Robotic stacking of van der Waals heterostructures has been at the verge, thanks to the convergence between artificial intelligence (AI) and two-dimensional (2D) materials research. Key ingredients to fulfill this pursuit often include algorithms to identify layer compounds on chips, hardwares to realize sophisticated operations of motion and/or rotation in a microscale, and, as importantly, highly standardized and uniform transfer stamps that are often used in picking up layered materials under a microscope. Here, we report a hot-cast-droplet batch fabrication method for polydimethylsiloxane (PDMS) templates tailored for dry transfer of 2D materials. Controlled precursor formulation, degassing, and motorized-syringe dispensing produce dome-shaped PDMS templates with ultra-smooth surfaces (root mean square roughness ∼0.3 nm at relatively low curing temperatures). By tuning the curing temperature, the reproducible and controllable apex curvature allows precisely defined contact area between the organic adhesive film and the substrate, via thermal expansion. Our results further reveal thermomechanical behaviors with different casting parameters of such PDMS domes. The capability of achieving defect-free van der Waals interfaces is further demonstrated by the fabrication of a high-quality BN/graphene/BN stack via dry transfer using the as-prepared PDMS templates. This scalable and parameterized fabrication protocol gives rise to uniform transfer stamps with ultra-smooth surface, which may be beneficial for future AI-driven robotic assembly of 2D material heterostructures.
{"title":"Batch-fabricated PDMS templates for the robotic transfer of 2D materials","authors":"Zhili Lin, Luosha Han, Jinkun He, Xiaoxue Fan, Tongyao Zhang, Xiaoxi Li, Baojuan Dong, Kai Zhao","doi":"10.1063/5.0311513","DOIUrl":"https://doi.org/10.1063/5.0311513","url":null,"abstract":"Robotic stacking of van der Waals heterostructures has been at the verge, thanks to the convergence between artificial intelligence (AI) and two-dimensional (2D) materials research. Key ingredients to fulfill this pursuit often include algorithms to identify layer compounds on chips, hardwares to realize sophisticated operations of motion and/or rotation in a microscale, and, as importantly, highly standardized and uniform transfer stamps that are often used in picking up layered materials under a microscope. Here, we report a hot-cast-droplet batch fabrication method for polydimethylsiloxane (PDMS) templates tailored for dry transfer of 2D materials. Controlled precursor formulation, degassing, and motorized-syringe dispensing produce dome-shaped PDMS templates with ultra-smooth surfaces (root mean square roughness ∼0.3 nm at relatively low curing temperatures). By tuning the curing temperature, the reproducible and controllable apex curvature allows precisely defined contact area between the organic adhesive film and the substrate, via thermal expansion. Our results further reveal thermomechanical behaviors with different casting parameters of such PDMS domes. The capability of achieving defect-free van der Waals interfaces is further demonstrated by the fabrication of a high-quality BN/graphene/BN stack via dry transfer using the as-prepared PDMS templates. This scalable and parameterized fabrication protocol gives rise to uniform transfer stamps with ultra-smooth surface, which may be beneficial for future AI-driven robotic assembly of 2D material heterostructures.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"77 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
We report the magnetotransport properties of zirconium pentatelluride (ZrTe5) in the Dirac semimetal phase, focusing on its magnetoresistance behavior at low temperatures. Pronounced Shubnikov–de Haas oscillations were observed in the low magnetic field regime. In the quantum limit, linear magnetoresistance and behavior consistent with a topological phase transition emerge. In-depth analyses of these phenomena and their temperature dependences suggest that both the chemical potential and the Fermi velocity may play an important role in determining the transport properties of ZrTe5 in the quantum limit. Our findings highlight the importance of band parameters in topological transport and provide insights for future studies of topological materials and the design of quantum devices.
{"title":"Magnetotransport properties of Dirac semimetal ZrTe5 in the quantum limit","authors":"Fa-Hua Chen, Sheng-Zong Chen, Pin-Chi Liao, Wei-Chen Lin, Po-Shao Lai, Pi-Ju Shih, Jeng-Chung Chen, Limin Cao, Chi-Te Liang","doi":"10.1063/5.0310211","DOIUrl":"https://doi.org/10.1063/5.0310211","url":null,"abstract":"We report the magnetotransport properties of zirconium pentatelluride (ZrTe5) in the Dirac semimetal phase, focusing on its magnetoresistance behavior at low temperatures. Pronounced Shubnikov–de Haas oscillations were observed in the low magnetic field regime. In the quantum limit, linear magnetoresistance and behavior consistent with a topological phase transition emerge. In-depth analyses of these phenomena and their temperature dependences suggest that both the chemical potential and the Fermi velocity may play an important role in determining the transport properties of ZrTe5 in the quantum limit. Our findings highlight the importance of band parameters in topological transport and provide insights for future studies of topological materials and the design of quantum devices.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"127 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Xue Bai, Siyuan Lu, Xinyue Wang, Jianhui Chang, Qiming Lei, Fawad Aslam, Long Fang, Mustafa Haider, Nadia Shahzad, Hengyue Li, Junliang Yang
Perovskite solar cells (PSCs), recognized for their high efficiency and scalable manufacturing potential, face significant challenges in achieving uniform, high-quality large-area films via ambient doctor-blading techniques, particularly due to limitations in conventional solvent systems. This study addresses the critical need for solvent systems capable of serving as viable alternatives to conventional solvent, while simultaneously optimizing crystallization kinetics and film morphology under ambient conditions. We demonstrate a N, N-dimethylformamide (DMF)-free co-solvent strategy utilizing 2-methoxyethanol (2-ME) and N-methyl-2-pyrrolidone (NMP) to precisely modulate solvent evaporation dynamics and perovskite nucleation. The weak coordination of Pb2+ by 2-ME promotes rapid volatilization, while the strong coordination by NMP stabilizes the intermediates and delays surface nucleation, enabling uniform crystallization and dense films formation. The optimized NMP improved crystallinity, reduced non-radiative recombination, and boosted charge transport, enhancing power conversion efficiency (PCE) from 20.18% to 23.43%. Furthermore, a mini-module (10.3 cm2) fabricated under the same conditions achieved a PCE of 19.08%, underscoring the scalability and applicability of the proposed approach. These findings suggest that the DMF-free co-solvent strategy is highly effective for the scalable fabrication of large-area PSC modules and offers a promising pathway toward their commercialization.
{"title":"DMF-free co-solvent doctor-bladed FA0.6MA0.4PbI3 perovskite solar cells and modules under ambient conditions","authors":"Xue Bai, Siyuan Lu, Xinyue Wang, Jianhui Chang, Qiming Lei, Fawad Aslam, Long Fang, Mustafa Haider, Nadia Shahzad, Hengyue Li, Junliang Yang","doi":"10.1063/5.0297564","DOIUrl":"https://doi.org/10.1063/5.0297564","url":null,"abstract":"Perovskite solar cells (PSCs), recognized for their high efficiency and scalable manufacturing potential, face significant challenges in achieving uniform, high-quality large-area films via ambient doctor-blading techniques, particularly due to limitations in conventional solvent systems. This study addresses the critical need for solvent systems capable of serving as viable alternatives to conventional solvent, while simultaneously optimizing crystallization kinetics and film morphology under ambient conditions. We demonstrate a N, N-dimethylformamide (DMF)-free co-solvent strategy utilizing 2-methoxyethanol (2-ME) and N-methyl-2-pyrrolidone (NMP) to precisely modulate solvent evaporation dynamics and perovskite nucleation. The weak coordination of Pb2+ by 2-ME promotes rapid volatilization, while the strong coordination by NMP stabilizes the intermediates and delays surface nucleation, enabling uniform crystallization and dense films formation. The optimized NMP improved crystallinity, reduced non-radiative recombination, and boosted charge transport, enhancing power conversion efficiency (PCE) from 20.18% to 23.43%. Furthermore, a mini-module (10.3 cm2) fabricated under the same conditions achieved a PCE of 19.08%, underscoring the scalability and applicability of the proposed approach. These findings suggest that the DMF-free co-solvent strategy is highly effective for the scalable fabrication of large-area PSC modules and offers a promising pathway toward their commercialization.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"33 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Sihua Guo, Minghe Wang, Si Chen, Kristoffer Harr, Yong Zhang, Yan Zhang, Bin Wei, Johan Liu
To enhance the thermal management capabilities of epoxy composite, inspired by Baumkuchen, a simple, scalable, and environmentally friendly process was proposed. The graphene strips, without any chemical modification, were integrated into assembled graphene paper, and the vertically aligned graphene strips/epoxy composite with the tree-ring structure was prepared by the rolling cutting method. The composite exhibited an extremely high through-plane thermal conductivity of 49.2 W/mK, which was 289 times higher than that of pure EP. Additionally, the composite also possesses a range of desirable properties, including good electromagnetic interference shielding, efficient Joule heating, and remarkable mechanical performance. These properties further expand the application of graphene-based thermal interface materials in the field of thermal management of electronic devices.
{"title":"Graphene-based thermal interface materials with high through-plane thermal conductivity inspired by Baumkuchen","authors":"Sihua Guo, Minghe Wang, Si Chen, Kristoffer Harr, Yong Zhang, Yan Zhang, Bin Wei, Johan Liu","doi":"10.1063/5.0310419","DOIUrl":"https://doi.org/10.1063/5.0310419","url":null,"abstract":"To enhance the thermal management capabilities of epoxy composite, inspired by Baumkuchen, a simple, scalable, and environmentally friendly process was proposed. The graphene strips, without any chemical modification, were integrated into assembled graphene paper, and the vertically aligned graphene strips/epoxy composite with the tree-ring structure was prepared by the rolling cutting method. The composite exhibited an extremely high through-plane thermal conductivity of 49.2 W/mK, which was 289 times higher than that of pure EP. Additionally, the composite also possesses a range of desirable properties, including good electromagnetic interference shielding, efficient Joule heating, and remarkable mechanical performance. These properties further expand the application of graphene-based thermal interface materials in the field of thermal management of electronic devices.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Altermagnets, which arise from the alternating crystal environment and have spontaneous spin-splitting with zero net magnetization, provide a unique opportunity for potential spintronics or valleytronics. Here, we predict two types of stable altermagnets, the Fe2WS4 monolayer and the Janus Fe2WS2Se2 monolayer, based on density functional theory calculations. It is revealed that both monolayers are found to be altermagnetic semiconductors with the valence band maximum and conduction band minimum locating around the high-symmetry point X or Y. Moreover, the altermagnetic order of Fe atom sublattices is related to M110 mirror symmetry. Under uniaxial strains, both monolayers can generate obvious valley polarization and spin polarization due to the broken of the mirror symmetry. Such piezovalley effect in Fe2WS4 and Janus Fe2WS2Se2 monolayers facilitates the design of low-power spintronic devices for information encoding.
{"title":"Piezovalley effect in altermagnetic Fe2WS4 and Fe2WS2Se2 monolayers","authors":"Yinong Liu, Jiahui Li, Huijie Lian, Xiaojing Yao, Xiuyun Zhang","doi":"10.1063/5.0305258","DOIUrl":"https://doi.org/10.1063/5.0305258","url":null,"abstract":"Altermagnets, which arise from the alternating crystal environment and have spontaneous spin-splitting with zero net magnetization, provide a unique opportunity for potential spintronics or valleytronics. Here, we predict two types of stable altermagnets, the Fe2WS4 monolayer and the Janus Fe2WS2Se2 monolayer, based on density functional theory calculations. It is revealed that both monolayers are found to be altermagnetic semiconductors with the valence band maximum and conduction band minimum locating around the high-symmetry point X or Y. Moreover, the altermagnetic order of Fe atom sublattices is related to M110 mirror symmetry. Under uniaxial strains, both monolayers can generate obvious valley polarization and spin polarization due to the broken of the mirror symmetry. Such piezovalley effect in Fe2WS4 and Janus Fe2WS2Se2 monolayers facilitates the design of low-power spintronic devices for information encoding.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"26 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Xin Cao, Zichao Rong, Chao Wang, Yi Xu, Xiangyu Hu, Zhongshu Feng, Mingzhang Wei, Zhou Li, Zhengyu Xiao, Yongda Chen, Yi Zheng, Guchang Han, Tiejun Zhou, Bo Liu
High critical switching current density (Jc) and limited charge-to-spin conversion efficiency [spin–orbit torque (SOT) efficiency, ξSOT] of heavy metal-based SOT channels are the two key challenges for the development of energy-efficient SOT magnetic random-access memory (SOT-MRAM). In this paper, we demonstrate a significant enhancement of SOT efficiency in β-tungsten (W) films through magnesium oxide (MgO) doping, achieved via co-sputtering (CS) and multilayer-heterostructure (MLH) deposition, respectively. The W/MgO nanostructures retain the β-phase and exhibit a remarkable increase in ξSOT, from 0.20 in pure W to 0.48 for CS films (4% MgO doping)—and even more impressively—to 0.51 for the MLH method. The drastic SOT efficiency improvement is attributed primarily to the significantly enhanced skew scattering induced by MgO incorporation. As direct performance gauges, Jc of W/MgO nanostructures is reduced by up to 50.6%, and the power consumption is lowered by over 42%, compared to pure W-based devices. These findings highlight W/MgO nanostructures as highly promising SOT channel materials for energy-efficient SOT-MRAM applications.
{"title":"Giant spin–orbit torques in W/MgO nanostructures for energy-efficient SOT-MRAM applications","authors":"Xin Cao, Zichao Rong, Chao Wang, Yi Xu, Xiangyu Hu, Zhongshu Feng, Mingzhang Wei, Zhou Li, Zhengyu Xiao, Yongda Chen, Yi Zheng, Guchang Han, Tiejun Zhou, Bo Liu","doi":"10.1063/5.0307470","DOIUrl":"https://doi.org/10.1063/5.0307470","url":null,"abstract":"High critical switching current density (Jc) and limited charge-to-spin conversion efficiency [spin–orbit torque (SOT) efficiency, ξSOT] of heavy metal-based SOT channels are the two key challenges for the development of energy-efficient SOT magnetic random-access memory (SOT-MRAM). In this paper, we demonstrate a significant enhancement of SOT efficiency in β-tungsten (W) films through magnesium oxide (MgO) doping, achieved via co-sputtering (CS) and multilayer-heterostructure (MLH) deposition, respectively. The W/MgO nanostructures retain the β-phase and exhibit a remarkable increase in ξSOT, from 0.20 in pure W to 0.48 for CS films (4% MgO doping)—and even more impressively—to 0.51 for the MLH method. The drastic SOT efficiency improvement is attributed primarily to the significantly enhanced skew scattering induced by MgO incorporation. As direct performance gauges, Jc of W/MgO nanostructures is reduced by up to 50.6%, and the power consumption is lowered by over 42%, compared to pure W-based devices. These findings highlight W/MgO nanostructures as highly promising SOT channel materials for energy-efficient SOT-MRAM applications.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"52 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
High-temperature capacitive energy storage demands dielectric polymers that integrate high thermal conductivity with excellent electrical insulation to mitigate thermal runaway induced by Joule heating. However, conventional strategies for improving thermal conductivity through increased aromatic conjugation frequently exacerbate conductive losses under elevated temperatures and high electric fields. To resolve this fundamental trade-off between thermal conductivity and electrical insulation, we introduce a conjugation-decoupling strategy. This approach incorporates aliphatic segments to disrupt the π–π conjugation networks, implemented through a machine learning-assisted co-design workflow. A transfer learning model is built to establish the structure–property relationship between glass transition temperature and thermal conductivity, and subsequently guides the synthesis of three semi-aromatic polyimides that concurrently achieve a high glass transition temperature, a wide bandgap, and high thermal conductivity. The resulting semi-alicyclic polyimide film demonstrated outstanding discharge energy density (5.26 J cm−3) and η = 90% performance at 200 °C, significantly outperforming commercial Kapton polyimide film. We report a strategy for high-temperature dielectric development using an interpretable machine learning model, demonstrating a concurrent enhancement of electrical insulation and thermal conductivity, properties typically constrained by a conventional trade-off.
{"title":"Breaking the thermal–dielectric trade-off in high-temperature polymers via transfer learning","authors":"Ruo-Jie Cheng, Dong-Duan Liu, Qiao Li, Yu-Jie Zhu, Feng Wang, Hongxiao Yang, Qian Zhou, Chao Yuan","doi":"10.1063/5.0307269","DOIUrl":"https://doi.org/10.1063/5.0307269","url":null,"abstract":"High-temperature capacitive energy storage demands dielectric polymers that integrate high thermal conductivity with excellent electrical insulation to mitigate thermal runaway induced by Joule heating. However, conventional strategies for improving thermal conductivity through increased aromatic conjugation frequently exacerbate conductive losses under elevated temperatures and high electric fields. To resolve this fundamental trade-off between thermal conductivity and electrical insulation, we introduce a conjugation-decoupling strategy. This approach incorporates aliphatic segments to disrupt the π–π conjugation networks, implemented through a machine learning-assisted co-design workflow. A transfer learning model is built to establish the structure–property relationship between glass transition temperature and thermal conductivity, and subsequently guides the synthesis of three semi-aromatic polyimides that concurrently achieve a high glass transition temperature, a wide bandgap, and high thermal conductivity. The resulting semi-alicyclic polyimide film demonstrated outstanding discharge energy density (5.26 J cm−3) and η = 90% performance at 200 °C, significantly outperforming commercial Kapton polyimide film. We report a strategy for high-temperature dielectric development using an interpretable machine learning model, demonstrating a concurrent enhancement of electrical insulation and thermal conductivity, properties typically constrained by a conventional trade-off.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"43 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Lead-free sodium bismuth titanate and related compounds are promising piezoelectric materials. A comprehensive understanding of this series of materials remains a challenge, partly due to their structural complexity and the differences in structure and properties caused by the application of an external electric field. This study investigates the effect of doping Bi2Ti2O7 (BTO) into 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (BNT-6BT) ceramics. The results show that the introduction of BTO increases the pseudo-cubic phase structure of BNT-6BT and breaks the ferroelectric long-range order to form more polar nanoregions. The composition induces a phase transition from the ferroelectric phase to the relaxor phase, in which oxygen vacancies may play a certain role, and the relaxor property of the ceramics is enhanced. The BNT-6BT-4wt%BTO ceramic achieves a high positive strain (0.43%) at room temperature, which is attributed to the huge strain generated during the reversible transition between the ergodic relaxor phase and the long-range ordered ferroelectric phase. Overall, BTO doping significantly modifies the properties of BNT-6BT ceramics, enabling them to exhibit reversible long-range ordered transitions under an electric field, thus providing potential for applications in precision actuators.
{"title":"Bi2Ti2O7 modification-induced large strain characteristics in BNT-6BT piezoelectric ceramics","authors":"Zhenhua Lu, Wenwei Ge, Shaonan Xu, Xiaojuan Liu, Liang Li, Qiang Shi, Qinhui Zhang","doi":"10.1063/5.0314093","DOIUrl":"https://doi.org/10.1063/5.0314093","url":null,"abstract":"Lead-free sodium bismuth titanate and related compounds are promising piezoelectric materials. A comprehensive understanding of this series of materials remains a challenge, partly due to their structural complexity and the differences in structure and properties caused by the application of an external electric field. This study investigates the effect of doping Bi2Ti2O7 (BTO) into 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (BNT-6BT) ceramics. The results show that the introduction of BTO increases the pseudo-cubic phase structure of BNT-6BT and breaks the ferroelectric long-range order to form more polar nanoregions. The composition induces a phase transition from the ferroelectric phase to the relaxor phase, in which oxygen vacancies may play a certain role, and the relaxor property of the ceramics is enhanced. The BNT-6BT-4wt%BTO ceramic achieves a high positive strain (0.43%) at room temperature, which is attributed to the huge strain generated during the reversible transition between the ergodic relaxor phase and the long-range ordered ferroelectric phase. Overall, BTO doping significantly modifies the properties of BNT-6BT ceramics, enabling them to exhibit reversible long-range ordered transitions under an electric field, thus providing potential for applications in precision actuators.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"18 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Arjun Sapkota, Pukar Sedai, Robert M. Klaes, Reza Loloee, Norman O. Birge, Nathan Satchell
We report large π-state critical current densities, Jc(π), in Nb/Pd89Ni11/Nb Josephson junctions at Pd89Ni11 thicknesses near the first π-state. We observe oscillations in the critical current with ferromagnetic barrier thickness consistent with a 0–π transition. For a junction with a 9.4 nm Pd89Ni11 barrier, we obtain Jc(π)=410 kA/cm2 at 4.2 K, exceeding values reported in prior PdNi-based studies. Magnetization measurements on continuous films, together with coercivity tests on patterned arrays, confirm that Pd89Ni11 exhibits perpendicular magnetic anisotropy, enabling zero-field operation without magnetic initialization. The combination of large Jc(π) and intrinsic anisotropy establishes Pd89Ni11 as a promising barrier material for passive π-shifters in superconducting digital logic and qubit architectures.
{"title":"Large critical current density Josephson π -junctions with PdNi barriers","authors":"Arjun Sapkota, Pukar Sedai, Robert M. Klaes, Reza Loloee, Norman O. Birge, Nathan Satchell","doi":"10.1063/5.0317028","DOIUrl":"https://doi.org/10.1063/5.0317028","url":null,"abstract":"We report large π-state critical current densities, Jc(π), in Nb/Pd89Ni11/Nb Josephson junctions at Pd89Ni11 thicknesses near the first π-state. We observe oscillations in the critical current with ferromagnetic barrier thickness consistent with a 0–π transition. For a junction with a 9.4 nm Pd89Ni11 barrier, we obtain Jc(π)=410 kA/cm2 at 4.2 K, exceeding values reported in prior PdNi-based studies. Magnetization measurements on continuous films, together with coercivity tests on patterned arrays, confirm that Pd89Ni11 exhibits perpendicular magnetic anisotropy, enabling zero-field operation without magnetic initialization. The combination of large Jc(π) and intrinsic anisotropy establishes Pd89Ni11 as a promising barrier material for passive π-shifters in superconducting digital logic and qubit architectures.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"267 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
Takashi Teranishi, Kanji Uefuji, Shinya Kondo, Shintaro Yasui, Akira Kishimoto
The use of copper (Cu) electrodes in multilayer ceramic capacitors (MLCCs) is highly attractive due to its low cost and electrical resistivity compared with nickel (Ni). However, Cu easily oxidizes and diffuses into BaTiO3 (BT) during high-temperature sintering, degrading dielectric properties and breakdown strength. In this study, 24 GHz millimeter-wave (MMW) irradiation was employed to investigate and control Cu diffusion in BT ceramics. Pre-sintered dense BT was coated with Cu paste and subsequently heated either conventionally (Conv.) or under MMW irradiation at 950–1050 °C. MMW irradiation significantly suppressed Cu diffusion into BT, increasing the activation energy for diffusion from 282 to 340 kJ mol−1. Under Conv. heating, oxygen-vacancy accumulation stabilizes mixed-valence Cu states in the CuO grain-boundary phase, promoting long-range Cu diffusion. In contrast, enhanced oxygen-vacancy mobility under MMW irradiation suppresses such defect-rich states, resulting in reduced Cu diffusion. These results demonstrate that MMW irradiation provides a nonthermal pathway to selectively control cation diffusion, offering a promising strategy for developing reliable Cu-based MLCCs.
{"title":"Millimeter-wave control of copper diffusion in BaTiO3 for ceramic capacitors","authors":"Takashi Teranishi, Kanji Uefuji, Shinya Kondo, Shintaro Yasui, Akira Kishimoto","doi":"10.1063/5.0312900","DOIUrl":"https://doi.org/10.1063/5.0312900","url":null,"abstract":"The use of copper (Cu) electrodes in multilayer ceramic capacitors (MLCCs) is highly attractive due to its low cost and electrical resistivity compared with nickel (Ni). However, Cu easily oxidizes and diffuses into BaTiO3 (BT) during high-temperature sintering, degrading dielectric properties and breakdown strength. In this study, 24 GHz millimeter-wave (MMW) irradiation was employed to investigate and control Cu diffusion in BT ceramics. Pre-sintered dense BT was coated with Cu paste and subsequently heated either conventionally (Conv.) or under MMW irradiation at 950–1050 °C. MMW irradiation significantly suppressed Cu diffusion into BT, increasing the activation energy for diffusion from 282 to 340 kJ mol−1. Under Conv. heating, oxygen-vacancy accumulation stabilizes mixed-valence Cu states in the CuO grain-boundary phase, promoting long-range Cu diffusion. In contrast, enhanced oxygen-vacancy mobility under MMW irradiation suppresses such defect-rich states, resulting in reduced Cu diffusion. These results demonstrate that MMW irradiation provides a nonthermal pathway to selectively control cation diffusion, offering a promising strategy for developing reliable Cu-based MLCCs.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"104 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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