This article discusses the effect of polarization relaxation on dielectric breakdown. We establish analytical statistical Weibull distributions, taking into account the changing local electric field instead of the usual static field in acceleration models. The time dependence of the local field is expressed using the universal Curie–Von Schweidler law. The derived distribution fits well with various observations on time-to-breakdown statistical distributions. In the case of voltage square pulse alternative stress, the calculated time to breakdown follows a power law with stress frequency, regardless of the field dependence of the acceleration model, consistent with observations. The dielectric lifetime is longer compared to continuous voltage stress, as observed in transistors and integrated capacitors. The analytical expression of the power law exponent depends on the field acceleration model and polarization current. It matches well with the measured values for metal–oxide–semiconductor and metal insulator metal capacitors with different dielectrics. The power law exponent increases with the static dielectric constant. The Weibull shape factor is shown to be lower in the AC mode than in the DC mode, as observed. The AC signal duty factor effect decreases the lifetime in the AC mode. Finally, we demonstrate that the consequence of polarization relaxation also affects the lifetime in the DC mode. The acceleration factor and lifetime projections are close to power laws with the field, regardless of the static field dependence of the acceleration model.
{"title":"On the effect of polarization relaxation on dielectric breakdown","authors":"Serge Blonkowski","doi":"10.1063/5.0217634","DOIUrl":"https://doi.org/10.1063/5.0217634","url":null,"abstract":"This article discusses the effect of polarization relaxation on dielectric breakdown. We establish analytical statistical Weibull distributions, taking into account the changing local electric field instead of the usual static field in acceleration models. The time dependence of the local field is expressed using the universal Curie–Von Schweidler law. The derived distribution fits well with various observations on time-to-breakdown statistical distributions. In the case of voltage square pulse alternative stress, the calculated time to breakdown follows a power law with stress frequency, regardless of the field dependence of the acceleration model, consistent with observations. The dielectric lifetime is longer compared to continuous voltage stress, as observed in transistors and integrated capacitors. The analytical expression of the power law exponent depends on the field acceleration model and polarization current. It matches well with the measured values for metal–oxide–semiconductor and metal insulator metal capacitors with different dielectrics. The power law exponent increases with the static dielectric constant. The Weibull shape factor is shown to be lower in the AC mode than in the DC mode, as observed. The AC signal duty factor effect decreases the lifetime in the AC mode. Finally, we demonstrate that the consequence of polarization relaxation also affects the lifetime in the DC mode. The acceleration factor and lifetime projections are close to power laws with the field, regardless of the static field dependence of the acceleration model.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"86 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zixuan Ye, Raymond F. Smith, Marius Millot, Melissa Sims, Dimitrios Tsapetis, Michael D. Shields, Saransh Singh, Anirudh Hari, June K. Wicks
Laser-driven shock compression enables an experimental study of phase transitions at unprecedented pressures and temperatures. One example is the shock Hugoniot of magnesium oxide (MgO), which crosses the B1–B2-liquid triple point at 400–600 GPa, 10 000–13 000 K (0.86–1.12 eV). MgO is a major component within the mantles of terrestrial planets and has long been a focus of high-pressure research. Here, we combine time-resolved velocimetry and pyrometry measurements with a decaying shock platform to obtain pressure–temperature data on MgO from 300 to 1500 GPa and 9000 to 50 000 K. Pressure–temperature–density Hugoniot data are reported at 1500 GPa. These data represent the near-instantaneous response of an MgO [100] single crystal to shock compression. We report on a prominent temperature anomaly between 400 and 460 GPa, in general agreement with previous shock studies, and draw comparison with equation-of-state models. We provide a detailed analysis of the decaying shock compression platform, including a treatment of a pressure-dependent optical depth near the shock front. We show that if the optical depth of the shocked material is larger than 1 μm, treating the shock front as an optically thick gray body will lead to a noticeable overestimation of the shock temperature.
{"title":"Shock equation of state experiments in MgO up to 1.5 TPa and the effects of optical depth on temperature determination","authors":"Zixuan Ye, Raymond F. Smith, Marius Millot, Melissa Sims, Dimitrios Tsapetis, Michael D. Shields, Saransh Singh, Anirudh Hari, June K. Wicks","doi":"10.1063/5.0226765","DOIUrl":"https://doi.org/10.1063/5.0226765","url":null,"abstract":"Laser-driven shock compression enables an experimental study of phase transitions at unprecedented pressures and temperatures. One example is the shock Hugoniot of magnesium oxide (MgO), which crosses the B1–B2-liquid triple point at 400–600 GPa, 10 000–13 000 K (0.86–1.12 eV). MgO is a major component within the mantles of terrestrial planets and has long been a focus of high-pressure research. Here, we combine time-resolved velocimetry and pyrometry measurements with a decaying shock platform to obtain pressure–temperature data on MgO from 300 to 1500 GPa and 9000 to 50 000 K. Pressure–temperature–density Hugoniot data are reported at 1500 GPa. These data represent the near-instantaneous response of an MgO [100] single crystal to shock compression. We report on a prominent temperature anomaly between 400 and 460 GPa, in general agreement with previous shock studies, and draw comparison with equation-of-state models. We provide a detailed analysis of the decaying shock compression platform, including a treatment of a pressure-dependent optical depth near the shock front. We show that if the optical depth of the shocked material is larger than 1 μm, treating the shock front as an optically thick gray body will lead to a noticeable overestimation of the shock temperature.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"1 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Steffen Mittelmann, Jan Riedlinger, Benedikt Buchner, Thomas Schwarz-Selinger, Matej Mayer, Georg Pretzler
In approaches to analyze material composition or in processing tasks using ultra-short laser ablation, it is of particular interest how ablated materials are distributed across the solid angle in front of the interaction region. We found that with our sub-10-fs laser in the regime from 1014W/cm2 to 1017W/cm2, the solid angle of the ablation cone decreases significantly along with the laser intensity in a vacuum environment. For this observation, we used ion-beam analysis to investigate the distribution of tungsten collected on silicon catcher plates arranged across the solid angle of the laser-ablation cone. Moreover, we used other post-mortem tools, such as scanning electron microscopy and confocal laser scanning microscopy, to determine the ablation threshold of Fth=468mJ/cm2 of our tungsten samples. Here, clearly, two laser intensity-dependent ablation regimes can be observed in the detection of a crater depth and a ablation cone angle.
{"title":"Ablation characteristics of tungsten with ultra-short laser pulses","authors":"Steffen Mittelmann, Jan Riedlinger, Benedikt Buchner, Thomas Schwarz-Selinger, Matej Mayer, Georg Pretzler","doi":"10.1063/5.0222073","DOIUrl":"https://doi.org/10.1063/5.0222073","url":null,"abstract":"In approaches to analyze material composition or in processing tasks using ultra-short laser ablation, it is of particular interest how ablated materials are distributed across the solid angle in front of the interaction region. We found that with our sub-10-fs laser in the regime from 1014W/cm2 to 1017W/cm2, the solid angle of the ablation cone decreases significantly along with the laser intensity in a vacuum environment. For this observation, we used ion-beam analysis to investigate the distribution of tungsten collected on silicon catcher plates arranged across the solid angle of the laser-ablation cone. Moreover, we used other post-mortem tools, such as scanning electron microscopy and confocal laser scanning microscopy, to determine the ablation threshold of Fth=468mJ/cm2 of our tungsten samples. Here, clearly, two laser intensity-dependent ablation regimes can be observed in the detection of a crater depth and a ablation cone angle.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"29 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sanjay Mahat, Roshan Sharma, Hyunjo Jeong, Jingfei Liu
This study proposes a simple yet effective dynamic method that can nondestructively evaluate the elastic properties of homogeneous isotropic solid materials. Like some dynamic methods, such as resonance ultrasound spectrometry and impulse excitation technique, the proposed method consists of two steps: experimentally acquiring the specimen's natural frequencies and numerically calculating the elastic properties. Compared with the existing methods, the proposed method has much lower requirements on all four aspects of experimental operations: specimen preparation, specimen positioning, vibration excitation, and vibration detection. An inverse method based on finite element modal analysis is proposed to calculate the specimen's elastic properties, and it can deliver optimal estimations with high precision and accuracy. The performance of the proposed method was assessed using the well-established sound speed-based dynamic method, i.e., ultrasound pulse-echo testing. Taking a square aluminum specimen as an example, the differences in the measurements of Young's modulus and Poisson's ratio between these two methods are 2.25% and −2.07%, respectively; the differences in the measurements of shear modulus and bulk modulus are 0.01% and −1.46%, respectively. In summary, the proposed method provides a cheaper and experimentally simpler approach to determining the elastic properties of solid materials while maintaining accuracy and reliability similar to the established methods, which typically require sophisticated, costly equipment.
{"title":"Natural frequency informed finite element modal analysis method for estimating elastic properties of solid materials","authors":"Sanjay Mahat, Roshan Sharma, Hyunjo Jeong, Jingfei Liu","doi":"10.1063/5.0231087","DOIUrl":"https://doi.org/10.1063/5.0231087","url":null,"abstract":"This study proposes a simple yet effective dynamic method that can nondestructively evaluate the elastic properties of homogeneous isotropic solid materials. Like some dynamic methods, such as resonance ultrasound spectrometry and impulse excitation technique, the proposed method consists of two steps: experimentally acquiring the specimen's natural frequencies and numerically calculating the elastic properties. Compared with the existing methods, the proposed method has much lower requirements on all four aspects of experimental operations: specimen preparation, specimen positioning, vibration excitation, and vibration detection. An inverse method based on finite element modal analysis is proposed to calculate the specimen's elastic properties, and it can deliver optimal estimations with high precision and accuracy. The performance of the proposed method was assessed using the well-established sound speed-based dynamic method, i.e., ultrasound pulse-echo testing. Taking a square aluminum specimen as an example, the differences in the measurements of Young's modulus and Poisson's ratio between these two methods are 2.25% and −2.07%, respectively; the differences in the measurements of shear modulus and bulk modulus are 0.01% and −1.46%, respectively. In summary, the proposed method provides a cheaper and experimentally simpler approach to determining the elastic properties of solid materials while maintaining accuracy and reliability similar to the established methods, which typically require sophisticated, costly equipment.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"25 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. A. Shelkovenko, I. N. Tilikin, A. R. Mingaleev, V. M. Romanova, S. A. Pikuz
The paper presents the results of experimental studies of the operation of hybrid X-pinches on a modified high-current KING generator. The KING generator is a portable pulse current generator based on four low-inductive pulse capacitors. The output assembly of the generator was modified for greater diagnostic access to the load, which led to an increase in the inductance of the entire circuit and an increase in the duration of the current rise. A series of experiments with hybrid X-pinches with Al, Cu, and Mo wires with a diameter of 25 μm was carried out on the modified KING generator (200–260 kA, 220–280 ns, 45 kV). In experiments, it was shown that such a modification of the generator led to the stable formation of bright soft x-ray sources in X-pinches, suitable for use in point-projection radiography with a spatial resolution of about 10–15 μm.
本文介绍了在改进型大电流 KING 发生器上运行混合 X 针的实验研究结果。KING 发生器是一种基于四个低电感脉冲电容器的便携式脉冲电流发生器。对该发生器的输出组件进行了改装，以便对负载进行更多的诊断，从而增加了整个电路的电感量，并延长了电流上升的持续时间。在改装后的 KING 发生器（200-260 kA、220-280 ns、45 kV）上，使用直径为 25 μm 的铝线、铜线和钼线混合 X 针进行了一系列实验。实验表明，对发生器进行这样的改装，可以在 X 针中稳定地形成明亮的软 X 射线源，适用于空间分辨率约为 10-15 μm 的点投影射线照相术。
{"title":"Features of the formation of hot dense plasma in X-pinches on current generators based on low-inductive capacitors","authors":"T. A. Shelkovenko, I. N. Tilikin, A. R. Mingaleev, V. M. Romanova, S. A. Pikuz","doi":"10.1063/5.0220763","DOIUrl":"https://doi.org/10.1063/5.0220763","url":null,"abstract":"The paper presents the results of experimental studies of the operation of hybrid X-pinches on a modified high-current KING generator. The KING generator is a portable pulse current generator based on four low-inductive pulse capacitors. The output assembly of the generator was modified for greater diagnostic access to the load, which led to an increase in the inductance of the entire circuit and an increase in the duration of the current rise. A series of experiments with hybrid X-pinches with Al, Cu, and Mo wires with a diameter of 25 μm was carried out on the modified KING generator (200–260 kA, 220–280 ns, 45 kV). In experiments, it was shown that such a modification of the generator led to the stable formation of bright soft x-ray sources in X-pinches, suitable for use in point-projection radiography with a spatial resolution of about 10–15 μm.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"35 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amey Khanolkar, Amit Datye, Yan Zhang, Cody A. Dennett, Weiming Guo, Yang Liu, William J. Weber, Hua-Tay Lin, Yanwen Zhang
Multi-principal component transition metal (TM) diborides represent a class of high-entropy ceramics (HECs) that have received considerable interest in recent years owing to their promising properties for extreme environment applications that include thermal/ environmental barriers, hypersonic vehicles, turbine engines, and next-generation nuclear reactors. While the addition of chemical disorder through the random distribution of TM elements on the cation sublattice has offered opportunities to tailor elastic stiffness and hardness, the effects of irradiation-induced structural damage on the physical properties of these complex materials have remained largely unexplored. To this end, changes in the hardness and elastic moduli of a high-entropy TM diboride (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)B2 and three of its quaternary subsets following irradiation with 10 MeV gold (Au) ions to fluences of up to 6 × 1015 Au cm−2 are investigated at the micrometer and sub-micrometer length-scales via the dispersion of laser-generated surface acoustic waves (SAW) and nanoindentation, respectively. The nanoindentation measurements show that the TM diborides exhibit an initial increase in hardness following irradiation with energetic Au ions, with a subsequent decrease in hardness following further irradiation. One quaternary composition, (Hf1/3Ta1/3Ti1/3)B2, exhibits a notable exception to the trend and continues to exhibit an increase in hardness with ion irradiation fluence. Although differences in the absolute values of the effective elastic moduli obtained from the measured SAW dispersion and nanoindentation are observed (and attributed to microstructural variations at the measurement length-scale), both techniques yield similar trends in the form of an initial reduction and subsequent saturation in the elastic modulus with increasing ion irradiation fluence. The quaternary TM diboride (Hf1/3Ta1/3Ti1/3)B2 again exhibits a departure from this trend. The high-entropy TM diboride (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)B2 exhibits the greatest recovery in hardness and modulus when irradiated to high ion fluences following initial changes at low fluence, indicating superior resistance to radiation-induced damage over its quaternary counterparts. Opportunities for designing HECs with superior hardness and modulus for enhanced radiation resistance (compared to their single constituent counterparts) by tailoring chemical disorder and bond character in the lattice are discussed.
{"title":"Effects of irradiation damage on the hardness and elastic properties of quaternary and high entropy transition metal diborides","authors":"Amey Khanolkar, Amit Datye, Yan Zhang, Cody A. Dennett, Weiming Guo, Yang Liu, William J. Weber, Hua-Tay Lin, Yanwen Zhang","doi":"10.1063/5.0206224","DOIUrl":"https://doi.org/10.1063/5.0206224","url":null,"abstract":"Multi-principal component transition metal (TM) diborides represent a class of high-entropy ceramics (HECs) that have received considerable interest in recent years owing to their promising properties for extreme environment applications that include thermal/ environmental barriers, hypersonic vehicles, turbine engines, and next-generation nuclear reactors. While the addition of chemical disorder through the random distribution of TM elements on the cation sublattice has offered opportunities to tailor elastic stiffness and hardness, the effects of irradiation-induced structural damage on the physical properties of these complex materials have remained largely unexplored. To this end, changes in the hardness and elastic moduli of a high-entropy TM diboride (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)B2 and three of its quaternary subsets following irradiation with 10 MeV gold (Au) ions to fluences of up to 6 × 1015 Au cm−2 are investigated at the micrometer and sub-micrometer length-scales via the dispersion of laser-generated surface acoustic waves (SAW) and nanoindentation, respectively. The nanoindentation measurements show that the TM diborides exhibit an initial increase in hardness following irradiation with energetic Au ions, with a subsequent decrease in hardness following further irradiation. One quaternary composition, (Hf1/3Ta1/3Ti1/3)B2, exhibits a notable exception to the trend and continues to exhibit an increase in hardness with ion irradiation fluence. Although differences in the absolute values of the effective elastic moduli obtained from the measured SAW dispersion and nanoindentation are observed (and attributed to microstructural variations at the measurement length-scale), both techniques yield similar trends in the form of an initial reduction and subsequent saturation in the elastic modulus with increasing ion irradiation fluence. The quaternary TM diboride (Hf1/3Ta1/3Ti1/3)B2 again exhibits a departure from this trend. The high-entropy TM diboride (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)B2 exhibits the greatest recovery in hardness and modulus when irradiated to high ion fluences following initial changes at low fluence, indicating superior resistance to radiation-induced damage over its quaternary counterparts. Opportunities for designing HECs with superior hardness and modulus for enhanced radiation resistance (compared to their single constituent counterparts) by tailoring chemical disorder and bond character in the lattice are discussed.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"8 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bao Zhu, Ze Shang, Chenyan Wang, Xiaohan Wu, David Wei Zhang
Al2O3/ZrO2 (A/Z) layers with embedded Pt nanoparticles (Pt-nps) at the interface of A/Z have been used to create a dielectric film with an enhanced permittivity. The Pt-nps and dielectrics are both grown by the atomic layer deposition process, which is complementary metal–oxide–semiconductor compatible. In order to control the thickness ratio of Pt-nps in the overall dielectrics more easily, the thickness of the ZrO2 layer is changed from 12 to 30 nm with a fixed thickness of 12 nm for Al2O3 and constant growth cycles of 70 for Pt-nps. The results show that the introduction of Pt-nps is beneficial to the enhancement of the dielectric permittivity. As the thickness of ZrO2 is 30 nm, the capacitance density increases from 2.5 to 5.1 fF/μm2 with the addition of Pt-nps, i.e., a doubling of the capacitance density achieved. Additionally, the leakage current at 2 V increases from 1.1 × 10−8 to 1.5 × 10−7 A/cm2. Furthermore, the dielectric breakdown field decreases from 5.4 to 2.7 MV/cm. The electric field distribution simulation and charging–discharging test imply that interfacial polarization is built at the interface of Pt-nps and the dielectric films, which contributes to the dielectric permittivity enhancement, and local electric field increasing in the affinity of Pt-nps gives rise to the deterioration of the leakage current and breakdown electric field.
{"title":"Permittivity enhancement of Al2O3/ZrO2 dielectrics with the incorporation of Pt nanoparticles","authors":"Bao Zhu, Ze Shang, Chenyan Wang, Xiaohan Wu, David Wei Zhang","doi":"10.1063/5.0218456","DOIUrl":"https://doi.org/10.1063/5.0218456","url":null,"abstract":"Al2O3/ZrO2 (A/Z) layers with embedded Pt nanoparticles (Pt-nps) at the interface of A/Z have been used to create a dielectric film with an enhanced permittivity. The Pt-nps and dielectrics are both grown by the atomic layer deposition process, which is complementary metal–oxide–semiconductor compatible. In order to control the thickness ratio of Pt-nps in the overall dielectrics more easily, the thickness of the ZrO2 layer is changed from 12 to 30 nm with a fixed thickness of 12 nm for Al2O3 and constant growth cycles of 70 for Pt-nps. The results show that the introduction of Pt-nps is beneficial to the enhancement of the dielectric permittivity. As the thickness of ZrO2 is 30 nm, the capacitance density increases from 2.5 to 5.1 fF/μm2 with the addition of Pt-nps, i.e., a doubling of the capacitance density achieved. Additionally, the leakage current at 2 V increases from 1.1 × 10−8 to 1.5 × 10−7 A/cm2. Furthermore, the dielectric breakdown field decreases from 5.4 to 2.7 MV/cm. The electric field distribution simulation and charging–discharging test imply that interfacial polarization is built at the interface of Pt-nps and the dielectric films, which contributes to the dielectric permittivity enhancement, and local electric field increasing in the affinity of Pt-nps gives rise to the deterioration of the leakage current and breakdown electric field.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"9 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaozhuo Xu, Kai Hua, Haichao Feng, Siyuan Jiang, Yunji Zhao
In this paper, a novel method for suppressing the detent force of permanent magnet linear synchronous motors is proposed. First, the end force is adjusted to offset the cogging force while the cogging force remains unchanged. On the other hand, the proposed method can arbitrarily change the shape of the end magnetic regulating module (EMRM), thus allowing the end force to obtain a wider adjustment range, which is different from the conventional limited shape optimization. More interestingly, compared to the traditional approach for suppressing the end force, which is to suppress the end force to the lowest level, the proposed method does not necessarily suppress the end force to the lowest level, but rather adjusts it to a reasonable level, so that it can offset the cogging force. This leads to the fact that the optimized end magnetic regulating module is effective in adjusting the end force and may even increase the end force, which is different from the conventional idea of suppressing the detent force. Next, the optimal EMRM's topologies are solved using the optimization algorithm, which replaces the traditional low-dimensional single-direction optimization and performs multi-direction global search. Finally, the prototype with optimal EMRM's topology and the testing platform are established and the experimental results validate the effectiveness of the proposed method.
{"title":"Minimization of detent force in PMLSM by end magnetic regulating module with free topologies","authors":"Xiaozhuo Xu, Kai Hua, Haichao Feng, Siyuan Jiang, Yunji Zhao","doi":"10.1063/5.0232229","DOIUrl":"https://doi.org/10.1063/5.0232229","url":null,"abstract":"In this paper, a novel method for suppressing the detent force of permanent magnet linear synchronous motors is proposed. First, the end force is adjusted to offset the cogging force while the cogging force remains unchanged. On the other hand, the proposed method can arbitrarily change the shape of the end magnetic regulating module (EMRM), thus allowing the end force to obtain a wider adjustment range, which is different from the conventional limited shape optimization. More interestingly, compared to the traditional approach for suppressing the end force, which is to suppress the end force to the lowest level, the proposed method does not necessarily suppress the end force to the lowest level, but rather adjusts it to a reasonable level, so that it can offset the cogging force. This leads to the fact that the optimized end magnetic regulating module is effective in adjusting the end force and may even increase the end force, which is different from the conventional idea of suppressing the detent force. Next, the optimal EMRM's topologies are solved using the optimization algorithm, which replaces the traditional low-dimensional single-direction optimization and performs multi-direction global search. Finally, the prototype with optimal EMRM's topology and the testing platform are established and the experimental results validate the effectiveness of the proposed method.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"21 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jing-Ci Su, Shih-Hung Cheng, Sin-You Huang, Wen-Jeng Hsueh
The urgent demand for high-performance emerging memory, propelled by artificial intelligence in internet of things (AIoT) and machine learning advancements, spotlights spin-transfer torque magnetic random-access memory as a prime candidate for practical application. However, magnetic tunnel junctions (MTJs) with a single-crystalline MgO barrier, which are central to magnetic random-access memory (MRAM), suffer from significant drawbacks: insufficient endurance due to breakdown and high writing power requirements. A superlattice barrier-based MTJ (SL-MTJ) is proposed to overcome the limitation. We first fabricated the MTJ using an SL barrier while examining the magnetoresistance and resistance-area product. Lower writing power can be achieved in SL-MTJs compared to MgO-MTJs. Our study may provide a new route to the development of MRAM technologies.
{"title":"Magnetic tunnel junctions with superlattice barriers","authors":"Jing-Ci Su, Shih-Hung Cheng, Sin-You Huang, Wen-Jeng Hsueh","doi":"10.1063/5.0228748","DOIUrl":"https://doi.org/10.1063/5.0228748","url":null,"abstract":"The urgent demand for high-performance emerging memory, propelled by artificial intelligence in internet of things (AIoT) and machine learning advancements, spotlights spin-transfer torque magnetic random-access memory as a prime candidate for practical application. However, magnetic tunnel junctions (MTJs) with a single-crystalline MgO barrier, which are central to magnetic random-access memory (MRAM), suffer from significant drawbacks: insufficient endurance due to breakdown and high writing power requirements. A superlattice barrier-based MTJ (SL-MTJ) is proposed to overcome the limitation. We first fabricated the MTJ using an SL barrier while examining the magnetoresistance and resistance-area product. Lower writing power can be achieved in SL-MTJs compared to MgO-MTJs. Our study may provide a new route to the development of MRAM technologies.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"63 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Exploring potential two-dimensional monolayers with large photogalvanic effect (PGE) has been of great importance for developing self-powered optoelectronic devices. In this paper, we systematically investigate the generation of PGE photocurrent in chalcogen-based Janus XYZ monolayers (X/Y/Z = S, Se, Te; X ≠ Y ≠ Z) based on non-equilibrium Green's function formalism with density functional theory. The optimized Janus SSeTe, SeSTe, and TeSeS monolayers in the rectangular phase are shown stable and, respectively, possess 1.54, 1.49, and 1.74 eV indirect bandgaps. Illuminated by linearly polarized light, the PGE photocurrent without bias voltage can be collected in both armchair and zigzag directions. Unlike common Janus 2D materials with C3v symmetry, the photocurrent peak values of Janus XYZ monolayers do not come up with certain polarization angles, while the relations can be fitted by Iph = α sin(2θ) + β cos(2θ) + γ at each photon energy. Meanwhile, the maximum photoresponses of Janus SSeTe, SeSTe, and TeSeS monolayers are 2.02, 3.33, and 4.42 a20/photon, respectively. The relatively large PGE photocurrents and complicated polarization relations result from the lower symmetry of Janus XYZ monolayers. Moreover, the specific polarization angles for maximum photoresponses at each photon energy and the ratio between two transport directions are demonstrated, reflecting the anisotropy. Our results theoretically predict a potential Janus monolayer family for self-powered optoelectronic applications.
{"title":"Theoretical prediction of chalcogen-based Janus monolayers for self-powered optoelectronic devices","authors":"Yuxuan Sun, Naizhang Sun, Wenlin Zhou, Han Ye","doi":"10.1063/5.0223915","DOIUrl":"https://doi.org/10.1063/5.0223915","url":null,"abstract":"Exploring potential two-dimensional monolayers with large photogalvanic effect (PGE) has been of great importance for developing self-powered optoelectronic devices. In this paper, we systematically investigate the generation of PGE photocurrent in chalcogen-based Janus XYZ monolayers (X/Y/Z = S, Se, Te; X ≠ Y ≠ Z) based on non-equilibrium Green's function formalism with density functional theory. The optimized Janus SSeTe, SeSTe, and TeSeS monolayers in the rectangular phase are shown stable and, respectively, possess 1.54, 1.49, and 1.74 eV indirect bandgaps. Illuminated by linearly polarized light, the PGE photocurrent without bias voltage can be collected in both armchair and zigzag directions. Unlike common Janus 2D materials with C3v symmetry, the photocurrent peak values of Janus XYZ monolayers do not come up with certain polarization angles, while the relations can be fitted by Iph = α sin(2θ) + β cos(2θ) + γ at each photon energy. Meanwhile, the maximum photoresponses of Janus SSeTe, SeSTe, and TeSeS monolayers are 2.02, 3.33, and 4.42 a20/photon, respectively. The relatively large PGE photocurrents and complicated polarization relations result from the lower symmetry of Janus XYZ monolayers. Moreover, the specific polarization angles for maximum photoresponses at each photon energy and the ratio between two transport directions are demonstrated, reflecting the anisotropy. Our results theoretically predict a potential Janus monolayer family for self-powered optoelectronic applications.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"43 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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