlo method on a classical Heisenberg model. Exchange energies, magnetocrystalline anisotropy, and magnetic moments obtained from DFT calculations were implemented as inputs to the simulation process. The highest Tc was found to be 725 K for the FM sub-order state. Other states undergo a phase transition under 500 K and 445 K temperatures, respectively. Considered magnetic orders can occur concerning experimental conditions and production method/procedure of CoFe2O4 spinel ferrites.Öğe Investigation of the electromagnetic shielding efficiency of FeB and Fe2B: ab-initio calculations(Institute of Physics, 2024) Üşenti, Hakan; Duru, İzzet ParuğThe electromagnetic (EM) pollution that we are exposed to in our daily lives has reached levels that threaten the health of living organisms and the stable operation of sensitive systems. The most effective way to protect against this pollution is to create isolated areas framed with shielding materials that can minimize the transmission of EM radiation. The development of shielding materials with high physical endurance against external factors to meet the needs of various sectors remains a popular research topic. This process, which started with metal plates, has continued with the development of doped polymers and composite materials. In recent years, materials with 2D structures have been developed. In this study, the shielding effectiveness (SE) of FeB and Fe2B nanostructures are revealed using ab initio calculations in Perdew-Burke-ErnzerhofSol scheme. SE has been widely figuring out via optical properties which are strongly related to mechanical and electronic properties herewith magnetic phases. The ferrimagnetic FeB and Fe2B nanostructures are considered. Besides, we focus on the thickness and photon energy dependent behavior along various projections. The findings demonstrate shielding performance at levels of >20 dB. Although both materials show similar shielding performance, it is observed that Fe2B is promising when compared to FeB. This study demonstrates that FeB and Fe2B, members of the MBene family, are promising materials not only because of their superior physical and chemical properties but also because of their shielding performance.Öğe Monte Carlo simulation of distance dependent quantum entanglement in mixed XXZ Heisenberg spin-1/2 chains(Istanbul Gedik University, 2024) Duru, İzzet Paruğ; Aktaş, ŞahinThe quantum entanglement of mixed XXZ Heisenberg spin-1/2 chain is examined. We quantify localizable entanglement (LE) in terms of upper/lower bounds through Quantum Monte Carlo simulations. Loop algorithm is chosen to numerically calculate thermodynamic quantities including spin-spin correlations. The exchange coupling, Zeeman energy, and dipolar interaction are literally taken into account. Findings summarize that the strength of dipole-dipole interaction (D) and external magnetic field (Bz) are notable in entanglement formation driving creation and extinction of entanglement. The creation and extinction of entanglement depend on D and Bz. Furthermore, strong fields at the critical temperatures lead a non-monotonic/monotonic behavior introducing revival phenomena. Nevertheless, strong D provides the distance-dependent stability of LE values, preserving unity.Öğe Tracking optical properties of ZnO:Mg thin films: experimental and first principles calculations(Elsevier Science Ltd, 2022) Canci Matur, Utku; Duru, İzzet Paruğ; Akcan, DoğanAs low-cost transparent conducting oxides (TCO), ZnO based materials have been widely used in flat panels, sensors, glasses and transparent electronic systems. ZnO based thin films are preferable instead of other TCO materials such as Indium Tin Oxides (ITO) due to electrochemical stability, non-toxicity, low cost. The physical and chemical properties of ZnO based devices depend on the stoichiometry, amount of impurity (dopant), and deposition method. In this study Mg doped zinc oxide (MZO) thin films with doping ratio varying from 1% to 5% were deposited by sol-gel dip coating method to improve the physical characters by forming the grain size. Structural and optical properties were investigated by means of XRD analysis, ultraviolet-visible (UV-VIS) and photoluminescence (PL) spectroscopy. Moreover, DFTB + method was preferred to determine electronic properties based on structural information obtained from XRD analysis. Experimentally determined band-gaps were compared with theoretically calculated gap values in which oxygen vacancies are considered.
