Pub Date : 2024-04-25DOI: 10.1088/1361-6463/ad4371
Naresh kumar Reddy Andra, V. V. Kim, Victor Kӓrcher, Helmut Zacharias, A. Bundulis, A. Sarakovskis, A. Atvars, A. Ubelis, R. A. Ganeev
We demonstrate the generation of the low- and high-order harmonic vortex beams from a single spiral phase plate (SPP) illuminated by different laser wavelengths. The second harmonic (532 nm) originates from the application of the wavefront-structured 1064 nm femtosecond pulses with fractional orbital angular momentum during propagation through a lithium triborate crystal, while the third harmonic (500 nm) originates from the application of the wavefront-structured near-IR (1500 nm) femtosecond pulses with integer orbital angular momentum during propagation through a 150 µm thick fused silica plate. The topological charges of the second and third harmonics are measured and compared. The increase in topological charge and the peculiarities in orbital angular momentum variations during modification of the polarisation of the incident radiation are analyzed and discussed. The two-color-pump-driven second-harmonic vortex radiation interacted with an Ar gas jet to generate vortex harmonics up to the 14th order with double-lobe complex spatial profiles in the extreme ultraviolet region.
{"title":"Spatial shaping of low-and high-order harmonics generated using vortex beams","authors":"Naresh kumar Reddy Andra, V. V. Kim, Victor Kӓrcher, Helmut Zacharias, A. Bundulis, A. Sarakovskis, A. Atvars, A. Ubelis, R. A. Ganeev","doi":"10.1088/1361-6463/ad4371","DOIUrl":"https://doi.org/10.1088/1361-6463/ad4371","url":null,"abstract":"\u0000 We demonstrate the generation of the low- and high-order harmonic vortex beams from a single spiral phase plate (SPP) illuminated by different laser wavelengths. The second harmonic (532 nm) originates from the application of the wavefront-structured 1064 nm femtosecond pulses with fractional orbital angular momentum during propagation through a lithium triborate crystal, while the third harmonic (500 nm) originates from the application of the wavefront-structured near-IR (1500 nm) femtosecond pulses with integer orbital angular momentum during propagation through a 150 µm thick fused silica plate. The topological charges of the second and third harmonics are measured and compared. The increase in topological charge and the peculiarities in orbital angular momentum variations during modification of the polarisation of the incident radiation are analyzed and discussed. The two-color-pump-driven second-harmonic vortex radiation interacted with an Ar gas jet to generate vortex harmonics up to the 14th order with double-lobe complex spatial profiles in the extreme ultraviolet region.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"74 15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140655337","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}
Phase change cooling technology offers high cooling efficiency, safety, and reliability, representing a novel approach to achieving efficient heat dissipation for high-power and large-capacity electrical equipment. The formulation of the cooling medium is pivotal to phase change cooling technology. However, current media exhibit compatibility, stability, economy, and environmental friendliness deficiencies. Consideration could be given to implementing the C6F12O medium due to its superior overall performance and ability to meet the latent heat requirements in phase change cooling equipment. This paper employs a numerical simulation approach that combines the phase field method based on the Cahn-Hilliard equation with the theory of electrohydrodynamics. It investigates the impact of temperature, electric field intensity, and electric field direction on the evolution of bubble motion and the boiling state of the C6F12O medium, considering the interaction of electric-fluid-heat-phase fields. Numerical results indicate that the system undergoes initial nucleate boiling, nucleate boiling, and film boiling stages at T=330~335 K, T=335~350 K, and T≥355 K, respectively. The introduction of an appropriate electric field can enhance the motion evolution of C6F12O bubbles. However, attention must be paid to the formation of bubble channels under high field strength to prevent potential decreases in insulation performance. An inhomogeneous electric field in the vertical direction proves more effective in improving the bubble release rate compared to a uniform electric field. To some extent, an inhomogeneous electric field in the horizontal direction can prevent the mass accumulation of bubbles in regions of high field intensity. This research has the potential to offer theoretical guidance for the engineering application of the C6F12O phase change cooling medium.
相变冷却技术具有冷却效率高、安全可靠等特点，是实现大功率、大容量电气设备高效散热的一种新方法。冷却介质的配方对相变冷却技术至关重要。然而，目前的介质在兼容性、稳定性、经济性和环保性方面都存在不足。C6F12O 介质具有优异的综合性能，能够满足相变冷却设备的潜热要求，因此可以考虑采用这种介质。本文采用了一种数值模拟方法，将基于卡恩-希利亚德方程的相场方法与电流体力学理论相结合。考虑到电-流体-热-相场的相互作用，研究了温度、电场强度和电场方向对 C6F12O 介质气泡运动和沸腾状态演变的影响。数值结果表明，在 T=330~335 K、T=335~350 K 和 T≥355 K 时，体系分别经历了初始核沸腾、核沸腾和膜沸腾阶段。引入适当的电场可以增强 C6F12O 气泡的运动演化。但是，必须注意高电场强度下气泡通道的形成，以防止绝缘性能的潜在下降。与均匀电场相比，垂直方向的不均匀电场在提高气泡释放率方面更为有效。在某种程度上，水平方向的不均匀电场可以防止气泡在高场强区域大量积聚。这项研究有望为 C6F12O 相变冷却介质的工程应用提供理论指导。
{"title":"Numerical Simulation of Electric Field-Induced Phase Transition Evolution and Boiling Characteristics in the Evaporative Cooling Medium C6F12O","authors":"Shuangshuang Tian, Jiahao Wang, Yingyu Wu, Feng Hu, Yongchao Luo, Chaohai Zhang, Shen Gao, Zian Yuan","doi":"10.1088/1361-6463/ad436a","DOIUrl":"https://doi.org/10.1088/1361-6463/ad436a","url":null,"abstract":"\u0000 Phase change cooling technology offers high cooling efficiency, safety, and reliability, representing a novel approach to achieving efficient heat dissipation for high-power and large-capacity electrical equipment. The formulation of the cooling medium is pivotal to phase change cooling technology. However, current media exhibit compatibility, stability, economy, and environmental friendliness deficiencies. Consideration could be given to implementing the C6F12O medium due to its superior overall performance and ability to meet the latent heat requirements in phase change cooling equipment. This paper employs a numerical simulation approach that combines the phase field method based on the Cahn-Hilliard equation with the theory of electrohydrodynamics. It investigates the impact of temperature, electric field intensity, and electric field direction on the evolution of bubble motion and the boiling state of the C6F12O medium, considering the interaction of electric-fluid-heat-phase fields. Numerical results indicate that the system undergoes initial nucleate boiling, nucleate boiling, and film boiling stages at T=330~335 K, T=335~350 K, and T≥355 K, respectively. The introduction of an appropriate electric field can enhance the motion evolution of C6F12O bubbles. However, attention must be paid to the formation of bubble channels under high field strength to prevent potential decreases in insulation performance. An inhomogeneous electric field in the vertical direction proves more effective in improving the bubble release rate compared to a uniform electric field. To some extent, an inhomogeneous electric field in the horizontal direction can prevent the mass accumulation of bubbles in regions of high field intensity. This research has the potential to offer theoretical guidance for the engineering application of the C6F12O phase change cooling medium.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"58 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140655785","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 : 2024-04-24DOI: 10.1088/1361-6463/ad42aa
Brahmaranjan Panigrahi, M. M. Raja, Chandrasekhar Murapaka, A. Haldar
Microwave devices with more than one operating frequency and their ease of tunability are of great importance for high-frequency information processing. Magnetic thin films offer an unparalleled advantage of engineering different microwave bands that can be precisely tailored and reconfigured externally. Here, novel trilayer structures consisting of NiFe/FeMn/NiFe with varying anti-ferromagnetic FeMn layer thickness have been investigated by exploring their ferromagnetic resonance (FMR) properties and inverse spin Hall effect (ISHE) responses. Two-step magnetic hysteresis loops are observed for higher FeMn thickness (t ≥ 12 nm), where the bottom NiFe layer shows a comparatively more significant shift due to the presence of strong interfacial exchange coupling. FMR study reveales two resonant modes associated with the two ferromagnetic layers, which are distinguishable for higher thicknesses of FeMn or at high excitation frequencies. The choice of FeMn thickness determines the operating frequencies, which can be finely tailored by optimizing the FeMn thickness. Gilbert damping parameter is found to be in the range of 0.009 - 0.012 where the presence of exchange bias adds to the the scattering mechanisms. Prominent ISHE responses are obtained from the bottom NiFe layer as compared to the top NiFe layer. Variation of FeMn thickness also shows a strong influence on the spin pumping (Vsp), and perpendicular anisotropic magnetoresistance (VAMR⊥) components. The results are correlated with the efficiency of spin flow and spin-to-charge conversion of the FeMn layer. Our systems can be used as an emerging alternative for microwave detectors and microwave energy harvesters.
{"title":"Dual mode spin to charge conversion using inverse spin Hall effect in NiFe/FeMn/NiFe multilayer thin films","authors":"Brahmaranjan Panigrahi, M. M. Raja, Chandrasekhar Murapaka, A. Haldar","doi":"10.1088/1361-6463/ad42aa","DOIUrl":"https://doi.org/10.1088/1361-6463/ad42aa","url":null,"abstract":"\u0000 Microwave devices with more than one operating frequency and their ease of tunability are of great importance for high-frequency information processing. Magnetic thin films offer an unparalleled advantage of engineering different microwave bands that can be precisely tailored and reconfigured externally. Here, novel trilayer structures consisting of NiFe/FeMn/NiFe with varying anti-ferromagnetic FeMn layer thickness have been investigated by exploring their ferromagnetic resonance (FMR) properties and inverse spin Hall effect (ISHE) responses. Two-step magnetic hysteresis loops are observed for higher FeMn thickness (t ≥ 12 nm), where the bottom NiFe layer shows a comparatively more significant shift due to the presence of strong interfacial exchange coupling. FMR study reveales two resonant modes associated with the two ferromagnetic layers, which are distinguishable for higher thicknesses of FeMn or at high excitation frequencies. The choice of FeMn thickness determines the operating frequencies, which can be finely tailored by optimizing the FeMn thickness. Gilbert damping parameter is found to be in the range of 0.009 - 0.012 where the presence of exchange bias adds to the the scattering mechanisms. Prominent ISHE responses are obtained from the bottom NiFe layer as compared to the top NiFe layer. Variation of FeMn thickness also shows a strong influence on the spin pumping (Vsp), and perpendicular anisotropic magnetoresistance (VAMR⊥) components. The results are correlated with the efficiency of spin flow and spin-to-charge conversion of the FeMn layer. Our systems can be used as an emerging alternative for microwave detectors and microwave energy harvesters.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"16 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140660124","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 : 2024-04-24DOI: 10.1088/1361-6463/ad42a8
Aykut Turfanda, H. Ünlü
We propose a model to depict the endurance test results of a resistive switching device with vertically oriented layers of nanocrystalline transition metal dichalcogenide layers with respect to the substrate. We aim to relate and understand the endurance test results in the literature with our model, which is tested using density functional theory simulations. We conclude a relation between endurance test results and skin effect dominated alternating electric current resistance and surface resistance. These results are important to manipulate and understand the reliability and accuracy of cycle-to-cycle variations in the endurance test results.
{"title":"Cycle-to-cycle Switching Endurance Variability in Vertically Aligned Nanocrystalline Molybdenum Disulfide: Computational Insights","authors":"Aykut Turfanda, H. Ünlü","doi":"10.1088/1361-6463/ad42a8","DOIUrl":"https://doi.org/10.1088/1361-6463/ad42a8","url":null,"abstract":"\u0000 We propose a model to depict the endurance test results of a resistive switching device with vertically oriented layers of nanocrystalline transition metal dichalcogenide layers with respect to the substrate. We aim to relate and understand the endurance test results in the literature with our model, which is tested using density functional theory simulations. We conclude a relation between endurance test results and skin effect dominated alternating electric current resistance and surface resistance. These results are important to manipulate and understand the reliability and accuracy of cycle-to-cycle variations in the endurance test results.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"60 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140664913","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 : 2024-04-24DOI: 10.1088/1361-6463/ad42ab
Siyi Xu, Danyi Li, Wenrui Wang, Lin Lin, Ying Sun, Jihao吉豪 Li李, Linfan Li
A large amount of toxic smoke and heat generated by the combustion of ethylene vinyl acetate copolymer (EVA) poses a significant threat to human fire escape evacuation. This work aims to use γ-ray to prepare e-MXene@Ag hybrid flame-retardant materials by the method of in-situ reduction, and EVA composites are prepared by melt blending to reduce the smoke and toxic gases produced during combustion significantly. Compared with pure EVA, the total heat release, total smoke release, and the production rate of CO and CO2 produced by the combustion of EVA composite with 1wt% e-MXene@Ag1.0 decreased by 30.3%, 33.3%, 18.2%, and 20.1% respectively, while the content of residue increased by 907.4%. The fire hazard reduction of EVA composite materials was due to the physical barrier, catalytic carbonization and adsorption of the e-MXene@Ag1.0 hybrid. In addition, e-MXene@Ag1.0 can also further increase the mechanical properties of EVA composites due to its own "multi-contact point limit structure."
乙烯-醋酸乙烯共聚物（EVA）燃烧产生的大量有毒烟雾和热量对人类火场逃生疏散构成了极大威胁。本研究旨在利用γ射线原位还原法制备e-MXene@Ag杂化阻燃材料，通过熔融共混制备EVA复合材料，大幅降低燃烧过程中产生的烟气和有毒气体。与纯 EVA 相比，含 1wt% e-MXene@Ag1.0 的 EVA 复合材料燃烧时产生的总放热量、总放烟量、CO 和 CO2 的产生率分别降低了 30.3%、33.3%、18.2% 和 20.1%，而残渣含量增加了 907.4%。EVA 复合材料火灾危险性的降低得益于 e-MXene@Ag1.0 混合物的物理阻隔、催化碳化和吸附作用。此外，由于其自身的 "多接触点极限结构"，e-MXene@Ag1.0 还能进一步提高 EVA 复合材料的机械性能。
{"title":"In situ growth of Ag nanoparticles on the surface of MXene by γ-ray irradiation to fabricate EVA composite: The improvement of flame retardancy, smoke suppression, and mechanical properties","authors":"Siyi Xu, Danyi Li, Wenrui Wang, Lin Lin, Ying Sun, Jihao吉豪 Li李, Linfan Li","doi":"10.1088/1361-6463/ad42ab","DOIUrl":"https://doi.org/10.1088/1361-6463/ad42ab","url":null,"abstract":"\u0000 A large amount of toxic smoke and heat generated by the combustion of ethylene vinyl acetate copolymer (EVA) poses a significant threat to human fire escape evacuation. This work aims to use γ-ray to prepare e-MXene@Ag hybrid flame-retardant materials by the method of in-situ reduction, and EVA composites are prepared by melt blending to reduce the smoke and toxic gases produced during combustion significantly. Compared with pure EVA, the total heat release, total smoke release, and the production rate of CO and CO2 produced by the combustion of EVA composite with 1wt% e-MXene@Ag1.0 decreased by 30.3%, 33.3%, 18.2%, and 20.1% respectively, while the content of residue increased by 907.4%. The fire hazard reduction of EVA composite materials was due to the physical barrier, catalytic carbonization and adsorption of the e-MXene@Ag1.0 hybrid. In addition, e-MXene@Ag1.0 can also further increase the mechanical properties of EVA composites due to its own \"multi-contact point limit structure.\"","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"45 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140660006","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 : 2024-04-22DOI: 10.1088/1361-6463/ad4163
Fang-Jie Zhou, Yu-Ru Zhang, Kai Zhao, D. Wen, You-Nian Wang
The higher harmonics generated by nonlinear sheath motion would enhance the standing wave effect, and thus lead to center-peaked plasma density profile in very-high-frequency (VHF) capacitive discharges. In this work, a nonlinear transmission line (NTL) model introduced in [Zhou et al. Plasma Sources Sci. Technol. 30 125017 (2021)] has been extended, with radial transport of various particles and nonlinear sheath motion into account, to investigate the effects of CF4 fraction α on the nonlinear standing wave excitation and plasma radial uniformity in VHF (60 MHz) capacitively coupled Ar/CF4 plasmas at 3 Pa. The results indicate that for pure Ar discharges (i.e. α=0%), the nonlinearly excited harmonics with short wavelength significantly enhance the electron power absorption at the radial center, resulting in a pronounced central-high plasma density profile. As α increases, the high-order harmonics are gradually damped due to the increase of resistance, as well as the longer wavelength caused by thicker sheath thickness. Thus, the radial profile of the electron absorbed power density shifts from center-peak to edge-high. Besides, at the radial center, the electron density and Ar+ ion density decrease with α, CF3+ ion density shows an increasing trend, while F- ion density initially rises and then decreases. Moreover, the density profiles of all the species become more uniform at higher α, due to the suppressed nonlinear standing wave excitation and the longer wavelength of the nonlinear harmonics.
{"title":"Role of gas composition in weakened nonlinear standing wave excitation and improved plasma radial uniformity in very-high-frequency asymmetric capacitive Ar/CF4 discharges","authors":"Fang-Jie Zhou, Yu-Ru Zhang, Kai Zhao, D. Wen, You-Nian Wang","doi":"10.1088/1361-6463/ad4163","DOIUrl":"https://doi.org/10.1088/1361-6463/ad4163","url":null,"abstract":"\u0000 The higher harmonics generated by nonlinear sheath motion would enhance the standing wave effect, and thus lead to center-peaked plasma density profile in very-high-frequency (VHF) capacitive discharges. In this work, a nonlinear transmission line (NTL) model introduced in [Zhou et al. Plasma Sources Sci. Technol. 30 125017 (2021)] has been extended, with radial transport of various particles and nonlinear sheath motion into account, to investigate the effects of CF4 fraction α on the nonlinear standing wave excitation and plasma radial uniformity in VHF (60 MHz) capacitively coupled Ar/CF4 plasmas at 3 Pa. The results indicate that for pure Ar discharges (i.e. α=0%), the nonlinearly excited harmonics with short wavelength significantly enhance the electron power absorption at the radial center, resulting in a pronounced central-high plasma density profile. As α increases, the high-order harmonics are gradually damped due to the increase of resistance, as well as the longer wavelength caused by thicker sheath thickness. Thus, the radial profile of the electron absorbed power density shifts from center-peak to edge-high. Besides, at the radial center, the electron density and Ar+ ion density decrease with α, CF3+ ion density shows an increasing trend, while F- ion density initially rises and then decreases. Moreover, the density profiles of all the species become more uniform at higher α, due to the suppressed nonlinear standing wave excitation and the longer wavelength of the nonlinear harmonics.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"12 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140673438","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 : 2024-04-22DOI: 10.1088/1361-6463/ad4162
Jiabin Shi, Haibao Lu, Tengfei Zheng, Yong-Qing Fu
Water-triggered shape memory polymers (SMPs) have been extensively studied for biomedical applications due to their advantages of non-thermal actuation capability. However, few studies have been carried out to explore the working principle of shape recovery onset, which is essentially determined by the complex reactions between polymer macromolecules and water molecules. In this study, we developed a phase separation model to describe the dynamic glass transition in water-triggered SMPs. Based on the phase transition theory, dense and dilute phase separations of polymer macromolecules can be achieved when the dynamic diffusions of water molecules in the SMPs undergo dehydration and absorption processes, respectively. Then, the dynamic glass transition is resulted from the dehydration and absorption of water molecules, leading to the dense and dilute phases in the SMPs. Therefore, a free-energy equation has been developed to characterize the recovery onset, in which the mixing free energy and elastic free energy are originated from the Flory-Huggins solution theory and phase separation model, respectively. Moreover, the glass transition and its connection to shape recovery behaviors, i.e., recovery ratio, relaxation time and dynamic mechanical modulus, have also been investigated, according to the Fick’s diffusion law. Meanwhile, onset of programmable recovery has been explained by the dynamic phase separation, based on the transpiration theory and permeability model. Finally, the proposed model is verified using the experimental results reported in the literature. This study is expected to provide a fundamental approach to formulate the constitutive relationship between the dynamic phase separation and programmable recovery onset in the water-triggered SMPs.
{"title":"A dynamic phase separation model for glass transition behavior in water-triggered shape memory polymer towards programmable recovery onset","authors":"Jiabin Shi, Haibao Lu, Tengfei Zheng, Yong-Qing Fu","doi":"10.1088/1361-6463/ad4162","DOIUrl":"https://doi.org/10.1088/1361-6463/ad4162","url":null,"abstract":"\u0000 Water-triggered shape memory polymers (SMPs) have been extensively studied for biomedical applications due to their advantages of non-thermal actuation capability. However, few studies have been carried out to explore the working principle of shape recovery onset, which is essentially determined by the complex reactions between polymer macromolecules and water molecules. In this study, we developed a phase separation model to describe the dynamic glass transition in water-triggered SMPs. Based on the phase transition theory, dense and dilute phase separations of polymer macromolecules can be achieved when the dynamic diffusions of water molecules in the SMPs undergo dehydration and absorption processes, respectively. Then, the dynamic glass transition is resulted from the dehydration and absorption of water molecules, leading to the dense and dilute phases in the SMPs. Therefore, a free-energy equation has been developed to characterize the recovery onset, in which the mixing free energy and elastic free energy are originated from the Flory-Huggins solution theory and phase separation model, respectively. Moreover, the glass transition and its connection to shape recovery behaviors, i.e., recovery ratio, relaxation time and dynamic mechanical modulus, have also been investigated, according to the Fick’s diffusion law. Meanwhile, onset of programmable recovery has been explained by the dynamic phase separation, based on the transpiration theory and permeability model. Finally, the proposed model is verified using the experimental results reported in the literature. This study is expected to provide a fundamental approach to formulate the constitutive relationship between the dynamic phase separation and programmable recovery onset in the water-triggered SMPs.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"67 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140675525","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 : 2024-04-22DOI: 10.1088/1361-6463/ad4159
Geetanjali Jena, Gopal Kulkarni, Ravi Varshney, Dibakar Roy Chowdhury
Recently, topological ring resonators (TRRs) have emerged as a burgeoning platform for exploring the topological aspects of photonic systems and resonator dynamics. Integrating topology into cavity dynamics offers a new paradigm to unveil various fascinating phenomena, including backscattering immune wave propagation, unidirectional transmission, and reflection-free energy transport. With this background, we provide a scheme to achieve robust high Q resonances in a metal-based topological photonic crystal (TPC) exhibiting defect-immune spectral characteristics in the microwave frequency regime. Coupled with a ring resonator, our proposed topological platform demonstrates the excitation of high Q resonances in the range 230-540. Except for the resonances, a robust microwave transmission (~0 dB) is observed in the investigated frequency regime 7.1-7.6 GHz, depicting a minimal scattering loss even around the sharp corners of the ring resonator. Further, the topological robustness of the propagating microwave and the excited resonances are examined by introducing an external Si obstacle at the domain interface. Our study reveals a minimal transmission loss (<7 dB) and negligible perturbation (<8%) in the Q factors when the Si barrier placed towards the input end of the straight topological waveguide. In addition, we have also demonstrated a novel way of exciting new resonances in the ring resonator that holds considerable promise for designing a TRR-based all-pass notch filter in the microwave regime.
{"title":"External Defect Immune High Quality Resonances in Microwave Topological Ring Resonator","authors":"Geetanjali Jena, Gopal Kulkarni, Ravi Varshney, Dibakar Roy Chowdhury","doi":"10.1088/1361-6463/ad4159","DOIUrl":"https://doi.org/10.1088/1361-6463/ad4159","url":null,"abstract":"\u0000 Recently, topological ring resonators (TRRs) have emerged as a burgeoning platform for exploring the topological aspects of photonic systems and resonator dynamics. Integrating topology into cavity dynamics offers a new paradigm to unveil various fascinating phenomena, including backscattering immune wave propagation, unidirectional transmission, and reflection-free energy transport. With this background, we provide a scheme to achieve robust high Q resonances in a metal-based topological photonic crystal (TPC) exhibiting defect-immune spectral characteristics in the microwave frequency regime. Coupled with a ring resonator, our proposed topological platform demonstrates the excitation of high Q resonances in the range 230-540. Except for the resonances, a robust microwave transmission (~0 dB) is observed in the investigated frequency regime 7.1-7.6 GHz, depicting a minimal scattering loss even around the sharp corners of the ring resonator. Further, the topological robustness of the propagating microwave and the excited resonances are examined by introducing an external Si obstacle at the domain interface. Our study reveals a minimal transmission loss (<7 dB) and negligible perturbation (<8%) in the Q factors when the Si barrier placed towards the input end of the straight topological waveguide. In addition, we have also demonstrated a novel way of exciting new resonances in the ring resonator that holds considerable promise for designing a TRR-based all-pass notch filter in the microwave regime.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"63 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140675551","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 : 2024-04-22DOI: 10.1088/1361-6463/ad415c
Rajkumar Patra, Apoorva Sharma, Hartmut Stöcker, M. Monecke, G. Salvan, Roland Mattheis, Heidemarie Schmidt
Polar unsaturated ferromagnetic thin films are promising for low-power and high-speed nonvolatile resistive and optical memories. Here we measure the magnetooptical (MO) response of polar unsaturated Co90Fe10 and Co40Fe40B20 thin films in the spectral range from 400 nm to 1000 nm using vector magnetooptical generalized ellipsometry (VMOGE) in an out-of-plane applied magnetic field of ±0.4 T where magnetization of the ferromagnetic (FM) thin film is not saturated. Using Magneto- Optical Simulation software (MagOpS®), we extract the complex MO coupling constant ( Q ) of the polar unsaturated FM thin films from difference spectra of VMOGE data recorded in polar configuration at Hz = +0.4 T and at Hz = −0.4 T. Presented approach opens a path to determine Q of both polar saturated and polar unsaturated FM thin films for simulating the MO properties of application-relevant optical memory multilayer structures.
极性不饱和铁磁薄膜有望用于低功耗和高速非易失性电阻和光学存储器。在这里，我们使用矢量磁光广义椭偏仪（VMOGE）测量极性不饱和 Co90Fe10 和 Co40Fe40B20 薄膜在 400 nm 到 1000 nm 光谱范围内的磁光（MO）响应，测量条件是在 ±0.4 T 的平面外外加磁场中铁磁（FM）薄膜的磁化未达到饱和。利用磁光模拟软件 (MagOpS®)，我们从 Hz = +0.4 T 和 Hz = -0.4 T 时以极性配置记录的 VMOGE 数据的差分光谱中提取了极性不饱和 FM 薄膜的复 MO 耦合常数 ( Q )。
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Pub Date : 2024-04-22DOI: 10.1088/1361-6463/ad415b
Duvan Mendoza Lopez, Gilbert Teyssedre, L. Boudou, L. Berquez, Christian Laurent, Shinya Iwata, Tatsuo Takada
The electronic properties of thin films of Poly(ethylene 2,6-naphthalate) –PEN, are investigated based on their photo-physical (optical absorption, photoluminescence) and electrical (space charge distribution, photo-stimulated discharge) behavior. Photo-stimulated currents are associated with optical absorption of the material leading to space charge dissipation as demonstrated by space charge distribution measurement. Based on this set of experimental results and quantum chemical calculation performed on PEN macromolecular system, we propose a new scheme for the electronic levels of PEN. This scheme allows understanding the mechanisms at play in photo-stimulated discharge. One of the main conclusions of our work is that photo-stimulated current measurements do not probe the energy level of traps. Detrapping of charges results from a two-step process where the photon energy is absorbed by chromophores that restitute a part of this energy to trapped charges through various mechanisms. Moreover, the new scheme allows discussing the components of the luminescence excited under different stresses, being electric field, electronic and UV irradiation, charge recombination and thermal activation.
{"title":"Electronic properties of polyethylene naphthalate as derived from photo-stimulated discharge, luminescence experiments and quantum chemical calculation","authors":"Duvan Mendoza Lopez, Gilbert Teyssedre, L. Boudou, L. Berquez, Christian Laurent, Shinya Iwata, Tatsuo Takada","doi":"10.1088/1361-6463/ad415b","DOIUrl":"https://doi.org/10.1088/1361-6463/ad415b","url":null,"abstract":"\u0000 The electronic properties of thin films of Poly(ethylene 2,6-naphthalate) –PEN, are investigated based on their photo-physical (optical absorption, photoluminescence) and electrical (space charge distribution, photo-stimulated discharge) behavior. Photo-stimulated currents are associated with optical absorption of the material leading to space charge dissipation as demonstrated by space charge distribution measurement. Based on this set of experimental results and quantum chemical calculation performed on PEN macromolecular system, we propose a new scheme for the electronic levels of PEN. This scheme allows understanding the mechanisms at play in photo-stimulated discharge. One of the main conclusions of our work is that photo-stimulated current measurements do not probe the energy level of traps. Detrapping of charges results from a two-step process where the photon energy is absorbed by chromophores that restitute a part of this energy to trapped charges through various mechanisms. Moreover, the new scheme allows discussing the components of the luminescence excited under different stresses, being electric field, electronic and UV irradiation, charge recombination and thermal activation.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"35 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140674365","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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