P. H. Beoletto, F. Nistri, A. S. Gliozzi, N. M. Pugno, F. Bosia
Many works in elasticity have exploited the concept of gradient index (GRIN) lenses, borrowed from optics, for wave focusing and control. These effects are particularly attractive for cloaking, absorption or energy harvesting applications. Despite their potential, current lens designs suffer from limitations, mainly related to the difficulty in imaging point-like sources. Here, we exploit an alternative GRIN lens design, which enables a one-to-one correspondence between input and output phase, and allows to determine the focal length using the well-known thin lens equation, effectively establishing the elastic equivalent of the convex lens in optics. This is demonstrated analytically, obtaining a bijective relation between the location of a point-like source and its image, and the results are confirmed numerically and experimentally in an aluminium plate, where the lens is realized by introducing rows of circular cavities of variable diameters. Moreover, a proof-of-concept experiment demonstrates the possibility to image sources of flexural waves at the centimetre scale with subwavelength resolution. This research can extend applications of elastic GRIN lenses to new fields such as imaging and non-destructive testing, where the location of defects can be identified by focusing the scattered field. Multiple sources can be imaged simultaneously, and the combined effect of multiple lenses can also be used to design more complex systems, opening new possibilities in the technological exploitation of elastic wave manipulation.
{"title":"The thin lens equation in elasticity: imaging with gradient index phononic crystals","authors":"P. H. Beoletto, F. Nistri, A. S. Gliozzi, N. M. Pugno, F. Bosia","doi":"arxiv-2409.01964","DOIUrl":"https://doi.org/arxiv-2409.01964","url":null,"abstract":"Many works in elasticity have exploited the concept of gradient index (GRIN)\u0000lenses, borrowed from optics, for wave focusing and control. These effects are\u0000particularly attractive for cloaking, absorption or energy harvesting\u0000applications. Despite their potential, current lens designs suffer from\u0000limitations, mainly related to the difficulty in imaging point-like sources.\u0000Here, we exploit an alternative GRIN lens design, which enables a one-to-one\u0000correspondence between input and output phase, and allows to determine the\u0000focal length using the well-known thin lens equation, effectively establishing\u0000the elastic equivalent of the convex lens in optics. This is demonstrated\u0000analytically, obtaining a bijective relation between the location of a\u0000point-like source and its image, and the results are confirmed numerically and\u0000experimentally in an aluminium plate, where the lens is realized by introducing\u0000rows of circular cavities of variable diameters. Moreover, a proof-of-concept\u0000experiment demonstrates the possibility to image sources of flexural waves at\u0000the centimetre scale with subwavelength resolution. This research can extend\u0000applications of elastic GRIN lenses to new fields such as imaging and\u0000non-destructive testing, where the location of defects can be identified by\u0000focusing the scattered field. Multiple sources can be imaged simultaneously,\u0000and the combined effect of multiple lenses can also be used to design more\u0000complex systems, opening new possibilities in the technological exploitation of\u0000elastic wave manipulation.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177810","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}
Michal Kaufman, Jaroslav Vlcek, Jiri Houska, Sadoon Farrukh, Stanislav Haviar
We report strongly thermochromic YSZ/V0.855W0.018Sr0.127O2/SiO2 coatings, where YSZ is Y stabilized ZrO2, prepared using a scalable deposition technique on standard glass at a low substrate temperature of 320 {deg}C and without any substrate bias voltage. The coatings exhibit a transition temperature of 22 {deg}C with an integral luminous transmittance of 63.7% (low-temperature state) and 60.7% (high-temperature state), and a modulation of the solar energy transmittance of 11.2%. Such a combination of properties, together with the low deposition temperature, fulfill the requirements for large-scale implementation on building glass and have not been reported yet. Reactive high-power impulse magnetron sputtering with a pulsed O2 flow feedback control allows us to prepare crystalline W and Sr co-doped VO2 of the correct stoichiometry. The W doping of VO2 decreases the transition temperature, while the Sr doping of VO2 increases the luminous transmittance significantly. A coating design utilizing a second-order interference in two antireflection layers is used to maximize both the integral luminous transmittance and the modulation of the solar energy transmittance. A compact crystalline structure of the bottom YSZ antireflection layer further improves the VO2 crystallinity, while the top SiO2 antireflection layer provides also the mechanical and environmental protection for the V0.855W0.018Sr0.127O2 layer.
我们报告了强热致变色YSZ/V0.855W0.018Sr0.127O2/SiO2涂层（其中YSZ是Y稳定的ZrO2），该涂层是在320{/deg}C的低基底温度和无任何基底偏置电压条件下，采用可扩展的沉积技术在标准玻璃上制备的。涂层的转变温度为 22{/deg}C，整体透光率为 63.7%（低温态）和 60.7%（高温态），太阳能传输调制率为 11.2%。这样的性能组合，加上较低的沉积温度，满足了在建筑玻璃上大规模应用的要求，目前还没有相关报道。通过脉冲氧气流反馈控制的反应式高功率脉冲磁控溅射，我们制备出了具有正确化学计量的 W 和 Sr 共掺杂结晶 VO2。VO2 的 W 掺杂降低了转变温度，而 VO2 的 Sr 掺杂则显著提高了透光率。利用两个抗反射层中的二阶干涉进行涂层设计，可最大限度地提高整体透光率和太阳能传输调制。底部 YSZ 减反射层的紧凑结晶结构进一步提高了 VO2 的结晶度，而顶部 SiO2 减反射层还为 V0.855W0.018Sr0.127O2 层提供了机械和环境保护。
{"title":"Design and Scalable Synthesis of Thermochromic VO2-Based Coatings for Energy-Saving Smart Windows with Exceptional Optical Performance","authors":"Michal Kaufman, Jaroslav Vlcek, Jiri Houska, Sadoon Farrukh, Stanislav Haviar","doi":"arxiv-2409.01745","DOIUrl":"https://doi.org/arxiv-2409.01745","url":null,"abstract":"We report strongly thermochromic YSZ/V0.855W0.018Sr0.127O2/SiO2 coatings,\u0000where YSZ is Y stabilized ZrO2, prepared using a scalable deposition technique\u0000on standard glass at a low substrate temperature of 320 {deg}C and without any\u0000substrate bias voltage. The coatings exhibit a transition temperature of 22\u0000{deg}C with an integral luminous transmittance of 63.7% (low-temperature\u0000state) and 60.7% (high-temperature state), and a modulation of the solar energy\u0000transmittance of 11.2%. Such a combination of properties, together with the low\u0000deposition temperature, fulfill the requirements for large-scale implementation\u0000on building glass and have not been reported yet. Reactive high-power impulse\u0000magnetron sputtering with a pulsed O2 flow feedback control allows us to\u0000prepare crystalline W and Sr co-doped VO2 of the correct stoichiometry. The W\u0000doping of VO2 decreases the transition temperature, while the Sr doping of VO2\u0000increases the luminous transmittance significantly. A coating design utilizing\u0000a second-order interference in two antireflection layers is used to maximize\u0000both the integral luminous transmittance and the modulation of the solar energy\u0000transmittance. A compact crystalline structure of the bottom YSZ antireflection\u0000layer further improves the VO2 crystallinity, while the top SiO2 antireflection\u0000layer provides also the mechanical and environmental protection for the\u0000V0.855W0.018Sr0.127O2 layer.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177811","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}
Aref Ghorbani, Sophia Jennie Giancoli, Seyed Ali Ghoreishy, Martijn Noort, Mehdi Habibi
We present a 3D food printing (3DFP) method to create coiled structures, harnessing the liquid rope coiling effect as a rapid method of food printing with tunable fractural properties. By studying the printability and coil-forming ability of pea, carrot, and cookie dough inks, we identified optimal printing parameters to induce steady and controlled coiling, enabling the creation of coiled structures with tunable porosities using a single nozzle. Fracture profiles from post-processed coiled structures showed complex responses but presented direct correlations between the porosity and textural parameters, including hardness, brittleness, and initial stiffness. This study provides a foundation for the fabrication of coiled food structures using 3DFP and highlights its potential application in designing textural properties and a range of unique sensory experiences.
{"title":"A novel 3D food printing technique: achieving tunable porosity and fracture properties via liquid rope coiling","authors":"Aref Ghorbani, Sophia Jennie Giancoli, Seyed Ali Ghoreishy, Martijn Noort, Mehdi Habibi","doi":"arxiv-2409.01487","DOIUrl":"https://doi.org/arxiv-2409.01487","url":null,"abstract":"We present a 3D food printing (3DFP) method to create coiled structures,\u0000harnessing the liquid rope coiling effect as a rapid method of food printing\u0000with tunable fractural properties. By studying the printability and\u0000coil-forming ability of pea, carrot, and cookie dough inks, we identified\u0000optimal printing parameters to induce steady and controlled coiling, enabling\u0000the creation of coiled structures with tunable porosities using a single\u0000nozzle. Fracture profiles from post-processed coiled structures showed complex\u0000responses but presented direct correlations between the porosity and textural\u0000parameters, including hardness, brittleness, and initial stiffness. This study\u0000provides a foundation for the fabrication of coiled food structures using 3DFP\u0000and highlights its potential application in designing textural properties and a\u0000range of unique sensory experiences.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177827","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}
Multi-layered materials are everywhere, from fiber-reinforced polymer composites (FRPCs) to plywood sheets to layered rocks. When in service, these materials are often exposed to long-term environmental factors, like moisture, temperature, salinity, etc. Moisture, in particular, is known to cause significant degradation of materials like polymers, often resulting in loss of material durability. Hence, it is critical to determine the total diffusion coefficient of multi-layered materials given the coefficients of individual layers. However, the relationship between a multi-layered material's total diffusion coefficient and the individual layers' diffusion coefficients is not well established. Existing parallel and series models to determine the total diffusion coefficient do not account for the order of layer stacking. In this paper, we introduce three parameters influencing the diffusion behavior of multi-layered materials: the ratio of diffusion coefficients of individual layers, the volume fraction of individual layers, and the stacking order of individual layers. Computational models are developed within a finite element method framework to conduct parametric analysis considering the proposed parameters. We propose a new model to calculate the total diffusion coefficient of multi-layered materials more accurately than current models. We verify this parametric study by performing moisture immersion experiments on multi-layered materials. Finally, we propose a methodology for designing and optimizing the cross-section of multi-layered materials considering long-term moisture resistance. This study gives new insights into the diffusion behavior of multi-layered materials, focusing on polymer composites.
{"title":"Moisture Diffusion in Multi-Layered Materials: The Role of Layer Stacking and Composition","authors":"Shaojie Zhang, Yuhao Liu, Peng Feng, Pavana Prabhakar","doi":"arxiv-2409.01150","DOIUrl":"https://doi.org/arxiv-2409.01150","url":null,"abstract":"Multi-layered materials are everywhere, from fiber-reinforced polymer\u0000composites (FRPCs) to plywood sheets to layered rocks. When in service, these\u0000materials are often exposed to long-term environmental factors, like moisture,\u0000temperature, salinity, etc. Moisture, in particular, is known to cause\u0000significant degradation of materials like polymers, often resulting in loss of\u0000material durability. Hence, it is critical to determine the total diffusion\u0000coefficient of multi-layered materials given the coefficients of individual\u0000layers. However, the relationship between a multi-layered material's total\u0000diffusion coefficient and the individual layers' diffusion coefficients is not\u0000well established. Existing parallel and series models to determine the total\u0000diffusion coefficient do not account for the order of layer stacking. In this\u0000paper, we introduce three parameters influencing the diffusion behavior of\u0000multi-layered materials: the ratio of diffusion coefficients of individual\u0000layers, the volume fraction of individual layers, and the stacking order of\u0000individual layers. Computational models are developed within a finite element\u0000method framework to conduct parametric analysis considering the proposed\u0000parameters. We propose a new model to calculate the total diffusion coefficient\u0000of multi-layered materials more accurately than current models. We verify this\u0000parametric study by performing moisture immersion experiments on multi-layered\u0000materials. Finally, we propose a methodology for designing and optimizing the\u0000cross-section of multi-layered materials considering long-term moisture\u0000resistance. This study gives new insights into the diffusion behavior of\u0000multi-layered materials, focusing on polymer composites.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223492","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}
Heavy computational demands from artificial intelligence (AI) leads the research community to explore the design space for functional materials that can be used for high performance memory and neuromorphic computing hardware. Novel device technologies with specially engineered properties are under intense investigation to revolutionize information processing with brain-inspired computing primitives for ultra energy-efficient implementation of AI and machine learning tasks. Ferroelectric memories with ultra-low power and fast operation, non-volatile data retention and reliable switching to multiple polarization states promises one such option for non-volatile memory and synaptic weight elements in neuromorphic hardware. For quick adaptation of industry, new materials need complementary metal oxide semiconductor (CMOS) process compatibility which brings a whole new set of challenges and opportunities for advanced materials design. In this work, we report on designing of back-end-of-line compatible ferroelectric Hf0.5Zr0.5O2 capacitors that are capable of recovery from fatigue multiple times reaching 2Pr > 40 microC cm-2 upon each retrieval. Our results indicate that with specifically engineered material stack and annealing protocols, it is possible to reach endurance exceeding 10^9 cycles at room temperature that can lead to ultralow power ferroelectric non-volatile memory components or synaptic weight elements compatible with online training or inference tasks for neuromorphic computing.
{"title":"Designing high endurance Hf0.5Zr0.5O2 capacitors through engineered recovery from fatigue for non-volatile ferroelectric memory and neuromorphic hardware","authors":"Xinye Li, Padma Srivari, Sayani Majumdar","doi":"arxiv-2409.00635","DOIUrl":"https://doi.org/arxiv-2409.00635","url":null,"abstract":"Heavy computational demands from artificial intelligence (AI) leads the\u0000research community to explore the design space for functional materials that\u0000can be used for high performance memory and neuromorphic computing hardware.\u0000Novel device technologies with specially engineered properties are under\u0000intense investigation to revolutionize information processing with\u0000brain-inspired computing primitives for ultra energy-efficient implementation\u0000of AI and machine learning tasks. Ferroelectric memories with ultra-low power\u0000and fast operation, non-volatile data retention and reliable switching to\u0000multiple polarization states promises one such option for non-volatile memory\u0000and synaptic weight elements in neuromorphic hardware. For quick adaptation of\u0000industry, new materials need complementary metal oxide semiconductor (CMOS)\u0000process compatibility which brings a whole new set of challenges and\u0000opportunities for advanced materials design. In this work, we report on\u0000designing of back-end-of-line compatible ferroelectric Hf0.5Zr0.5O2 capacitors\u0000that are capable of recovery from fatigue multiple times reaching 2Pr > 40\u0000microC cm-2 upon each retrieval. Our results indicate that with specifically\u0000engineered material stack and annealing protocols, it is possible to reach\u0000endurance exceeding 10^9 cycles at room temperature that can lead to ultralow\u0000power ferroelectric non-volatile memory components or synaptic weight elements\u0000compatible with online training or inference tasks for neuromorphic computing.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177829","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}
The advancement of next-generation magnetic devices depends on fast manipulating magnetic microstructures on the nanoscale. A universal method is presented for rapidly and reliably generating, controlling, and driving nano-scale skyrmioniums, through high-throughput micromagnetic simulations. Ultrafast switches are realized between skyrmionium and skyrmion states and rapidly change their polarities in monolayer magnetic nanodiscs by perpendicular magnetic fields. The transition mechanism by alternating magnetic fields differs from that under steady magnetic fields. New skyrmionic textures, such as flower-like and windmill-like skyrmions, are discovered. Moreover, this nanoscale skyrmionium can move rapidly and stably in nanoribbons using weaker spin-polarized currents. Explicit discussions are held regarding the physical mechanisms involved in ultrafast manipulations of skyrmioniums. This work provides further physical insight into the manipulation and applications of topological skyrmionic structures for developing low-power consumption and nanostorage devices.
{"title":"Ultrafast manipulations of nanoscale skyrmioniums","authors":"Haiming Dong, Panpan Fu, Yifeng Duan, Kai Chang","doi":"arxiv-2409.00683","DOIUrl":"https://doi.org/arxiv-2409.00683","url":null,"abstract":"The advancement of next-generation magnetic devices depends on fast\u0000manipulating magnetic microstructures on the nanoscale. A universal method is\u0000presented for rapidly and reliably generating, controlling, and driving\u0000nano-scale skyrmioniums, through high-throughput micromagnetic simulations.\u0000Ultrafast switches are realized between skyrmionium and skyrmion states and\u0000rapidly change their polarities in monolayer magnetic nanodiscs by\u0000perpendicular magnetic fields. The transition mechanism by alternating magnetic\u0000fields differs from that under steady magnetic fields. New skyrmionic textures,\u0000such as flower-like and windmill-like skyrmions, are discovered. Moreover, this\u0000nanoscale skyrmionium can move rapidly and stably in nanoribbons using weaker\u0000spin-polarized currents. Explicit discussions are held regarding the physical\u0000mechanisms involved in ultrafast manipulations of skyrmioniums. This work\u0000provides further physical insight into the manipulation and applications of\u0000topological skyrmionic structures for developing low-power consumption and\u0000nanostorage devices.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177828","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}
This work demonstrates high-performance vertical NiO/Ga2O3 heterojunction diodes (HJDs) with a 2-step space-modulated junction termination extension. Distinct from the current state-of-the-art Ga2O3 HJDs, we achieve breakdown voltage exceeding 3 kV with a low turn on voltage (VON) of 0.8V, estimated at a forward current density (IF) of 1 A-cm-2. The measured devices exhibit excellent turn-on characteristics achieving 100 A-cm-2 current density at a forward bias of 1.5V along with a low differential specific on-resistance (Ron,sp) of 4.4 m{Omega}-cm2. The SM-JTE was realized using concentric NiO rings with varying widths and spacing that approximates a gradual reduction in JTE charge. The unipolar figure of merit (FOM) calculated exceeds 2 GW-cm2 and is among the best reported for devices with a sub-1V turn-on. The fabricated devices also displayed minimal change in forward I-V characteristics post reverse bias stress of 3 kV applied during breakdown voltage testing.
{"title":">3kV NiO/Ga2O3 Heterojunction Diodes with Space-Modulated Junction Termination Extension and Sub-1V Turn-on","authors":"Advait Gilankar, Abishek Katta, Nabasindhu Das, Nidhin Kurian Kalarickal","doi":"arxiv-2409.00344","DOIUrl":"https://doi.org/arxiv-2409.00344","url":null,"abstract":"This work demonstrates high-performance vertical NiO/Ga2O3 heterojunction\u0000diodes (HJDs) with a 2-step space-modulated junction termination extension.\u0000Distinct from the current state-of-the-art Ga2O3 HJDs, we achieve breakdown\u0000voltage exceeding 3 kV with a low turn on voltage (VON) of 0.8V, estimated at a\u0000forward current density (IF) of 1 A-cm-2. The measured devices exhibit\u0000excellent turn-on characteristics achieving 100 A-cm-2 current density at a\u0000forward bias of 1.5V along with a low differential specific on-resistance\u0000(Ron,sp) of 4.4 m{Omega}-cm2. The SM-JTE was realized using concentric NiO\u0000rings with varying widths and spacing that approximates a gradual reduction in\u0000JTE charge. The unipolar figure of merit (FOM) calculated exceeds 2 GW-cm2 and\u0000is among the best reported for devices with a sub-1V turn-on. The fabricated\u0000devices also displayed minimal change in forward I-V characteristics post\u0000reverse bias stress of 3 kV applied during breakdown voltage testing.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177814","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}
Altermagnetic (AM) materials have recently attracted significant interest due to the non-relativistic momentum-dependent spin splitting of their electronic band structure which may be useful for antiferromagnetic (AFM) spintronics. So far, however, most research studies have been focused on AM metals which can be utilized in spintronic devices, such as AFM tunnel junctions (AFMTJs). At the same time, AM insulators have remained largely unexplored in the realm of AFM spintronics. Here, we propose to employ AM insulators (AMIs) as efficient spin-filter materials. By analyzing the complex band structure of rutile-type altermagnets $MF_2$ ($M$ = $Fe, Co, Ni$), we demonstrate that the evanescent states in these AMIs exhibit spin- and momentum-dependent decay rates resulting in a substantial momentum-dependent spin polarization of the tunneling current. Using a model of spin-filter tunneling across a spin-dependent potential barrier, we estimate the TMR effect in spin-filter magnetic tunnel junctions (SF-MTJs) that include two magnetically decoupled $MF_2$ (001) barrier layers. We predict a sizable spin-filter TMR ratio of about 150-170% in SF-MTJs based on AMIs $CoF_2$ and $NiF_2$ if the Fermi energy is tuned to be close to the valence band maximum. Our results demonstrate that AMIs provide a viable alternative to conventional ferromagnetic or ferrimagnetic spin-filter materials, potentially advancing the development of next-generation AFM spintronic devices.
{"title":"Spin filtering with insulating altermagnets","authors":"Kartik Samanta, Ding-Fu Shao, Evgeny Y. Tsymbal","doi":"arxiv-2409.00195","DOIUrl":"https://doi.org/arxiv-2409.00195","url":null,"abstract":"Altermagnetic (AM) materials have recently attracted significant interest due\u0000to the non-relativistic momentum-dependent spin splitting of their electronic\u0000band structure which may be useful for antiferromagnetic (AFM) spintronics. So\u0000far, however, most research studies have been focused on AM metals which can be\u0000utilized in spintronic devices, such as AFM tunnel junctions (AFMTJs). At the\u0000same time, AM insulators have remained largely unexplored in the realm of AFM\u0000spintronics. Here, we propose to employ AM insulators (AMIs) as efficient\u0000spin-filter materials. By analyzing the complex band structure of rutile-type\u0000altermagnets $MF_2$ ($M$ = $Fe, Co, Ni$), we demonstrate that the evanescent\u0000states in these AMIs exhibit spin- and momentum-dependent decay rates resulting\u0000in a substantial momentum-dependent spin polarization of the tunneling current.\u0000Using a model of spin-filter tunneling across a spin-dependent potential\u0000barrier, we estimate the TMR effect in spin-filter magnetic tunnel junctions\u0000(SF-MTJs) that include two magnetically decoupled $MF_2$ (001) barrier layers.\u0000We predict a sizable spin-filter TMR ratio of about 150-170% in SF-MTJs based\u0000on AMIs $CoF_2$ and $NiF_2$ if the Fermi energy is tuned to be close to the\u0000valence band maximum. Our results demonstrate that AMIs provide a viable\u0000alternative to conventional ferromagnetic or ferrimagnetic spin-filter\u0000materials, potentially advancing the development of next-generation AFM\u0000spintronic devices.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177830","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}
Data rates and volume for mobile communication are ever-increasing with the growing number of users and connected devices. With the deployment of 5G and 6G on the horizon, wireless communication is advancing to higher frequencies and larger bandwidths enabling higher speeds and throughput. Current micro-acoustic resonator technology, a key component in radiofrequency front end filters, is struggling to keep pace with these developments. This work presents a novel acoustic resonator architecture enabling multi-frequency, low-loss, and wideband filtering for the 5G and future 6G bands located above 3 GHz. Thanks to the exceptional performance of these resonators, filters for the 5G n77 and n79 bands are demonstrated, exhibiting fractional bandwidths of 13% and 25% respectively with low insertion loss of around 1 dB. With its unique frequency scalability and wideband capabilities, the reported architecture offers a promising option for filtering and multiplexing in future mobile devices.
{"title":"Suspended lithium niobate acoustic resonators with buried electrodes for radiofrequency filtering","authors":"Silvan Stettler, Luis Guillermo Villanueva","doi":"arxiv-2408.17282","DOIUrl":"https://doi.org/arxiv-2408.17282","url":null,"abstract":"Data rates and volume for mobile communication are ever-increasing with the\u0000growing number of users and connected devices. With the deployment of 5G and 6G\u0000on the horizon, wireless communication is advancing to higher frequencies and\u0000larger bandwidths enabling higher speeds and throughput. Current micro-acoustic\u0000resonator technology, a key component in radiofrequency front end filters, is\u0000struggling to keep pace with these developments. This work presents a novel\u0000acoustic resonator architecture enabling multi-frequency, low-loss, and\u0000wideband filtering for the 5G and future 6G bands located above 3 GHz. Thanks\u0000to the exceptional performance of these resonators, filters for the 5G n77 and\u0000n79 bands are demonstrated, exhibiting fractional bandwidths of 13% and 25%\u0000respectively with low insertion loss of around 1 dB. With its unique frequency\u0000scalability and wideband capabilities, the reported architecture offers a\u0000promising option for filtering and multiplexing in future mobile devices.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177832","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}
The buried interface between the electron transport layer and the perovskite layer suffers from severe interface defects and imperfect energy level alignment. To address this issue, this study employs a multifunctional organic molecule, curcumin, to modify the interface between SnO2 and the perovskite layer. The functional groups on curcumin effectively passivate the defects on both sides of the interface, reducing -OH and oxygen vacancy defects on the SnO2 surface and passivating uncoordinated Pb2+ in the perovskite layer. This results in a more compatible energy level alignment and lower defect density at the interface, enhancing carrier transport across it. Consequently, the devices based on curcumin achieve an impressive champion power conversion efficiency (PCE) of 24.46%, compared to 22.03% for control devices. This work demonstrates a simple, green, hydrophobic, and efficient molecular modification method for the buried interface, laying the foundation for the development of high-performance and stable perovskite solar cells.
{"title":"Highly Efficient and Stable Perovskite Solar Cells via MultiFunctional Curcumin Modified Buried Interface","authors":"Xianhu Wu, Jieyu Bi, Guanglei Cu, Nian Liu, Gaojie Xia, Jilong Sun, Jiaxin Jiang, Ning Lu, Ping Li, Chunyi Zhao, Zewen Zuo, Min Gu","doi":"arxiv-2408.17167","DOIUrl":"https://doi.org/arxiv-2408.17167","url":null,"abstract":"The buried interface between the electron transport layer and the perovskite\u0000layer suffers from severe interface defects and imperfect energy level\u0000alignment. To address this issue, this study employs a multifunctional organic\u0000molecule, curcumin, to modify the interface between SnO2 and the perovskite\u0000layer. The functional groups on curcumin effectively passivate the defects on\u0000both sides of the interface, reducing -OH and oxygen vacancy defects on the\u0000SnO2 surface and passivating uncoordinated Pb2+ in the perovskite layer. This\u0000results in a more compatible energy level alignment and lower defect density at\u0000the interface, enhancing carrier transport across it. Consequently, the devices\u0000based on curcumin achieve an impressive champion power conversion efficiency\u0000(PCE) of 24.46%, compared to 22.03% for control devices. This work demonstrates\u0000a simple, green, hydrophobic, and efficient molecular modification method for\u0000the buried interface, laying the foundation for the development of\u0000high-performance and stable perovskite solar cells.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177835","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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