Pub Date : 2022-10-07DOI: 10.1088/2399-6528/ac9884
Akib Zaman, Homayra Tabassum Mumu, Rafat Hossain Aunkon, Faharia Hasan Bhuiyan, A. Sharif
Density Functional Theory with Hubbard U parameter (DFT + U) was used to study the impact of C (6.25%) and Fe (12.5%) mono- and co-doping on wurtzite GaN, which modified the structural, electrical, magnetic, and optical properties. Under conditions of abundant N, the doping effect led to an increase in thermodynamic formability. For all the dopant combinations, a reduction in the band gap was seen. GaN becomes a ferrimagnetic material because of co-doping. The performance of the C and Fe co-doped GaN was the best due to the redshift of the absorption edge, which resulted in the improved absorption of near ultraviolet (UV) and visible-infrared (VIS-IR) photonic energies for both monodoping and co-doping structures. The doping caused an increase in the refractive index and dielectric constant. For C and Fe co-doped GaN, the maximum static dielectric constant and refractive index were 19.58 and 4.45, respectively. The findings of this work therefore point to the possible use of C, Fe mono- and co-doped GaN in UV, IR optoelectronic and photonic devices.
{"title":"Improving optical properties of wurtzite GaN with C and Fe co-doping: A DFT+U study","authors":"Akib Zaman, Homayra Tabassum Mumu, Rafat Hossain Aunkon, Faharia Hasan Bhuiyan, A. Sharif","doi":"10.1088/2399-6528/ac9884","DOIUrl":"https://doi.org/10.1088/2399-6528/ac9884","url":null,"abstract":"Density Functional Theory with Hubbard U parameter (DFT + U) was used to study the impact of C (6.25%) and Fe (12.5%) mono- and co-doping on wurtzite GaN, which modified the structural, electrical, magnetic, and optical properties. Under conditions of abundant N, the doping effect led to an increase in thermodynamic formability. For all the dopant combinations, a reduction in the band gap was seen. GaN becomes a ferrimagnetic material because of co-doping. The performance of the C and Fe co-doped GaN was the best due to the redshift of the absorption edge, which resulted in the improved absorption of near ultraviolet (UV) and visible-infrared (VIS-IR) photonic energies for both monodoping and co-doping structures. The doping caused an increase in the refractive index and dielectric constant. For C and Fe co-doped GaN, the maximum static dielectric constant and refractive index were 19.58 and 4.45, respectively. The findings of this work therefore point to the possible use of C, Fe mono- and co-doped GaN in UV, IR optoelectronic and photonic devices.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44572534","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}
Pub Date : 2022-10-05DOI: 10.1088/2399-6528/ac97dd
K. Asakawa, T. Kawauchi, K. Fukutani
The Verwey transition on Fe3O4(111) surface was investigated using nuclear resonant x-ray scattering (NRS). Measurements were conducted below (85 K) and above (297 and 500 K) the Verwey transition temperature. The internal magnetic field estimated from the NRS frequency spectra agreed with that of bulk Fe3O4 at all measured temperatures. A clear change in the intensity ratio of the two peaks in the frequency spectra was observed across the Verwey transition. The results indicate that despite the presence of the peculiar surface electronic states which makes the changes in the electronic properties across the Verwey transition temperature blurred, the hyperfine parameters of the (111) surface show a clear change across the Verwey transition temperature.
{"title":"Temperature dependence of the hyperfine parameters on Fe3O4(111) surfaces","authors":"K. Asakawa, T. Kawauchi, K. Fukutani","doi":"10.1088/2399-6528/ac97dd","DOIUrl":"https://doi.org/10.1088/2399-6528/ac97dd","url":null,"abstract":"The Verwey transition on Fe3O4(111) surface was investigated using nuclear resonant x-ray scattering (NRS). Measurements were conducted below (85 K) and above (297 and 500 K) the Verwey transition temperature. The internal magnetic field estimated from the NRS frequency spectra agreed with that of bulk Fe3O4 at all measured temperatures. A clear change in the intensity ratio of the two peaks in the frequency spectra was observed across the Verwey transition. The results indicate that despite the presence of the peculiar surface electronic states which makes the changes in the electronic properties across the Verwey transition temperature blurred, the hyperfine parameters of the (111) surface show a clear change across the Verwey transition temperature.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43847090","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}
Pub Date : 2022-10-04DOI: 10.1088/2399-6528/ac9774
A. Camacho de la Rosa, R. Esquivel-Sirvent
We present a study of the causal response of non-Fourier heat conduction by introducing a dispersive generalized thermal susceptibility and show it obeys Kramers-Kronig relations. In particular, we discuss the Cattaneo-Vernotte and the dual-phase lag models. The constitutive equations are written as a linear response theory and determine the conditions for which the dual-phase lag model does not satisfy Kramers-Kronig relations. An alternative model is presented to describe non-Fourier transport using the similarity with the causal response of viscoelastic materials to avoid this unphysical issue.
{"title":"Causality in non-fourier heat conduction","authors":"A. Camacho de la Rosa, R. Esquivel-Sirvent","doi":"10.1088/2399-6528/ac9774","DOIUrl":"https://doi.org/10.1088/2399-6528/ac9774","url":null,"abstract":"We present a study of the causal response of non-Fourier heat conduction by introducing a dispersive generalized thermal susceptibility and show it obeys Kramers-Kronig relations. In particular, we discuss the Cattaneo-Vernotte and the dual-phase lag models. The constitutive equations are written as a linear response theory and determine the conditions for which the dual-phase lag model does not satisfy Kramers-Kronig relations. An alternative model is presented to describe non-Fourier transport using the similarity with the causal response of viscoelastic materials to avoid this unphysical issue.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41796103","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}
Pub Date : 2022-10-03DOI: 10.1088/2399-6528/ac9728
J. Armstrong
Classical molecular dynamics (MD) plays a central role in understanding structural and dynamical phenomena across all disciplines of physical chemistry. These models can be used to interpret experimental data, or as a method of study in their own right. Their legitimacy however rests solely on the accuracy of the underlying force-field, and so the parameterisation of these force-fields is the most crucial aspect of any study. The typical methods of parameterisation are structural or thermodynamic in nature, however this perspective article will examine a little used metric of parametersation; that of neutron spectroscopy, and in particular quasi-elastic neutron spectroscopy (QENS). QENS data contains self-correlation information for the hydrogen atoms of a system, over a wide range of distances and time-scales. These scales are relevant for local and global diffusion and rotation, thus pairing very well to the scales of molecular dynamics for organic systems. This article focuses in particular on the parameterisation of models of porous and surface catalysts. This area is a particularly rich field for the application of QENS, however there is a distinct lack of accurate classical force-fields currently.
{"title":"Neutron spectroscopy as a method for classical force-field parameterization: Past methods, present successes and future challenges","authors":"J. Armstrong","doi":"10.1088/2399-6528/ac9728","DOIUrl":"https://doi.org/10.1088/2399-6528/ac9728","url":null,"abstract":"Classical molecular dynamics (MD) plays a central role in understanding structural and dynamical phenomena across all disciplines of physical chemistry. These models can be used to interpret experimental data, or as a method of study in their own right. Their legitimacy however rests solely on the accuracy of the underlying force-field, and so the parameterisation of these force-fields is the most crucial aspect of any study. The typical methods of parameterisation are structural or thermodynamic in nature, however this perspective article will examine a little used metric of parametersation; that of neutron spectroscopy, and in particular quasi-elastic neutron spectroscopy (QENS). QENS data contains self-correlation information for the hydrogen atoms of a system, over a wide range of distances and time-scales. These scales are relevant for local and global diffusion and rotation, thus pairing very well to the scales of molecular dynamics for organic systems. This article focuses in particular on the parameterisation of models of porous and surface catalysts. This area is a particularly rich field for the application of QENS, however there is a distinct lack of accurate classical force-fields currently.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47724629","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}
Pub Date : 2022-09-21DOI: 10.1088/2399-6528/ac93e6
S. Sakhi
The viability of the phase with spontaneous breaking of scale symmetry observed in the infinite N limit of the O(N) symmetric phi-six theory in three dimensions is scrutinized against quantum corrections at the next-to-leading order in 1/N expansion. It is shown that inclusion of such corrections disrupt the flatness and the global real-valuedness of the effective potential which develops an imaginary part for some values of the fields in a strong coupling regime that covers the BMB and the nontrivial ultraviolet fixed points. This signals instability of the phase with spontaneously broken approximate scale invariance which is doomed to decay by higher 1/N radiative corrections.
{"title":"Instability of the φ⃗23 model with spontaneously broken scale symmetry","authors":"S. Sakhi","doi":"10.1088/2399-6528/ac93e6","DOIUrl":"https://doi.org/10.1088/2399-6528/ac93e6","url":null,"abstract":"The viability of the phase with spontaneous breaking of scale symmetry observed in the infinite N limit of the O(N) symmetric phi-six theory in three dimensions is scrutinized against quantum corrections at the next-to-leading order in 1/N expansion. It is shown that inclusion of such corrections disrupt the flatness and the global real-valuedness of the effective potential which develops an imaginary part for some values of the fields in a strong coupling regime that covers the BMB and the nontrivial ultraviolet fixed points. This signals instability of the phase with spontaneously broken approximate scale invariance which is doomed to decay by higher 1/N radiative corrections.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47287669","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}
Pub Date : 2022-09-16DOI: 10.1088/2399-6528/ac92c2
Nihad Kamar, Marie Le Page Mostefa, H. Muhr, P. Jost
This paper deals with the influence of guided ultrasonic waves on heat transfer. Two piezoelectric transducers, whose structure can be vibrated at different powers and at their resonant frequency in the ultrasonic range of 27–45 kHz, were placed on the plates of a heat exchanger to inhibit the formation of a mineral deposit. These waves were set to diffuse only into the metal plates of the exchanger. During these tests, an increase in the heat transfer between the two fluids was directly observed on the continuous recording of the outlet temperature, on the calculations of the global exchange coefficient, and on the flow exchanged between the two fluids in the laminar regime. Tests are presented in this article, tests in the presence of the 45 kHz transducer, another with a 27 kHz transducer, and which combines the two have a different positioning on the exchanger. The results obtained from the ultrasonic guided waves are similar to the classical ultrasonic waves.
{"title":"Influence of ultrasonic treatment on heat transfer in the heat exchanger","authors":"Nihad Kamar, Marie Le Page Mostefa, H. Muhr, P. Jost","doi":"10.1088/2399-6528/ac92c2","DOIUrl":"https://doi.org/10.1088/2399-6528/ac92c2","url":null,"abstract":"This paper deals with the influence of guided ultrasonic waves on heat transfer. Two piezoelectric transducers, whose structure can be vibrated at different powers and at their resonant frequency in the ultrasonic range of 27–45 kHz, were placed on the plates of a heat exchanger to inhibit the formation of a mineral deposit. These waves were set to diffuse only into the metal plates of the exchanger. During these tests, an increase in the heat transfer between the two fluids was directly observed on the continuous recording of the outlet temperature, on the calculations of the global exchange coefficient, and on the flow exchanged between the two fluids in the laminar regime. Tests are presented in this article, tests in the presence of the 45 kHz transducer, another with a 27 kHz transducer, and which combines the two have a different positioning on the exchanger. The results obtained from the ultrasonic guided waves are similar to the classical ultrasonic waves.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43617638","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}
Pub Date : 2022-09-08DOI: 10.1088/2399-6528/acd6d7
A. Schlatter, R. Kastner
This is a comprehensive review of new developments in entropic gravity in light of the Relativistic Transactional Interpretation (RTI). A transactional approach to spacetime events can give rise in a natural way to entropic gravity (in the way originally proposed by Eric Verlinde) while also overcoming extant objections to that research program. The theory also naturally gives rise to a Cosmological Constant and to Modified Newtonian Dynamics (MOND) and thus provides a physical explanation for the phenomena historically attributed to ‘dark energy’ and ‘dark matter’.
{"title":"Gravity from transactions: fulfilling the entropic gravity program","authors":"A. Schlatter, R. Kastner","doi":"10.1088/2399-6528/acd6d7","DOIUrl":"https://doi.org/10.1088/2399-6528/acd6d7","url":null,"abstract":"This is a comprehensive review of new developments in entropic gravity in light of the Relativistic Transactional Interpretation (RTI). A transactional approach to spacetime events can give rise in a natural way to entropic gravity (in the way originally proposed by Eric Verlinde) while also overcoming extant objections to that research program. The theory also naturally gives rise to a Cosmological Constant and to Modified Newtonian Dynamics (MOND) and thus provides a physical explanation for the phenomena historically attributed to ‘dark energy’ and ‘dark matter’.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44075390","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}
Pub Date : 2022-09-07DOI: 10.1088/2399-6528/ac9034
R. Singh, M. Dutta, M. Stroscio
In this paper we evaluate the electric field—velocity relation for strong electron—LO phonon coupled 2D materials namely HfS2, HfSe2, ZrS2 and ZrSe2 by applying Thornber—Feynman (TF) formalism applied to the case of the 2D Fröhlich polaron. We demonstrate that the generally-accepted Fermi’s Golden Rule based approach breaks down for these strongly coupled materials. We predict ZrSe2 has highest mobility of 449 cm2/V -s at room temperature followed by HfSe2 with 240 cm2/V -s whereas other materials have below 100 cm2/V -s.
{"title":"Electric field – velocity relation for strongly coupled Fröhlich polaron in emerging 2D materials","authors":"R. Singh, M. Dutta, M. Stroscio","doi":"10.1088/2399-6528/ac9034","DOIUrl":"https://doi.org/10.1088/2399-6528/ac9034","url":null,"abstract":"In this paper we evaluate the electric field—velocity relation for strong electron—LO phonon coupled 2D materials namely HfS2, HfSe2, ZrS2 and ZrSe2 by applying Thornber—Feynman (TF) formalism applied to the case of the 2D Fröhlich polaron. We demonstrate that the generally-accepted Fermi’s Golden Rule based approach breaks down for these strongly coupled materials. We predict ZrSe2 has highest mobility of 449 cm2/V -s at room temperature followed by HfSe2 with 240 cm2/V -s whereas other materials have below 100 cm2/V -s.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46694732","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}
Pub Date : 2022-09-01DOI: 10.1088/2399-6528/ac8f18
Yi-Chen Lo, Xing Cheng
This work is to demonstrate a low cost and time-conserving technique to create nano-trenches by transferring nano-scale polymeric sidewalls into substrate. The polymeric sidewall is a vertically spreading layer deposited by spin-coating a polymer solution on a vertical template. By varying processing parameters such as the solution concentration or the spin-coating speed, the dimension of the sidewall can be changed, which, after pattern transfer, also changes the nano-trench dimension. In this work, high-resolution trenches of about 15 nm have been achieved after transferring straight line sidewalls into substrate. Other than straight line sidewall patterns, this method also fabricates ring-shaped patterns including circles, squares, and concentric squares. With various shapes of sidewall patterns, this technique has a potential to implement other practical applications such as fabricating high-resolution nanoimprint molds of 15 nm.
{"title":"Polymeric sidewall transfer lithography","authors":"Yi-Chen Lo, Xing Cheng","doi":"10.1088/2399-6528/ac8f18","DOIUrl":"https://doi.org/10.1088/2399-6528/ac8f18","url":null,"abstract":"This work is to demonstrate a low cost and time-conserving technique to create nano-trenches by transferring nano-scale polymeric sidewalls into substrate. The polymeric sidewall is a vertically spreading layer deposited by spin-coating a polymer solution on a vertical template. By varying processing parameters such as the solution concentration or the spin-coating speed, the dimension of the sidewall can be changed, which, after pattern transfer, also changes the nano-trench dimension. In this work, high-resolution trenches of about 15 nm have been achieved after transferring straight line sidewalls into substrate. Other than straight line sidewall patterns, this method also fabricates ring-shaped patterns including circles, squares, and concentric squares. With various shapes of sidewall patterns, this technique has a potential to implement other practical applications such as fabricating high-resolution nanoimprint molds of 15 nm.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42531181","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}
Pub Date : 2022-08-26DOI: 10.1088/2399-6528/ac8d4b
D. Dhadhal, V. Mishra, R. Thummar
This work is proposed to examine modified duobinary return to zero modulation in DWDM long haul communication system. In this framework we simulate 32 channels each channel data rate is 40 Gbps multiplexed with the channel spacing 80 GHz, 90 GHz and 100 GHz to perceive 1.2 Tbps data. This data completed transmission Distance over 250 KM by utilizing scattering remuneration strategy. This 40 Gbps data is encoded by utilizing Mach Zehnder modulator (MRZ) inferred by CW laser of power − 10 dBm, − 5 dBm, 0 dBm, 5 dBm, 10 dBm. In the system analysis, we use modified duobinary return to zero (MDRZ) in the DWDM communication long haul system.
{"title":"Implementation and analysis of 32 channel MDRZ DWDM system at narrow channel spacing","authors":"D. Dhadhal, V. Mishra, R. Thummar","doi":"10.1088/2399-6528/ac8d4b","DOIUrl":"https://doi.org/10.1088/2399-6528/ac8d4b","url":null,"abstract":"This work is proposed to examine modified duobinary return to zero modulation in DWDM long haul communication system. In this framework we simulate 32 channels each channel data rate is 40 Gbps multiplexed with the channel spacing 80 GHz, 90 GHz and 100 GHz to perceive 1.2 Tbps data. This data completed transmission Distance over 250 KM by utilizing scattering remuneration strategy. This 40 Gbps data is encoded by utilizing Mach Zehnder modulator (MRZ) inferred by CW laser of power − 10 dBm, − 5 dBm, 0 dBm, 5 dBm, 10 dBm. In the system analysis, we use modified duobinary return to zero (MDRZ) in the DWDM communication long haul system.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41973785","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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