{"title":"Quantum gravity correction to the thermodynamic quantities of the charged dRGT black hole","authors":"G. Gecim","doi":"10.3906/fiz-2009-8","DOIUrl":"https://doi.org/10.3906/fiz-2009-8","url":null,"abstract":"","PeriodicalId":46003,"journal":{"name":"Turkish Journal of Physics","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47887565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to investigate the structural, vibrational, electronic, and mechanical features of single-layer ReTe2first-principles calculations are performed. Dynamical stability analyses reveal that single-layer ReTe2crystallize in adistorted phase while its 1H and 1T phases are dynamically unstable. Raman spectrum calculations show that single-layer distorted phase of ReTe2exhibits 18 Raman peaks similar to those of ReS2and ReSe2. Electronically, single-layerReTe2is shown to be an indirect gap semiconductor with a suitable band gap for optoelectronic applications. In addition,it is found that the formation of Re-units in the crystal induces anisotropic mechanical parameters. The in-plane stiffnessand Poisson ratio are shown to be significantly dependent on the lattice orientation. Our findings indicate that single-layer form of ReTe2can only crystallize in a dynamically stable distorted phase formed by the Re-units. Single-layer ofdistorted ReTe2can be a potential in-plane anisotropic material for various nanotechnology applications.
{"title":"Stable anisotropic single-layer of ReTe2: a first principles prediction","authors":"M. Yagmurcukardes","doi":"10.3906/fiz-2004-17","DOIUrl":"https://doi.org/10.3906/fiz-2004-17","url":null,"abstract":"In order to investigate the structural, vibrational, electronic, and mechanical features of single-layer ReTe2first-principles calculations are performed. Dynamical stability analyses reveal that single-layer ReTe2crystallize in adistorted phase while its 1H and 1T phases are dynamically unstable. Raman spectrum calculations show that single-layer distorted phase of ReTe2exhibits 18 Raman peaks similar to those of ReS2and ReSe2. Electronically, single-layerReTe2is shown to be an indirect gap semiconductor with a suitable band gap for optoelectronic applications. In addition,it is found that the formation of Re-units in the crystal induces anisotropic mechanical parameters. The in-plane stiffnessand Poisson ratio are shown to be significantly dependent on the lattice orientation. Our findings indicate that single-layer form of ReTe2can only crystallize in a dynamically stable distorted phase formed by the Re-units. Single-layer ofdistorted ReTe2can be a potential in-plane anisotropic material for various nanotechnology applications.","PeriodicalId":46003,"journal":{"name":"Turkish Journal of Physics","volume":"44 1","pages":"450-457"},"PeriodicalIF":2.1,"publicationDate":"2020-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3906/fiz-2004-17","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70203430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Energy is undoubtedly one of our most important demands whose consumption is constantly increasingand will continue to increase soon. One of the most important factors in attaining the required energy is to providehigh efficiency at a low cost with the help of new technological improvements by evaluating wastes. Energy demandcould be achieved for a relatively large thermoelectric power value by recycling the Peltier modules from waste onesand adjusting their properties with nanotechnology. For this aim, thermoelectric thin film modules were grown onsilicon (Si), glass, and Kapton substrates with thermal evaporation method by using two different BiTeSb/BiTeSealloy materials which are placed in industrial Peltiers as the p- and n-type semiconductor. The thin films structuraland morphological characterizations were investigated by X-ray diffraction (XRD) and scanning electron microscopy(SEM) experiments reveal fine surface with uniformly distributed continuous structure. Seebeck coefficiency (|S|) of thesubstantial modules were investigated by forming certain temperature gradients on them making serial connections usinga homemade measurement setup. |S|=143.86μV/K is obtained for the thermoelectric module on Si substrate and 44.96μV/K and 24.98μV/K are calculated for glass and Kapton, respectively.
{"title":"Unraveling energy consumption by using low-cost and reevaluated thermoelectricThin Films","authors":"G. D. Yüzüak, S. Özkan, E. Yüzüak","doi":"10.3906/fiz-2002-7","DOIUrl":"https://doi.org/10.3906/fiz-2002-7","url":null,"abstract":"Energy is undoubtedly one of our most important demands whose consumption is constantly increasingand will continue to increase soon. One of the most important factors in attaining the required energy is to providehigh efficiency at a low cost with the help of new technological improvements by evaluating wastes. Energy demandcould be achieved for a relatively large thermoelectric power value by recycling the Peltier modules from waste onesand adjusting their properties with nanotechnology. For this aim, thermoelectric thin film modules were grown onsilicon (Si), glass, and Kapton substrates with thermal evaporation method by using two different BiTeSb/BiTeSealloy materials which are placed in industrial Peltiers as the p- and n-type semiconductor. The thin films structuraland morphological characterizations were investigated by X-ray diffraction (XRD) and scanning electron microscopy(SEM) experiments reveal fine surface with uniformly distributed continuous structure. Seebeck coefficiency (|S|) of thesubstantial modules were investigated by forming certain temperature gradients on them making serial connections usinga homemade measurement setup. |S|=143.86μV/K is obtained for the thermoelectric module on Si substrate and 44.96μV/K and 24.98μV/K are calculated for glass and Kapton, respectively.","PeriodicalId":46003,"journal":{"name":"Turkish Journal of Physics","volume":"44 1","pages":"442-449"},"PeriodicalIF":2.1,"publicationDate":"2020-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45401470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By using the Parikh-Wilczek (PW) quantum tunneling method, the Hawking radiation of black holes in massive gravity is investigated, the emission rate of particles and the black hole entropy are calculated. It is shown that the emission spectrum is not purely thermal, depends on the increment of the black hole entropy, consists with an accurate unitary theory and supports the standpoint of information conservation. Unlike other modified gravities, the entropy of the massive gravity black hole unexpectedly conforms to the area law just as that of Einstein gravity black hole.
{"title":"Tunneling radiation and quantum entropy of a massive gravity black hole","authors":"Gu-Qiang Li, Yi Zhuang","doi":"10.3906/fiz-2005-1","DOIUrl":"https://doi.org/10.3906/fiz-2005-1","url":null,"abstract":"By using the Parikh-Wilczek (PW) quantum tunneling method, the Hawking radiation of black holes in massive gravity is investigated, the emission rate of particles and the black hole entropy are calculated. It is shown that the emission spectrum is not purely thermal, depends on the increment of the black hole entropy, consists with an accurate unitary theory and supports the standpoint of information conservation. Unlike other modified gravities, the entropy of the massive gravity black hole unexpectedly conforms to the area law just as that of Einstein gravity black hole.","PeriodicalId":46003,"journal":{"name":"Turkish Journal of Physics","volume":"44 1","pages":"458-464"},"PeriodicalIF":2.1,"publicationDate":"2020-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3906/fiz-2005-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43812772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We give a pedagogical introduction to time-independent scattering theory in one dimension focusing on the basic properties and recent applications of transfer matrices. In particular, we begin surveying some basic notions of potential scattering such as transfer matrix and its analyticity, multi-delta-function and locally periodic potentials, Jost solutions, spectral singularities and their time-reversal, and unidirectional reflectionlessness and invisibility. We then offer a simple derivation of the Lippmann-Schwinger equation and Born series, and discuss the Born approximation. Next, we outline a recently developed dynamical formulation of time-independent scattering theory in one dimension. This formulation relates the transfer matrix and therefore the solution of the scattering problem for a given potential to the solution of the time-dependent Schrodinger equation for an effective non-unitary two-level quantum system. We provide a self-contained treatment of this formulation and some of its most important applications. Specifically, we use it to devise a powerful alternative to the Born series and Born approximation, derive dynamical equations for the reflection and transmission amplitudes, discuss their application in constructing exact tunable unidirectionally invisible potentials, and use them to provide an exact solution for single-mode inverse scattering problems. The latter, which has important applications in designing optical devices with a variety of functionalities, amounts to providing an explicit construction for a finite-range complex potential whose reflection and transmission amplitudes take arbitrary prescribed values at any given wavenumber.
{"title":"Transfermatrix in scattering theory: a survey of basic properties and recent developments","authors":"A. Mostafazadeh","doi":"10.3906/fiz-2009-14","DOIUrl":"https://doi.org/10.3906/fiz-2009-14","url":null,"abstract":"We give a pedagogical introduction to time-independent scattering theory in one dimension focusing on the basic properties and recent applications of transfer matrices. In particular, we begin surveying some basic notions of potential scattering such as transfer matrix and its analyticity, multi-delta-function and locally periodic potentials, Jost solutions, spectral singularities and their time-reversal, and unidirectional reflectionlessness and invisibility. We then offer a simple derivation of the Lippmann-Schwinger equation and Born series, and discuss the Born approximation. Next, we outline a recently developed dynamical formulation of time-independent scattering theory in one dimension. This formulation relates the transfer matrix and therefore the solution of the scattering problem for a given potential to the solution of the time-dependent Schrodinger equation for an effective non-unitary two-level quantum system. We provide a self-contained treatment of this formulation and some of its most important applications. Specifically, we use it to devise a powerful alternative to the Born series and Born approximation, derive dynamical equations for the reflection and transmission amplitudes, discuss their application in constructing exact tunable unidirectionally invisible potentials, and use them to provide an exact solution for single-mode inverse scattering problems. The latter, which has important applications in designing optical devices with a variety of functionalities, amounts to providing an explicit construction for a finite-range complex potential whose reflection and transmission amplitudes take arbitrary prescribed values at any given wavenumber.","PeriodicalId":46003,"journal":{"name":"Turkish Journal of Physics","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43857656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Advantages of quantum effects in several technologies, such as computation and communication, have already been well appreciated, and some devices, such as quantum computers and communication links, exhibiting superiority to their classical counterparts have been demonstrated. The close relationship between information and energy motivates us to explore if similar quantum benefits can be found in energy technologies. Investigation of performance limits for a broader class of information-energy machines is the subject of the rapidly emerging field of quantum thermodynamics. Extension of classical thermodynamical laws to the quantum realm is far from trivial. This short review presents some of the recent efforts in this fundamental direction and focuses on quantum heat engines and their efficiency bounds when harnessing energy from non-thermal resources, specifically those containing quantum coherence and correlations.
{"title":"Quantum thermodynamics and quantum coherence engines","authors":"A. Tuncer, Ozgur Esat Mustecapliouglu","doi":"10.3906/fiz-2009-12","DOIUrl":"https://doi.org/10.3906/fiz-2009-12","url":null,"abstract":"Advantages of quantum effects in several technologies, such as computation and communication, have already been well appreciated, and some devices, such as quantum computers and communication links, exhibiting superiority to their classical counterparts have been demonstrated. The close relationship between information and energy motivates us to explore if similar quantum benefits can be found in energy technologies. Investigation of performance limits for a broader class of information-energy machines is the subject of the rapidly emerging field of quantum thermodynamics. Extension of classical thermodynamical laws to the quantum realm is far from trivial. This short review presents some of the recent efforts in this fundamental direction and focuses on quantum heat engines and their efficiency bounds when harnessing energy from non-thermal resources, specifically those containing quantum coherence and correlations.","PeriodicalId":46003,"journal":{"name":"Turkish Journal of Physics","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3906/fiz-2009-12","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49523962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present optical identification of deep level defects in as-grown and annealed GaBixAs1−x (x = 0, 0.013 and 0.015) alloys grown at different temperatures (220 °C and 320 °C) by using photo-modulated reflectance (PR) spectroscopy and photoluminescence (PL). The PR measurements are employed at aboveand below-bandgap excitations, and the PR line-shape is analyzed by the third derivative functional form (TDFF). The PR at below-bandgap excitation reveals transitions at 0.757 ±0.001 eV and 0.710 ±0.002 eV at 30K and 300K, respectively. Franz-Keldysh oscillations are observed in all samples under above-bandgap excitation at PR measurements, and the built-in electric field, which may originate from the charged As-antisite defects is calculated from local extrema points in the PR spectra. The decrease in the built-in electric field after thermal annealing is explained with decreased point defect density.
{"title":"Investigating above-bandgap and below-bandgap optical transition in GaBiAs epilayers by photoreflectance spectroscopy","authors":"Ömer Dönmez, A. Erol","doi":"10.3906/fiz-2003-17","DOIUrl":"https://doi.org/10.3906/fiz-2003-17","url":null,"abstract":"We present optical identification of deep level defects in as-grown and annealed GaBixAs1−x (x = 0, 0.013 and 0.015) alloys grown at different temperatures (220 °C and 320 °C) by using photo-modulated reflectance (PR) spectroscopy and photoluminescence (PL). The PR measurements are employed at aboveand below-bandgap excitations, and the PR line-shape is analyzed by the third derivative functional form (TDFF). The PR at below-bandgap excitation reveals transitions at 0.757 ±0.001 eV and 0.710 ±0.002 eV at 30K and 300K, respectively. Franz-Keldysh oscillations are observed in all samples under above-bandgap excitation at PR measurements, and the built-in electric field, which may originate from the charged As-antisite defects is calculated from local extrema points in the PR spectra. The decrease in the built-in electric field after thermal annealing is explained with decreased point defect density.","PeriodicalId":46003,"journal":{"name":"Turkish Journal of Physics","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3906/fiz-2003-17","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44689711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to realize skyrmion-based next-generation logic and memory devices, investigating the impact of material parameters on skyrmion formation is essential. Capping magnetic thin layers for the purposes of both preventing oxidation and/or enhancing crystal structure has an influence on chiral spin texture of the layer. In this paper, we have carried out a systematic computational study on magnetic skyrmion and domain-wall formation in which 2-atomic layer of Co, deposited on Pt(111) substrate and capped by certain (Ta, Ir, and Pt) 5d elements with various thicknesses. We have determined the magnetic topography of the structures by simulations based on DFT-calculated parameters; micromagnetic Dzyaloshinskii-Moriya interaction, exchange interaction, and magnetic anisotropy coefficients. We have revealed the influence of capping material and thickness on the chiral spin texture. We anticipate that our predictions provide a rational basis for skyrmion-based devices in which skyrmions are used as logic or information element.
{"title":"Influence of capping layer on skyrmion and domain-wall formation in Co/Pt(111)","authors":"C. Deger","doi":"10.3906/fiz-1912-2","DOIUrl":"https://doi.org/10.3906/fiz-1912-2","url":null,"abstract":"In order to realize skyrmion-based next-generation logic and memory devices, investigating the impact of material parameters on skyrmion formation is essential. Capping magnetic thin layers for the purposes of both preventing oxidation and/or enhancing crystal structure has an influence on chiral spin texture of the layer. In this paper, we have carried out a systematic computational study on magnetic skyrmion and domain-wall formation in which 2-atomic layer of Co, deposited on Pt(111) substrate and capped by certain (Ta, Ir, and Pt) 5d elements with various thicknesses. We have determined the magnetic topography of the structures by simulations based on DFT-calculated parameters; micromagnetic Dzyaloshinskii-Moriya interaction, exchange interaction, and magnetic anisotropy coefficients. We have revealed the influence of capping material and thickness on the chiral spin texture. We anticipate that our predictions provide a rational basis for skyrmion-based devices in which skyrmions are used as logic or information element.","PeriodicalId":46003,"journal":{"name":"Turkish Journal of Physics","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45446832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the manufacture of Bi2 Te3−x Sex -based elements using two sources of the deposited substance, they were initially annealed at a temperature of 150–200 °Ñ in a low vacuum. Heat treatment led to a slight increase in short circuit current and an increase in open circuit voltage. When the elements were heated in high vacuum, as well as in atmospheres of argon, nitrogen, hydrogen, helium and other gases, irreversible changes in the characteristics were not detected. Heat treatment of elements at a temperature of 100–150 °C in oxygen always improves their performance. It is assumed that annealing stimulates the growth of the transition layer at the interface. Annealing of solar cells based on Si-Bi2 Te3−x Sex at an even higher temperature leads to a further irreversible deterioration of their characteristics.
{"title":"Influence of annealing on photoelectric characteristics and stability of elements based on Si-Bi2Te3−xSex","authors":"G. Ahmadov","doi":"10.3906/fiz-2002-4","DOIUrl":"https://doi.org/10.3906/fiz-2002-4","url":null,"abstract":"In the manufacture of Bi2 Te3−x Sex -based elements using two sources of the deposited substance, they were initially annealed at a temperature of 150–200 °Ñ in a low vacuum. Heat treatment led to a slight increase in short circuit current and an increase in open circuit voltage. When the elements were heated in high vacuum, as well as in atmospheres of argon, nitrogen, hydrogen, helium and other gases, irreversible changes in the characteristics were not detected. Heat treatment of elements at a temperature of 100–150 °C in oxygen always improves their performance. It is assumed that annealing stimulates the growth of the transition layer at the interface. Annealing of solar cells based on Si-Bi2 Te3−x Sex at an even higher temperature leads to a further irreversible deterioration of their characteristics.","PeriodicalId":46003,"journal":{"name":"Turkish Journal of Physics","volume":"44 1","pages":"348-355"},"PeriodicalIF":2.1,"publicationDate":"2020-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43952232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We consider the problem of recovering the model of a complex network of interacting dynamical units from time series of observations. We focus on typical networks which exhibit heterogeneous degrees, i.e. where the number of connections varies widely across the network, and the coupling strength for a single interaction is small. In these networks, the behavior of each unit varies according to their connectivity. Under these mild assumptions, our method provides an effective network reconstruction of the network dynamics. The method is robust to a certain size of noise and only requires relatively short time series on the state variable of most nodes to determine: how well-connected a particular node is, the distribution of the nodes’ degrees in the network, and the underlying dynamics.
{"title":"Network dynamics reconstruction from data","authors":"Deniz Eroglu","doi":"10.3906/fiz-2004-7","DOIUrl":"https://doi.org/10.3906/fiz-2004-7","url":null,"abstract":"We consider the problem of recovering the model of a complex network of interacting dynamical units from time series of observations. We focus on typical networks which exhibit heterogeneous degrees, i.e. where the number of connections varies widely across the network, and the coupling strength for a single interaction is small. In these networks, the behavior of each unit varies according to their connectivity. Under these mild assumptions, our method provides an effective network reconstruction of the network dynamics. The method is robust to a certain size of noise and only requires relatively short time series on the state variable of most nodes to determine: how well-connected a particular node is, the distribution of the nodes’ degrees in the network, and the underlying dynamics.","PeriodicalId":46003,"journal":{"name":"Turkish Journal of Physics","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2020-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48549622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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