Pub Date : 2024-08-28Epub Date: 2024-08-26DOI: 10.1063/5.0226603
Hao Liang, Xinqiang Yan
The calculation of the demagnetization field is crucial in various disciplines, including magnetic resonance imaging and micromagnetics. A standard method involves discretizing the spatial domain into finite difference cells and using demagnetization tensors to compute the field. Different demagnetization tensors can result in contributions from adjacent cells that do not approach zero, nor do their differences, even as the cell size decreases. This work demonstrates that in three-dimensional space, a specific set of magnetization tensors produces the same total demagnetization field as the Cauchy principal value when the cell size approaches zero. Additionally, we provide a lower bound for the convergence speed, validated through numerical experiments.
{"title":"On the equivalence of demagnetization tensors as discrete cell size approaches zero in three-dimensional space.","authors":"Hao Liang, Xinqiang Yan","doi":"10.1063/5.0226603","DOIUrl":"10.1063/5.0226603","url":null,"abstract":"<p><p>The calculation of the demagnetization field is crucial in various disciplines, including magnetic resonance imaging and micromagnetics. A standard method involves discretizing the spatial domain into finite difference cells and using demagnetization tensors to compute the field. Different demagnetization tensors can result in contributions from adjacent cells that do not approach zero, nor do their differences, even as the cell size decreases. This work demonstrates that in three-dimensional space, a specific set of magnetization tensors produces the same total demagnetization field as the Cauchy principal value when the cell size approaches zero. Additionally, we provide a lower bound for the convergence speed, validated through numerical experiments.</p>","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11365609/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142107747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The strengths of glasses are intricately linked to their atomic-level heterogeneity. Atomistic simulations are frequently used to investigate the statistical physics of this relationship, compensating for the limited spatiotemporal resolution in experimental studies. However, theoretical insights are limited by the complexity of glass structures and the accuracy of the interatomic potentials used in simulations. Here, we investigate the strengths and fracture mechanisms of 2D silica, with all structural units accessible to direct experimental observation. We develop a neural network force field for fracture based on the deep potential-smooth edition framework. Representative atomic structures across crystals, nanocrystalline, paracrystalline, and continuous random network glasses are studied. We find that the virials or bond lengths control the initialization of bond-breaking events, creating nanoscale voids in the vitreous network. However, the voids do not necessarily lead to crack propagation due to a disorder-trapping effect, which is stronger than the lattice-trapping effect in a crystalline lattice, and occurs over larger length and time scales. Fracture initiation proceeds with void growth and coalescence and advances through a bridging mechanism. The fracture patterns are shaped by subsequent trapping and cleavage steps, often guided by voids forming ahead of the crack tip. These heterogeneous processes result in atomically smooth facets in crystalline regions and rough, amorphous edges in the glassy phase. These insights into 2D crystals and glasses, both sharing SiO2 chemistry, highlight the pivotal role of atomic-level structures in determining fracture kinetics and crack path selection in materials.
{"title":"Strength of 2D glasses explored by machine-learning force fields","authors":"Pengjie Shi, Zhiping Xu","doi":"10.1063/5.0215663","DOIUrl":"https://doi.org/10.1063/5.0215663","url":null,"abstract":"The strengths of glasses are intricately linked to their atomic-level heterogeneity. Atomistic simulations are frequently used to investigate the statistical physics of this relationship, compensating for the limited spatiotemporal resolution in experimental studies. However, theoretical insights are limited by the complexity of glass structures and the accuracy of the interatomic potentials used in simulations. Here, we investigate the strengths and fracture mechanisms of 2D silica, with all structural units accessible to direct experimental observation. We develop a neural network force field for fracture based on the deep potential-smooth edition framework. Representative atomic structures across crystals, nanocrystalline, paracrystalline, and continuous random network glasses are studied. We find that the virials or bond lengths control the initialization of bond-breaking events, creating nanoscale voids in the vitreous network. However, the voids do not necessarily lead to crack propagation due to a disorder-trapping effect, which is stronger than the lattice-trapping effect in a crystalline lattice, and occurs over larger length and time scales. Fracture initiation proceeds with void growth and coalescence and advances through a bridging mechanism. The fracture patterns are shaped by subsequent trapping and cleavage steps, often guided by voids forming ahead of the crack tip. These heterogeneous processes result in atomically smooth facets in crystalline regions and rough, amorphous edges in the glassy phase. These insights into 2D crystals and glasses, both sharing SiO2 chemistry, highlight the pivotal role of atomic-level structures in determining fracture kinetics and crack path selection in materials.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940752","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}
Ia. A. Filatov, P. I. Gerevenkov, N. E. Khokhlov, A. M. Kalashnikova
We present a concept for selective excitation of magnetostatic surface waves with a quasi-discrete spectrum using spatially patterned femtosecond laser pulses inducing either an ultrafast change of magnetic anisotropy or an inverse Faraday effect. We micromagnetically simulate the excitation of the waves with a periodically patterned uni- or bipolar laser impact. Such excitation yields multiple wavepackets propagating with different group velocities, whose dispersion corresponds to the set of quasi-discrete points. In addition, we show that the frequency of the spectral peaks can be controlled by the polarity of the periodic impact and its spatial period. The presented consideration of multiple spatially periodic magnetostatic surface wave sources as a whole enables implementation of a comprehensive toolkit of spatiotemporal optical methods for tunable excitation and control of spin-wave parameters.
{"title":"Tunable quasi-discrete spectrum of spin waves excited by periodic laser patterns","authors":"Ia. A. Filatov, P. I. Gerevenkov, N. E. Khokhlov, A. M. Kalashnikova","doi":"10.1063/5.0216091","DOIUrl":"https://doi.org/10.1063/5.0216091","url":null,"abstract":"We present a concept for selective excitation of magnetostatic surface waves with a quasi-discrete spectrum using spatially patterned femtosecond laser pulses inducing either an ultrafast change of magnetic anisotropy or an inverse Faraday effect. We micromagnetically simulate the excitation of the waves with a periodically patterned uni- or bipolar laser impact. Such excitation yields multiple wavepackets propagating with different group velocities, whose dispersion corresponds to the set of quasi-discrete points. In addition, we show that the frequency of the spectral peaks can be controlled by the polarity of the periodic impact and its spatial period. The presented consideration of multiple spatially periodic magnetostatic surface wave sources as a whole enables implementation of a comprehensive toolkit of spatiotemporal optical methods for tunable excitation and control of spin-wave parameters.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940751","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}
The successful synthesis and discovery of unique properties in two-dimensional Janus materials have positioned them as promising candidates for applications in sensors, field-effect transistors, and ultrasensitive detectors. In this study, we utilized first-principles calculations to predict a novel Janus CeIBr monolayer. Our calculations show that Janus CeIBr monolayer behaves as a bipolar magnetic semiconductor, demonstrating both mechanical and thermodynamic stability, along with a high Curie temperature of 242 K and in-plane magnetic anisotropy (102.92 meV). A notable intrinsic valley splitting of 66 meV is also evident in CeIBr, highlighting its distinctive valley contrast characteristic. Furthermore, the application of biaxial strain effectively transforms the magnetic ground state of CeIBr from a ferromagnetic state to an antiferromagnetic state and alters the direction of the easy magnetization axis from in-plane to out-of-plane. Our findings offer a theoretical foundation for the design of novel anomalous valley Hall effect-based electronic devices utilizing the Janus CeIBr monolayer.
{"title":"A new two-dimensional intrinsic ferrovalley material: Janus CeIBr monolayer","authors":"Shujing Li, JiaPeng Lv","doi":"10.1063/5.0206486","DOIUrl":"https://doi.org/10.1063/5.0206486","url":null,"abstract":"The successful synthesis and discovery of unique properties in two-dimensional Janus materials have positioned them as promising candidates for applications in sensors, field-effect transistors, and ultrasensitive detectors. In this study, we utilized first-principles calculations to predict a novel Janus CeIBr monolayer. Our calculations show that Janus CeIBr monolayer behaves as a bipolar magnetic semiconductor, demonstrating both mechanical and thermodynamic stability, along with a high Curie temperature of 242 K and in-plane magnetic anisotropy (102.92 meV). A notable intrinsic valley splitting of 66 meV is also evident in CeIBr, highlighting its distinctive valley contrast characteristic. Furthermore, the application of biaxial strain effectively transforms the magnetic ground state of CeIBr from a ferromagnetic state to an antiferromagnetic state and alters the direction of the easy magnetization axis from in-plane to out-of-plane. Our findings offer a theoretical foundation for the design of novel anomalous valley Hall effect-based electronic devices utilizing the Janus CeIBr monolayer.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940800","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}
Aman Gupta, Gyan Shankar, Saurabh Pawar, Shi-Hoon Choi, Satyam Suwas
In this study, a TiNbCrTa refractory complex concentrated alloy (RCCA) was prepared using vacuum arc remelting. The microstructural evolution and mechanical properties of both as-cast and heat-treated RCCA samples were analyzed. Heat treatment (HT) was performed at 800–1200 °C for 1 h in a vacuum-sealed environment. These samples exhibited a formation of Cr2Nb and Cr2Ti Laves phases. A variation in elemental distribution was observed, with interdendritic (ID) regions showing higher fractions of Ti and Cr, while the dendritic regions had a greater concentration of Ta and Nb. Micro-segregation at the IDs was confirmed through energy dispersive x-ray spectroscopy mapping, which inferred the formation of Cr- and Ti-rich phases during HT at 800–1200 °C. High-temperature HT at 1200 °C for 1 h led to the evolution of the hcp omega phase. Prolonged HT at 1200 °C for 96 h resulted in the evolution of a Cr-rich Laves phase (Cr2Ta), which was homogeneously distributed within the microstructure, indicating an unstable microstructure. Furthermore, despite prolonged HT, a variation in the elemental distribution persisted due to the presence of dendritic and ID regions. Electron backscattered diffraction analysis revealed the presence of bcc and hcp phases in the dendritic and ID regions, respectively, of the as-cast and HTed samples. The as-cast samples demonstrated a high compressive strength of approximately 2 GPa. Micro-hardness values increased with the HT temperature up to 1000 °C. Further increases under HT conditions did not significantly reduce the microhardness value, whereas prolonged HT at 1200 °C led to an increase in the microhardness value. Overall, the newly developed TiNbCrTa RCCA exhibited high-strength behavior even after the phase transformation.
本研究采用真空电弧重熔法制备了一种 TiNbCrTa 难熔复合浓缩合金（RCCA）。分析了铸造和热处理 RCCA 样品的微观结构演变和机械性能。热处理（HT）是在真空密封环境中于 800-1200 °C 下进行的，持续时间为 1 小时。这些样品形成了 Cr2Nb 和 Cr2Ti Laves 相。观察到元素分布的变化，树枝间（ID）区域的钛和铬含量较高，而树枝状区域的钽和铌含量较高。能量色散 X 射线光谱图证实了 ID 区的微偏析，推断出在 800-1200 °C 高温热处理过程中形成了富含铬和钛的相。在 1200 °C高温加热 1 小时后，形成了 hcp ω 相。在 1200 °C下持续高温 96 小时后，演化出富含铬的 Laves 相（Cr2Ta），该相在微观结构中分布均匀，表明微观结构不稳定。此外，尽管高温煅烧时间较长，但由于存在树枝状和 ID 区，元素分布仍然存在变化。电子反向散射衍射分析表明，在原铸样品和高温处理样品的树枝状区域和 ID 区域分别存在 bcc 相和 hcp 相。原样铸造的样品具有约 2 GPa 的高抗压强度。显微硬度值随着高温炉温度的升高而增加，最高可达 1000 °C。在高温条件下进一步提高温度并不会明显降低显微硬度值，而在 1200 °C 下长时间高温则会导致显微硬度值增加。总体而言，新开发的 TiNbCrTa RCCA 在相变后仍表现出高强度特性。
{"title":"Microstructural stability and mechanical properties of the as-cast and heat-treated newly developed TiNbCrTa refractory complex concentrated alloy","authors":"Aman Gupta, Gyan Shankar, Saurabh Pawar, Shi-Hoon Choi, Satyam Suwas","doi":"10.1063/5.0206425","DOIUrl":"https://doi.org/10.1063/5.0206425","url":null,"abstract":"In this study, a TiNbCrTa refractory complex concentrated alloy (RCCA) was prepared using vacuum arc remelting. The microstructural evolution and mechanical properties of both as-cast and heat-treated RCCA samples were analyzed. Heat treatment (HT) was performed at 800–1200 °C for 1 h in a vacuum-sealed environment. These samples exhibited a formation of Cr2Nb and Cr2Ti Laves phases. A variation in elemental distribution was observed, with interdendritic (ID) regions showing higher fractions of Ti and Cr, while the dendritic regions had a greater concentration of Ta and Nb. Micro-segregation at the IDs was confirmed through energy dispersive x-ray spectroscopy mapping, which inferred the formation of Cr- and Ti-rich phases during HT at 800–1200 °C. High-temperature HT at 1200 °C for 1 h led to the evolution of the hcp omega phase. Prolonged HT at 1200 °C for 96 h resulted in the evolution of a Cr-rich Laves phase (Cr2Ta), which was homogeneously distributed within the microstructure, indicating an unstable microstructure. Furthermore, despite prolonged HT, a variation in the elemental distribution persisted due to the presence of dendritic and ID regions. Electron backscattered diffraction analysis revealed the presence of bcc and hcp phases in the dendritic and ID regions, respectively, of the as-cast and HTed samples. The as-cast samples demonstrated a high compressive strength of approximately 2 GPa. Micro-hardness values increased with the HT temperature up to 1000 °C. Further increases under HT conditions did not significantly reduce the microhardness value, whereas prolonged HT at 1200 °C led to an increase in the microhardness value. Overall, the newly developed TiNbCrTa RCCA exhibited high-strength behavior even after the phase transformation.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940802","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}
Anup Yadav, Tim Niewelt, Sophie L. Pain, Nicholas E. Grant, James S. Lord, Koji Yokoyama, John D. Murphy
Muons are part of natural cosmic radiation but can also be generated at spallation sources for material science and particle physics applications. Recently, pulsed muons have been used to characterize the density of free charge carriers in semiconductors and their recombination lifetime. Muon beam irradiation can also result in the formation of dilute levels of crystal defects in silicon. These crystal defects are only detected in high carrier lifetime silicon samples that are highly sensitive to defects due to their long recombination lifetimes. This work investigates the characteristics of these defects in terms of their formation, recombination activity, and deactivation. Charge carrier lifetime assessments and photoluminescence imaging have great sensitivity to measure the generated defects in high-quality silicon samples exposed to ∼4 MeV (anti)muons and their recombination activity despite the extremely low concentration. The defects reduce the effective charge carrier lifetime of both p- and n-type silicon and appear to be more detrimental to n-type silicon. Defects are created by transmission of muons through the wafer, and there are indications that slowed or implanted muons may create additional defects. In a post-exposure isochronal annealing study, we observe that annealing at temperatures of up to 450 °C does not by itself fully deactivate the defects. A recovery of charge carrier lifetime was observed when the annealing was combined with Al2O3 surface passivation, probably due to passivation of bulk defects from hydrogen from the dielectric film.
μ介子是自然宇宙辐射的一部分，但也可以在材料科学和粒子物理应用的溅射源中产生。最近，脉冲μ介子被用于描述半导体中自由电荷载流子的密度及其重组寿命。μ介子束辐照还能在硅中形成稀释水平的晶体缺陷。只有在高载流子寿命的硅样品中才能检测到这些晶体缺陷，而硅样品由于其较长的重组寿命而对缺陷高度敏感。这项工作研究了这些缺陷在形成、重组活动和失活方面的特征。电荷载流子寿命评估和光致发光成像具有极高的灵敏度，可以测量暴露于 ∼4 MeV （反）μ介子的高质量硅样品中产生的缺陷及其重组活动，尽管其浓度极低。缺陷降低了p型和n型硅的有效电荷载流子寿命，似乎对n型硅更为有害。缺陷是由μ介子穿过硅片产生的，有迹象表明，减缓或植入的μ介子可能会产生更多的缺陷。在暴露后的等速退火研究中，我们观察到在高达 450 °C 的温度下进行退火本身并不能使缺陷完全失活。当退火与 Al2O3 表面钝化相结合时，电荷载流子寿命得以恢复，这可能是由于介质薄膜中的氢钝化了块状缺陷。
{"title":"Formation and annihilation of bulk recombination-active defects induced by muon irradiation of crystalline silicon","authors":"Anup Yadav, Tim Niewelt, Sophie L. Pain, Nicholas E. Grant, James S. Lord, Koji Yokoyama, John D. Murphy","doi":"10.1063/5.0217952","DOIUrl":"https://doi.org/10.1063/5.0217952","url":null,"abstract":"Muons are part of natural cosmic radiation but can also be generated at spallation sources for material science and particle physics applications. Recently, pulsed muons have been used to characterize the density of free charge carriers in semiconductors and their recombination lifetime. Muon beam irradiation can also result in the formation of dilute levels of crystal defects in silicon. These crystal defects are only detected in high carrier lifetime silicon samples that are highly sensitive to defects due to their long recombination lifetimes. This work investigates the characteristics of these defects in terms of their formation, recombination activity, and deactivation. Charge carrier lifetime assessments and photoluminescence imaging have great sensitivity to measure the generated defects in high-quality silicon samples exposed to ∼4 MeV (anti)muons and their recombination activity despite the extremely low concentration. The defects reduce the effective charge carrier lifetime of both p- and n-type silicon and appear to be more detrimental to n-type silicon. Defects are created by transmission of muons through the wafer, and there are indications that slowed or implanted muons may create additional defects. In a post-exposure isochronal annealing study, we observe that annealing at temperatures of up to 450 °C does not by itself fully deactivate the defects. A recovery of charge carrier lifetime was observed when the annealing was combined with Al2O3 surface passivation, probably due to passivation of bulk defects from hydrogen from the dielectric film.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940801","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}
Controlling the placement of dopants can significantly tailor graphene's properties, but this process is influenced by copper substrates during vapor deposition. Understanding the influence of interfacial atomic structures on the preference for dopant locations is crucial. In this work, we conducted a systematic first-principles study of boron- and nitrogen-doped graphene on copper {111}, considering both sublattice and superlattice configurations. Our calculations revealed that the formation energy is minimized at the top-fccb site (−0.60 eV) for boron and the hcp-fcca site (1.94 eV) for nitrogen, suggesting a possible selective distribution of dopants in both sublattice and superlattice arrangements at the graphene/copper interface. Furthermore, a lower formation energy indicates a higher release of energy during doping, resulting in a stronger interfacial binding. Since formation energy is closely associated with out-of-plane interactions, while in-plane interactions remain relatively stable, these differences offer potential avenues for modifying dopant distribution at graphene/copper interfaces.
{"title":"Location preference of boron and nitrogen dopants at graphene/copper interface","authors":"Boan Zhong, Jiamiao Ni, Qi Zhang, Jian Song, Yue Liu, Mingyu Gong, Tongxiang Fan","doi":"10.1063/5.0197184","DOIUrl":"https://doi.org/10.1063/5.0197184","url":null,"abstract":"Controlling the placement of dopants can significantly tailor graphene's properties, but this process is influenced by copper substrates during vapor deposition. Understanding the influence of interfacial atomic structures on the preference for dopant locations is crucial. In this work, we conducted a systematic first-principles study of boron- and nitrogen-doped graphene on copper {111}, considering both sublattice and superlattice configurations. Our calculations revealed that the formation energy is minimized at the top-fccb site (−0.60 eV) for boron and the hcp-fcca site (1.94 eV) for nitrogen, suggesting a possible selective distribution of dopants in both sublattice and superlattice arrangements at the graphene/copper interface. Furthermore, a lower formation energy indicates a higher release of energy during doping, resulting in a stronger interfacial binding. Since formation energy is closely associated with out-of-plane interactions, while in-plane interactions remain relatively stable, these differences offer potential avenues for modifying dopant distribution at graphene/copper interfaces.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141969172","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}
Hong Yang, Michael R. Armstrong, Ryan A. Austin, Harry B. Radousky, Akshat Hetal Patel, Tiwei Wei, Alexander F. Goncharov, Wendy L. Mao, Eduardo Granados, Hae Ja Lee, Inhyuk Nam, Bob Nagler, Peter Walter, Jonathan L. Belof, Shaughnessy B. Brown, Vitali Prakapenka, Sergey S. Lobanov, Clemens Prescher, Nicolas Holtgrewe, Elissaios Stavrou, Paulius V. Grivickas, Arianna E. Gleason
Shock experiments are widely used to understand the mechanical and electronic properties of matter under extreme conditions. However, after shock loading to a Hugoniot state, a clear description of the post-shock thermal state and its impacts on materials is still lacking. We used diffraction patterns from 100-fs x-ray pulses to investigate the temperature evolution of laser-shocked Al–Zr metal film composites at time delays ranging from 5 to 75 ns driven by a 120-ps short-pulse laser. We found significant heating of both Al and Zr after shock release, which can be attributed to heat generated by inelastic deformation. A conventional hydrodynamic model that employs (i) typical descriptions of Al and Zr mechanical strength and (ii) elevated strength responses (which might be attributed to an unknown strain rate dependence) did not fully account for the measured temperature increase, which suggests that other strength-related mechanisms (such as fine-scale void growth) could play an important role in thermal responses under shock wave loading/unloading cycles. Our results suggest that a significant portion of the total shock energy delivered by lasers becomes heat due to defect-facilitated plastic work, leaving less converted to kinetic energy. This heating effect may be common in laser-shocked experiments but has not been well acknowledged. High post-shock temperatures may induce phase transformation of materials during shock release. Another implication for the study is the preservability of magnetic records from planetary surfaces that have a shock history from frequent impact events.
{"title":"Evidence of non-isentropic release from high residual temperatures in shocked metals measured with ultrafast x-ray diffraction","authors":"Hong Yang, Michael R. Armstrong, Ryan A. Austin, Harry B. Radousky, Akshat Hetal Patel, Tiwei Wei, Alexander F. Goncharov, Wendy L. Mao, Eduardo Granados, Hae Ja Lee, Inhyuk Nam, Bob Nagler, Peter Walter, Jonathan L. Belof, Shaughnessy B. Brown, Vitali Prakapenka, Sergey S. Lobanov, Clemens Prescher, Nicolas Holtgrewe, Elissaios Stavrou, Paulius V. Grivickas, Arianna E. Gleason","doi":"10.1063/5.0217779","DOIUrl":"https://doi.org/10.1063/5.0217779","url":null,"abstract":"Shock experiments are widely used to understand the mechanical and electronic properties of matter under extreme conditions. However, after shock loading to a Hugoniot state, a clear description of the post-shock thermal state and its impacts on materials is still lacking. We used diffraction patterns from 100-fs x-ray pulses to investigate the temperature evolution of laser-shocked Al–Zr metal film composites at time delays ranging from 5 to 75 ns driven by a 120-ps short-pulse laser. We found significant heating of both Al and Zr after shock release, which can be attributed to heat generated by inelastic deformation. A conventional hydrodynamic model that employs (i) typical descriptions of Al and Zr mechanical strength and (ii) elevated strength responses (which might be attributed to an unknown strain rate dependence) did not fully account for the measured temperature increase, which suggests that other strength-related mechanisms (such as fine-scale void growth) could play an important role in thermal responses under shock wave loading/unloading cycles. Our results suggest that a significant portion of the total shock energy delivered by lasers becomes heat due to defect-facilitated plastic work, leaving less converted to kinetic energy. This heating effect may be common in laser-shocked experiments but has not been well acknowledged. High post-shock temperatures may induce phase transformation of materials during shock release. Another implication for the study is the preservability of magnetic records from planetary surfaces that have a shock history from frequent impact events.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940803","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}
Martin Moško, Mária Koscelanská, Antónia Mošková, Marek Vidiš, Serhii Volkov, Maroš Gregor, Magdaléna Poláčková, Tomáš Roch, Branislav Grančič, Leonid Satrapinskyy, Peter Kúš, Andrej Plecenik, Tomáš Plecenik
A thin TiO2 semiconductor film embedded between two metal electrodes works as a memristor after being formed by soft breakdown. The forming creates a nano-filament that penetrates through the poorly conducting TiO2 film and connects the electrodes conductively. While previous works characterized the nano-filament properties (shape, composition, and resistivity) by electron microscopy techniques, we present a characterization by electrical measurements. In a typical memristor, both electrodes are made of normal metals. We study the metal/TiO2/metal memristors with a bottom electrode made of a superconducting NbN layer and a top electrode made of a normal (Pt) or superconducting (Nb) metal. The nano-filament connecting the electrodes touches the bottom electrode as a point contact, thus allowing us to perform point-contact Andreev reflection spectroscopy of the NbN superconductor. The spectra, measured below the critical temperature (15 K) of NbN, are analyzed theoretically. The analysis reveals the presence of one nano-filament and determines the nano-filament resistance, Sharvin resistance of the point contact, and Maxwell resistance of the electrodes. Moreover, it shows that the nano-filament is a conical-shaped Ti-like metal point contact with a tip diameter of ∼3–5 nm, Fermi velocity of 2×106m/s, and low-temperature resistivity of ∼10−8–10−7Ωm. Thus, the nano-filament in our device is not the Ti4O7 phase observed in previous works. Remarkably, the point contact spectrum of the superconducting NbN layer shows the Andreev peak typical for ballistic transport. This is because the point contact probes the NbN layer through a thin Al layer that mimics superconductivity of NbN via the proximity effect and eliminates the effects of tunneling and disorder.
{"title":"Observation and characterization of titanium-like nano-filament in TiO2 memristor using superconducting electrode(s) and Andreev spectroscopy","authors":"Martin Moško, Mária Koscelanská, Antónia Mošková, Marek Vidiš, Serhii Volkov, Maroš Gregor, Magdaléna Poláčková, Tomáš Roch, Branislav Grančič, Leonid Satrapinskyy, Peter Kúš, Andrej Plecenik, Tomáš Plecenik","doi":"10.1063/5.0221209","DOIUrl":"https://doi.org/10.1063/5.0221209","url":null,"abstract":"A thin TiO2 semiconductor film embedded between two metal electrodes works as a memristor after being formed by soft breakdown. The forming creates a nano-filament that penetrates through the poorly conducting TiO2 film and connects the electrodes conductively. While previous works characterized the nano-filament properties (shape, composition, and resistivity) by electron microscopy techniques, we present a characterization by electrical measurements. In a typical memristor, both electrodes are made of normal metals. We study the metal/TiO2/metal memristors with a bottom electrode made of a superconducting NbN layer and a top electrode made of a normal (Pt) or superconducting (Nb) metal. The nano-filament connecting the electrodes touches the bottom electrode as a point contact, thus allowing us to perform point-contact Andreev reflection spectroscopy of the NbN superconductor. The spectra, measured below the critical temperature (15 K) of NbN, are analyzed theoretically. The analysis reveals the presence of one nano-filament and determines the nano-filament resistance, Sharvin resistance of the point contact, and Maxwell resistance of the electrodes. Moreover, it shows that the nano-filament is a conical-shaped Ti-like metal point contact with a tip diameter of ∼3–5 nm, Fermi velocity of 2×106m/s, and low-temperature resistivity of ∼10−8–10−7Ωm. Thus, the nano-filament in our device is not the Ti4O7 phase observed in previous works. Remarkably, the point contact spectrum of the superconducting NbN layer shows the Andreev peak typical for ballistic transport. This is because the point contact probes the NbN layer through a thin Al layer that mimics superconductivity of NbN via the proximity effect and eliminates the effects of tunneling and disorder.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940635","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}
O. Steuer, D. Schwarz, M. Oehme, F. Bärwolf, Y. Cheng, F. Ganss, R. Hübner, R. Heller, S. Zhou, M. Helm, G. Cuniberti, Y. M. Georgiev, S. Prucnal
Ge1−xSnx and Si1−x−yGeySnx alloys are promising materials for future opto- and nanoelectronics applications. These alloys enable effective bandgap engineering, broad adjustability of their lattice parameter, exhibit much higher carrier mobility than pure Si, and are compatible with the complementary metal-oxide-semiconductor technology. Unfortunately, the equilibrium solid solubility of Sn in Si1−xGex is less than 1% and the pseudomorphic growth of Si1−x−yGeySnx on Ge or Si can cause in-plane compressive strain in the grown layer, degrading the superior properties of these alloys. Therefore, post-growth strain engineering by ultrafast non-equilibrium thermal treatments like pulse laser annealing (PLA) is needed to improve the layer quality. In this article, Ge0.94Sn0.06 and Si0.14Ge0.8Sn0.06 thin films grown on silicon-on-insulator substrates by molecular beam epitaxy were post-growth thermally treated by PLA. The material is analyzed before and after the thermal treatments by transmission electron microscopy, x-ray diffraction (XRD), Rutherford backscattering spectrometry, secondary ion mass spectrometry, and Hall-effect measurements. It is shown that after annealing, the material is single-crystalline with improved crystallinity than the as-grown layer. This is reflected in a significantly increased XRD reflection intensity, well-ordered atomic pillars, and increased active carrier concentrations up to 4 × 1019 cm−3.
{"title":"Structural changes in Ge1−xSnx and Si1−x−yGeySnx thin films on SOI substrates treated by pulse laser annealing","authors":"O. Steuer, D. Schwarz, M. Oehme, F. Bärwolf, Y. Cheng, F. Ganss, R. Hübner, R. Heller, S. Zhou, M. Helm, G. Cuniberti, Y. M. Georgiev, S. Prucnal","doi":"10.1063/5.0218703","DOIUrl":"https://doi.org/10.1063/5.0218703","url":null,"abstract":"Ge1−xSnx and Si1−x−yGeySnx alloys are promising materials for future opto- and nanoelectronics applications. These alloys enable effective bandgap engineering, broad adjustability of their lattice parameter, exhibit much higher carrier mobility than pure Si, and are compatible with the complementary metal-oxide-semiconductor technology. Unfortunately, the equilibrium solid solubility of Sn in Si1−xGex is less than 1% and the pseudomorphic growth of Si1−x−yGeySnx on Ge or Si can cause in-plane compressive strain in the grown layer, degrading the superior properties of these alloys. Therefore, post-growth strain engineering by ultrafast non-equilibrium thermal treatments like pulse laser annealing (PLA) is needed to improve the layer quality. In this article, Ge0.94Sn0.06 and Si0.14Ge0.8Sn0.06 thin films grown on silicon-on-insulator substrates by molecular beam epitaxy were post-growth thermally treated by PLA. The material is analyzed before and after the thermal treatments by transmission electron microscopy, x-ray diffraction (XRD), Rutherford backscattering spectrometry, secondary ion mass spectrometry, and Hall-effect measurements. It is shown that after annealing, the material is single-crystalline with improved crystallinity than the as-grown layer. This is reflected in a significantly increased XRD reflection intensity, well-ordered atomic pillars, and increased active carrier concentrations up to 4 × 1019 cm−3.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141940804","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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