Pub Date : 2024-09-12DOI: 10.1088/2399-6528/ad6a4c
Mark Stander
This paper shows how an application of zeta function regularisation to a physical model of quantum measurement yields a solution to the problem of wavefunction collapse. Realistic measurement dynamics based on a particle becoming non-isolated are introduced and, based on this, an outcome function is derived using the method of maximum entropy. It is shown how regularisation of an information theoretic quantity related to this outcome function leads to apparent collapse of the wavefunction. The physical principles and key assumptions that underlie this theory are discussed. Some possible experimental approaches are described.
{"title":"Deriving measurement collapse using zeta function regularisation and speculative measurement theory","authors":"Mark Stander","doi":"10.1088/2399-6528/ad6a4c","DOIUrl":"https://doi.org/10.1088/2399-6528/ad6a4c","url":null,"abstract":"This paper shows how an application of zeta function regularisation to a physical model of quantum measurement yields a solution to the problem of wavefunction collapse. Realistic measurement dynamics based on a particle becoming non-isolated are introduced and, based on this, an outcome function is derived using the method of maximum entropy. It is shown how regularisation of an information theoretic quantity related to this outcome function leads to apparent collapse of the wavefunction. The physical principles and key assumptions that underlie this theory are discussed. Some possible experimental approaches are described.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142247835","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 : 2024-09-11DOI: 10.1088/2399-6528/ad777b
M P Munguía-Martín, D Sánchez-Campos, D Mendoza-Anaya, T V K Karthik, L S Villaseñor-Cerón, M I Reyes-Valderrama and V Rodríguez-Lugo
Gas sensors are crucial for safety and well-being in various environments. Zinc oxide (ZnO) gas sensors are notable for their broad gas detection capabilities. In this study, ZnO structures were synthesized by optimized chemical precipitation method with urea, followed by a thermal treatment at 500 °C for 5, 10, 13, and 15 h. The microstructural, morphological, and CO sensing properties were examined. X-ray Diffraction analysis confirmed the hexagonal wurtzite phase. Crystallite size increased from 17.28 to 18.95 nm with longer thermal treatment times. Scanning Electron Microscopy revealed spherical and semi-spherical agglomerates with middle distribution of particle sizes ranging from 140 to 445 nm. The synthesized ZnO structures were evaluated as gas sensors for CO detection. Response time, recovery time, and sensor response were analyzed in a CO atmosphere at 100, 200, and 300 °C. The sample with thermal treatment for 13 h exhibited the lowest Tr of 2.43 s at a concentration of 166 parts per million and 300 °C. The Tr reduction correlated with a ZnO decrease particle size observed with longer thermal treatment times, highlighting the influence of particle size on sensor performance.
{"title":"Zinc oxide behavior in CO detection as a function of thermal treatment time","authors":"M P Munguía-Martín, D Sánchez-Campos, D Mendoza-Anaya, T V K Karthik, L S Villaseñor-Cerón, M I Reyes-Valderrama and V Rodríguez-Lugo","doi":"10.1088/2399-6528/ad777b","DOIUrl":"https://doi.org/10.1088/2399-6528/ad777b","url":null,"abstract":"Gas sensors are crucial for safety and well-being in various environments. Zinc oxide (ZnO) gas sensors are notable for their broad gas detection capabilities. In this study, ZnO structures were synthesized by optimized chemical precipitation method with urea, followed by a thermal treatment at 500 °C for 5, 10, 13, and 15 h. The microstructural, morphological, and CO sensing properties were examined. X-ray Diffraction analysis confirmed the hexagonal wurtzite phase. Crystallite size increased from 17.28 to 18.95 nm with longer thermal treatment times. Scanning Electron Microscopy revealed spherical and semi-spherical agglomerates with middle distribution of particle sizes ranging from 140 to 445 nm. The synthesized ZnO structures were evaluated as gas sensors for CO detection. Response time, recovery time, and sensor response were analyzed in a CO atmosphere at 100, 200, and 300 °C. The sample with thermal treatment for 13 h exhibited the lowest Tr of 2.43 s at a concentration of 166 parts per million and 300 °C. The Tr reduction correlated with a ZnO decrease particle size observed with longer thermal treatment times, highlighting the influence of particle size on sensor performance.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198672","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 : 2024-09-08DOI: 10.1088/2399-6528/ad74c6
Isiaka Aremua and Laure Gouba
In this paper, we study the exotic Landau problem at the classical level where two conserved quantities are derived. At the quantum level, the corresponding quantum operators of the conserved quantities provide two oscillator representations from which we derive two Boson Fock spaces. Using the normalized coherent states which are the minimum uncertainty states on noncommutative configuration space isomorphic to each of the boson Fock space, we form entangled coherent states which are Bell- like states labeled quasi-Bell states. The effect of non-maximality of a quasi-Bell state based quantum channel is investigated in the context of a teleportation of a qubit.
{"title":"Teleportation of a qubit using quasi-Bell states","authors":"Isiaka Aremua and Laure Gouba","doi":"10.1088/2399-6528/ad74c6","DOIUrl":"https://doi.org/10.1088/2399-6528/ad74c6","url":null,"abstract":"In this paper, we study the exotic Landau problem at the classical level where two conserved quantities are derived. At the quantum level, the corresponding quantum operators of the conserved quantities provide two oscillator representations from which we derive two Boson Fock spaces. Using the normalized coherent states which are the minimum uncertainty states on noncommutative configuration space isomorphic to each of the boson Fock space, we form entangled coherent states which are Bell- like states labeled quasi-Bell states. The effect of non-maximality of a quasi-Bell state based quantum channel is investigated in the context of a teleportation of a qubit.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198673","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 : 2024-08-27DOI: 10.1088/2399-6528/ad6f6b
Matteo Rosati
We compute the n-shot classical capacity of the quantum erasure channel, providing upper bounds and almost-matching lower bounds for it, the latter achievable via large-minimum-distance classical linear codes for any n. The protocols are in full product form, i.e. no entanglement is needed either at the encoder or decoder to attain the capacity, and they explicitly adapt to the transition between different error regimes as the erasure probability increases. Finally, we show that our upper and lower bounds on the capacity are tighter than those obtainable from the general theory of finite-size capacity via generalized divergences.
我们计算了量子擦除信道的 n 次经典容量，为其提供了上界和几乎匹配的下界，后者可通过任意 n 的大最小距离经典线性编码实现。这些协议是全积形式的，即编码器和解码器都不需要纠缠就能达到容量，而且随着擦除概率的增加，它们能明确地适应不同错误机制之间的转换。最后，我们证明了我们的容量上下限比通过广义发散从有限大小容量的一般理论中获得的容量上下限更严格。
{"title":"The n-shot classical capacity of the quantum erasure channel","authors":"Matteo Rosati","doi":"10.1088/2399-6528/ad6f6b","DOIUrl":"https://doi.org/10.1088/2399-6528/ad6f6b","url":null,"abstract":"We compute the <italic toggle=\"yes\">n</italic>-shot classical capacity of the quantum erasure channel, providing upper bounds and almost-matching lower bounds for it, the latter achievable via large-minimum-distance classical linear codes for any <italic toggle=\"yes\">n</italic>. The protocols are in full product form, i.e. no entanglement is needed either at the encoder or decoder to attain the capacity, and they explicitly adapt to the transition between different error regimes as the erasure probability increases. Finally, we show that our upper and lower bounds on the capacity are tighter than those obtainable from the general theory of finite-size capacity via generalized divergences.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198674","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 : 2024-08-27DOI: 10.1088/2399-6528/ad6e52
J E Vembe, M Førre
In the nonrelativistic and dipole regime of multiphoton ionization, spherical symmetry in all but the polarization direction of the laser pulse ensures that directional dependency in the photoelectron spectra is limited to the laser polarization direction, with the final distribution exhibiting no asymmetry along the propagation direction of the laser. When relativistic effects and spatial dependency in the external potential are accounted for however, the addition of time dilation and radiation pressure both impose anisotropic effects. Previously we have found that nondipole effects induce a redshift in the photoelectron energy distribution, while conversely relativistic effects induce a blueshift, with the net effect of an apparent near-cancellation of the two. In this work we study these effects further. By examining photoelectron momentum distributions acquired from simulations with the time-dependent Dirac equation we propose explanatory models for both phenomena and present a simplified model of the shifts as a function of the angle relative to the propagation direction of the laser pulse. It is found that both nondipole and relativistic effects must be accounted for on an equal footing in order to correctly describe the photoelectron momentum distribution in the high-intensity regime.
{"title":"Anisotropic effects in the nondipole relativistic photoionization of hydrogen","authors":"J E Vembe, M Førre","doi":"10.1088/2399-6528/ad6e52","DOIUrl":"https://doi.org/10.1088/2399-6528/ad6e52","url":null,"abstract":"In the nonrelativistic and dipole regime of multiphoton ionization, spherical symmetry in all but the polarization direction of the laser pulse ensures that directional dependency in the photoelectron spectra is limited to the laser polarization direction, with the final distribution exhibiting no asymmetry along the propagation direction of the laser. When relativistic effects and spatial dependency in the external potential are accounted for however, the addition of time dilation and radiation pressure both impose anisotropic effects. Previously we have found that nondipole effects induce a redshift in the photoelectron energy distribution, while conversely relativistic effects induce a blueshift, with the net effect of an apparent near-cancellation of the two. In this work we study these effects further. By examining photoelectron momentum distributions acquired from simulations with the time-dependent Dirac equation we propose explanatory models for both phenomena and present a simplified model of the shifts as a function of the angle relative to the propagation direction of the laser pulse. It is found that both nondipole and relativistic effects must be accounted for on an equal footing in order to correctly describe the photoelectron momentum distribution in the high-intensity regime.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198675","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 : 2024-08-14DOI: 10.1088/2399-6528/ad6ad1
R Rajaram, N Ritchey, B Castellani
A fundamental challenge in the study of probability distributions is the quantification of inequality that is inherently present in them. Some parts of the distribution are more probable and some others are not, and we are interested in the quantification of this inequality through the lens of mathematical diversity, which is a new approach to studying inequality. We offer a theoretical advance, based on case-based entropy and slope of diversity, which addresses inequality for arbitrary probability distributions through the concept of mathematical diversity. Our approach is useful in three important ways: (1) it offers a universal way to measure inequality in arbitrary probability distributions based purely on the entropic uncertainty that is inherent in them and nothing else; (2) it allows us to compare the degree of inequality of arbitrary parts of any distribution (not just tails) and entire distributions alike; and (3) it can glean out empirical rules similar to the 80/20 rule, not just for the power law but for any given distribution or its parts thereof. The techniques shown in this paper demonstrate a more general machinery to quantify inequality, compare the degree of inequality of parts or whole of general distributions, and prove or glean out empirical rules for general distributions based on mathematical diversity. We demonstrate the utility of this new machinery by applying it to the power law, the exponential and the geometric distributions. The 60 − 40 rule of restricted diversity states that 60 percent or more of cases following a power law (or more generally a right skewed distribution) reside within 40 percent or less of the lower bound of Shannon equivalent equi-probable (SEE) types as measured by case-based entropy. In this paper, we prove the 60 − 40 rule for power law distributions analytically. We also show that in all power law distributions, the second half of the distribution is at least 4 times more uniformly distributed as the first. Lastly, we also show a scale-free way of comparing probability distributions based on the idea of mathematical diversity of parts of a distribution. We use this comparison technique to compare the exponential and power law distribution, and obtain the exponential distribution as an entropic limit of the power law distribution. We also demonstrate that the machinery is applicable to discrete distributions by proving a general result regarding the comparison of parts of the geometric distribution.
{"title":"On the mathematical quantification of inequality in probability distributions","authors":"R Rajaram, N Ritchey, B Castellani","doi":"10.1088/2399-6528/ad6ad1","DOIUrl":"https://doi.org/10.1088/2399-6528/ad6ad1","url":null,"abstract":"A fundamental challenge in the study of probability distributions is the quantification of inequality that is inherently present in them. Some parts of the distribution are more probable and some others are not, and we are interested in the quantification of this inequality through the lens of mathematical diversity, which is a new approach to studying inequality. We offer a theoretical advance, based on case-based entropy and slope of diversity, which addresses inequality for arbitrary probability distributions through the concept of mathematical diversity. Our approach is useful in three important ways: (1) it offers a universal way to measure inequality in arbitrary probability distributions based purely on the entropic uncertainty that is inherent in them and nothing else; (2) it allows us to compare the degree of inequality of arbitrary parts of any distribution (not just tails) and entire distributions alike; and (3) it can glean out empirical rules similar to the 80/20 rule, not just for the power law but for any given distribution or its parts thereof. The techniques shown in this paper demonstrate a more general machinery to quantify inequality, compare the degree of inequality of parts or whole of general distributions, and prove or glean out empirical rules for general distributions based on mathematical diversity. We demonstrate the utility of this new machinery by applying it to the power law, the exponential and the geometric distributions. The 60 − 40 rule of restricted diversity states that 60 percent or more of cases following a power law (or more generally a right skewed distribution) reside within 40 percent or less of the lower bound of Shannon equivalent equi-probable (SEE) types as measured by case-based entropy. In this paper, we prove the 60 − 40 rule for power law distributions analytically. We also show that in all power law distributions, the second half of the distribution is at least 4 times more uniformly distributed as the first. Lastly, we also show a scale-free way of comparing probability distributions based on the idea of mathematical diversity of parts of a distribution. We use this comparison technique to compare the exponential and power law distribution, and obtain the exponential distribution as an entropic limit of the power law distribution. We also demonstrate that the machinery is applicable to discrete distributions by proving a general result regarding the comparison of parts of the geometric distribution.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198750","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 : 2024-08-09DOI: 10.1088/2399-6528/ad6db7
Andrea Ceschini, A. Rosato, Massimo Panella
Quantum Recurrent Neural Networks are receiving an increased attention thanks to their enhanced generalization capabilities in time series analysis. However, their performances were bottlenecked by long training times and unscalable architectures. In this paper, we propose a novel Quantum Recurrent Neural Network model based on Quantum Gated Recurrent Units. It uses a learnable Variational Quantum Layer to process temporal data, interspersed with two classical layers to properly match the dimensionality of the input and output vectors. Such an architecture has fewer quantum parameters than existing Quantum Long Short-Term Memory models. Both the quantum networks were evaluated on periodic and real-world time series datasets, together with the classical counterparts. The quantum models exhibited superior performances compared to the classical ones in all the test cases. The Quantum Gated Recurrent Units outperformed the Quantum Long Short-Term Memory network despite having a simpler internal configuration. Moreover, the Quantum Gated Recurrent Units network demonstrated to be about 25% faster during the training and inference procedure over the Quantum Long Short-Term Memory. This improvement in speed comes with one less quantum circuit to be executed, suggesting that our model may offer a more efficient alternative for implementing Quantum Recurrent Neural Networks on both simulated and real quantum hardware.
{"title":"A Variational Approach to Quantum Gated Recurrent Units","authors":"Andrea Ceschini, A. Rosato, Massimo Panella","doi":"10.1088/2399-6528/ad6db7","DOIUrl":"https://doi.org/10.1088/2399-6528/ad6db7","url":null,"abstract":"\u0000 Quantum Recurrent Neural Networks are receiving an increased attention thanks to their enhanced generalization capabilities in time series analysis. However, their performances were bottlenecked by long training times and unscalable architectures. In this paper, we propose a novel Quantum Recurrent Neural Network model based on Quantum Gated Recurrent Units. It uses a learnable Variational Quantum Layer to process temporal data, interspersed with two classical layers to properly match the dimensionality of the input and output vectors. Such an architecture has fewer quantum parameters than existing Quantum Long Short-Term Memory models. Both the quantum networks were evaluated on periodic and real-world time series datasets, together with the classical counterparts. The quantum models exhibited superior performances compared to the classical ones in all the test cases. The Quantum Gated Recurrent Units outperformed the Quantum Long Short-Term Memory network despite having a simpler internal configuration. Moreover, the Quantum Gated Recurrent Units network demonstrated to be about 25% faster during the training and inference procedure over the Quantum Long Short-Term Memory. This improvement in speed comes with one less quantum circuit to be executed, suggesting that our model may offer a more efficient alternative for implementing Quantum Recurrent Neural Networks on both simulated and real quantum hardware.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141921515","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 : 2024-08-09DOI: 10.1088/2399-6528/ad6db8
Archana C M, Bhaskar Awadhiya, Yashwanth Nanjappa
This paper investigates the ferroelectric-dielectric heterostructure with a fixed dielectric oxide and different ferroelectric oxides. This study is focused on the enhancement of capacitance, voltage amplification, and negative capacitance stabilization. In the first section of this study, an isolated ferroelectric capacitor with intrinsically unstable negative capacitance is examined for different ferroelectric oxides. To address the concern of instability a dielectric oxide is added in series to the ferroelectric capacitors. This addition raises the heterostructure's total capacitance while stabilizing the negative capacitance. Silicon (Si), Zirconium (Zr), Aluminum (Al), and Strontium (Sr) doped hafnium oxide are used in heterostructure. It is found that the capacitance of Sr doped hafnium oxide is closely matched with the dielectric capacitance, therefore it provides the highest voltage amplification and enhanced capacitance among the other ferroelectric oxide considered.
{"title":"Comparative Investigation of Passive Voltage Amplification in Ferroelectric-Dielectric Heterostructure","authors":"Archana C M, Bhaskar Awadhiya, Yashwanth Nanjappa","doi":"10.1088/2399-6528/ad6db8","DOIUrl":"https://doi.org/10.1088/2399-6528/ad6db8","url":null,"abstract":"\u0000 This paper investigates the ferroelectric-dielectric heterostructure with a fixed dielectric oxide and different ferroelectric oxides. This study is focused on the enhancement of capacitance, voltage amplification, and negative capacitance stabilization. In the first section of this study, an isolated ferroelectric capacitor with intrinsically unstable negative capacitance is examined for different ferroelectric oxides. To address the concern of instability a dielectric oxide is added in series to the ferroelectric capacitors. This addition raises the heterostructure's total capacitance while stabilizing the negative capacitance. Silicon (Si), Zirconium (Zr), Aluminum (Al), and Strontium (Sr) doped hafnium oxide are used in heterostructure. It is found that the capacitance of Sr doped hafnium oxide is closely matched with the dielectric capacitance, therefore it provides the highest voltage amplification and enhanced capacitance among the other ferroelectric oxide considered.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141924968","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 : 2024-07-24DOI: 10.1088/2399-6528/ad61bb
Andrzej Janutka
Spontaneous evolutions of domains in magnetic nanowires and of magnetic bubbles in open ferromagnetic nanolayers are investigated using micromagnetic simulations. We compare temperature dependent dynamics of domain wall (DW) systems in Permalloy (Py) nanowires and systems of chiral DWs in ultra-thin nanowires with perpendicular magnetic anisotropy (PMA) and Dzyaloshinskii-Moriya interaction (DMI). In Py nanowires DWs collide and, in majority of cases, the collision leads to the DW annihilation in disagreement with the expectation of topological protection of sums of all the magnetic charges attached to the nanowire edges which are carried by DWs. For our purpose of discussing the DW collision in the presence of thermal excitations, we revisit the problem of field-driven collisions of DWs in Py nanowires at zero temperature. We claim that thermal fluctuations can counteract the collision-induced annihilation of DWs, thought further improvement of stabilization of domain structures is achievable via structurization of the magnetic nanowires (dividing them into grains). In PMA-DMI nanowires, thermally-excited chiral DWs can be randomly approaching or moving away while not being annihilated. A problem related to the motion of chiral DWs is the spontaneous motion of magnetic bubbles in open PMA-DMI planes. The magnetic bubbles expand or shrink to vanishing dependent on strength of the DMI interaction. Such a motion appears to be be strongly influenced by temperature and by structural discontinuities of the magnetic layer.
{"title":"Temperature and medium structurization effect on spontaneous evolution of domains and bubbles in magnetic nanostructures","authors":"Andrzej Janutka","doi":"10.1088/2399-6528/ad61bb","DOIUrl":"https://doi.org/10.1088/2399-6528/ad61bb","url":null,"abstract":"Spontaneous evolutions of domains in magnetic nanowires and of magnetic bubbles in open ferromagnetic nanolayers are investigated using micromagnetic simulations. We compare temperature dependent dynamics of domain wall (DW) systems in Permalloy (Py) nanowires and systems of chiral DWs in ultra-thin nanowires with perpendicular magnetic anisotropy (PMA) and Dzyaloshinskii-Moriya interaction (DMI). In Py nanowires DWs collide and, in majority of cases, the collision leads to the DW annihilation in disagreement with the expectation of topological protection of sums of all the magnetic charges attached to the nanowire edges which are carried by DWs. For our purpose of discussing the DW collision in the presence of thermal excitations, we revisit the problem of field-driven collisions of DWs in Py nanowires at zero temperature. We claim that thermal fluctuations can counteract the collision-induced annihilation of DWs, thought further improvement of stabilization of domain structures is achievable via structurization of the magnetic nanowires (dividing them into grains). In PMA-DMI nanowires, thermally-excited chiral DWs can be randomly approaching or moving away while not being annihilated. A problem related to the motion of chiral DWs is the spontaneous motion of magnetic bubbles in open PMA-DMI planes. The magnetic bubbles expand or shrink to vanishing dependent on strength of the DMI interaction. Such a motion appears to be be strongly influenced by temperature and by structural discontinuities of the magnetic layer.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141778041","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 : 2024-07-23DOI: 10.1088/2399-6528/ad66ac
Muhammad Javed Iqbal, Inayatullah Soomro, Mumtaz Hussain Mahar
Soft materials, including diblock copolymers, are advancing nanotechnology due to their unique properties, applications materials include energy harvesting, water sanitation, environmental treatment, nanosensors, drug delivery and nanolithography. These materials are light, cheap, efficient, sensitive, durable and more functional, whose new morphologies have been predicted by mathematicians through simulation. This work produces and predicts the pattern of packing of nano-cylinders by using confinement to appreciate the frustration in the packing of nano-cylinders under the influence of curvature. In this contribution, the cell dynamic simulations model is used to examine the impact of circular annular pore confinement on system orientation toward cylindrical morphologies. A 9-point stencil approximates the isotropic Laplacian by finite-difference discretization on a polar grid to meet the requirement of a cell dynamic simulation model. FORTRAN codes are generated for the set of PDEs included in the CDS model. OPEN DX is used to visualise the predicted cylindrical patterns. The consistency of our results with experimental observations makes our research valid and significant.
{"title":"Re-patterning of cylindrical packing of diblock copolymers under confinement and curvature effects by using approximations of PDE’s involved in the CDS model on polar mesh system","authors":"Muhammad Javed Iqbal, Inayatullah Soomro, Mumtaz Hussain Mahar","doi":"10.1088/2399-6528/ad66ac","DOIUrl":"https://doi.org/10.1088/2399-6528/ad66ac","url":null,"abstract":"\u0000 Soft materials, including diblock copolymers, are advancing nanotechnology due to their unique properties, applications materials include energy harvesting, water sanitation, environmental treatment, nanosensors, drug delivery and nanolithography. These materials are light, cheap, efficient, sensitive, durable and more functional, whose new morphologies have been predicted by mathematicians through simulation. This work produces and predicts the pattern of packing of nano-cylinders by using confinement to appreciate the frustration in the packing of nano-cylinders under the influence of curvature. In this contribution, the cell dynamic simulations model is used to examine the impact of circular annular pore confinement on system orientation toward cylindrical morphologies. A 9-point stencil approximates the isotropic Laplacian by finite-difference discretization on a polar grid to meet the requirement of a cell dynamic simulation model. FORTRAN codes are generated for the set of PDEs included in the CDS model. OPEN DX is used to visualise the predicted cylindrical patterns. The consistency of our results with experimental observations makes our research valid and significant.","PeriodicalId":47089,"journal":{"name":"Journal of Physics Communications","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141810716","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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