Pub Date : 2025-10-18DOI: 10.1016/j.cap.2025.10.010
Bongkeon Kim, Yong-Joo Doh
Superconducting coplanar waveguide (SCPW) resonators, key components for quantum computing and sensing applications, require a high internal quality factor (Qi) for effective qubit readout and quantum sensing applications. Minimizing two-level system (TLS) losses, particularly at material interfaces, is critical for gatemon and topological qubits operating at low temperatures and in high magnetic fields. NbTi, a superconducting alloy with a high upper critical field, enables SCPW resonators resilient to such conditions. We fabricated NbTi SCPW resonators on Si/SiO2 substrates and systematically characterized their TLS-limited quality factors as functions of temperature and microwave photon number. Our results demonstrate that NbTi-based SCPWs on Si/SiO2 substrates provide a promising platform for developing next-generation quantum circuits.
{"title":"Two-level system loss characterization of NbTi superconducting resonators on Si/SiO2 substrates","authors":"Bongkeon Kim, Yong-Joo Doh","doi":"10.1016/j.cap.2025.10.010","DOIUrl":"10.1016/j.cap.2025.10.010","url":null,"abstract":"<div><div>Superconducting coplanar waveguide (SCPW) resonators, key components for quantum computing and sensing applications, require a high internal quality factor (<em>Q</em><sub>i</sub>) for effective qubit readout and quantum sensing applications. Minimizing two-level system (TLS) losses, particularly at material interfaces, is critical for gatemon and topological qubits operating at low temperatures and in high magnetic fields. NbTi, a superconducting alloy with a high upper critical field, enables SCPW resonators resilient to such conditions. We fabricated NbTi SCPW resonators on Si/SiO<sub>2</sub> substrates and systematically characterized their TLS-limited quality factors as functions of temperature and microwave photon number. Our results demonstrate that NbTi-based SCPWs on Si/SiO<sub>2</sub> substrates provide a promising platform for developing next-generation quantum circuits.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"80 ","pages":"Pages 354-361"},"PeriodicalIF":3.1,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145358201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Pub Date : 2025-10-16DOI: 10.1016/j.cap.2025.10.009
Hae In Choi , Myang Hwan Lee , Won-Jeong Kim , Tae Kwon Song
The development of high-performance, lead-free piezoelectric ceramics is essential for modern sensor and actuator applications. Bismuth ferrite-based solid solutions, like (1-x)BiFeO3-xBaTiO3 (BF-BT), are promising due to their high Curie temperature and high piezoelectric performance, but ambiguities persist regarding their phase transitions and the exact location of the morphotropic phase boundary (MPB), where piezoelectric properties are maximized. This study resolves these issues by applying Landau-Devonshire theory to construct a comprehensive phase diagram for the BF-BT system. By calculating the free energy density landscape, our theoretical model accurately reproduces the material's composition-dependent properties. The resulting phase diagram agrees well with experimental observations, predicting a coexistence of rhombohedral and tetragonal phases near x = 0.33. And our calculations identify the MPB at a composition of x = 0.375, consistent with the experimentally reported range. These findings highlight the link between phase structure and piezoelectric performance.
{"title":"Landau-Devonshire theory-based phase diagram of the bismuth ferrite and barium titanate solid solution","authors":"Hae In Choi , Myang Hwan Lee , Won-Jeong Kim , Tae Kwon Song","doi":"10.1016/j.cap.2025.10.009","DOIUrl":"10.1016/j.cap.2025.10.009","url":null,"abstract":"<div><div>The development of high-performance, lead-free piezoelectric ceramics is essential for modern sensor and actuator applications. Bismuth ferrite-based solid solutions, like (1-<em>x</em>)BiFeO<sub>3</sub>-<em>x</em>BaTiO<sub>3</sub> (BF-BT), are promising due to their high Curie temperature and high piezoelectric performance, but ambiguities persist regarding their phase transitions and the exact location of the morphotropic phase boundary (MPB), where piezoelectric properties are maximized. This study resolves these issues by applying Landau-Devonshire theory to construct a comprehensive phase diagram for the BF-BT system. By calculating the free energy density landscape, our theoretical model accurately reproduces the material's composition-dependent properties. The resulting phase diagram agrees well with experimental observations, predicting a coexistence of rhombohedral and tetragonal phases near <em>x</em> = 0.33. And our calculations identify the MPB at a composition of <em>x</em> = 0.375, consistent with the experimentally reported range. These findings highlight the link between phase structure and piezoelectric performance.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"80 ","pages":"Pages 362-366"},"PeriodicalIF":3.1,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145358202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Pub Date : 2025-10-16DOI: 10.1016/j.cap.2025.10.006
Kyungmin Park, Garam Bae
Graphene field-effect transistors offer great potential for next-generation electronics due to graphene's high carrier mobility and atomic-scale thickness. However, stable device operation requires precise control of the dielectric interface, which impacts carrier transport and doping. In this study, we use solution-processed polysilazane (PSZ)-derived dielectrics as both gate insulators and active ionic environments for modulating graphene's electronic properties. The PSZ films, processed under humid conditions, generate hydroxyl-rich surfaces that serve as proton reservoirs. Electrical characterization and in-situ Raman spectroscopy show that gate bias induces proton doping of graphene, manifesting as hysteresis, Dirac point shifts, and D-band enhancement arising from phonon activation and interfacial Coulombic perturbations. The device also exhibits characteristic doping and relaxation times, revealing proton migration dynamics. Our findings suggest that PSZ dielectrics provide both gate insulation and dynamic electrochemical modulation of the graphene channel, offering a new strategy for dielectric interface engineering in 2D electronic devices.
{"title":"Proton doping of graphene FETs enabled by ionic modulation from polysilazane dielectrics","authors":"Kyungmin Park, Garam Bae","doi":"10.1016/j.cap.2025.10.006","DOIUrl":"10.1016/j.cap.2025.10.006","url":null,"abstract":"<div><div>Graphene field-effect transistors offer great potential for next-generation electronics due to graphene's high carrier mobility and atomic-scale thickness. However, stable device operation requires precise control of the dielectric interface, which impacts carrier transport and doping. In this study, we use solution-processed polysilazane (PSZ)-derived dielectrics as both gate insulators and active ionic environments for modulating graphene's electronic properties. The PSZ films, processed under humid conditions, generate hydroxyl-rich surfaces that serve as proton reservoirs. Electrical characterization and in-situ Raman spectroscopy show that gate bias induces proton doping of graphene, manifesting as hysteresis, Dirac point shifts, and D-band enhancement arising from phonon activation and interfacial Coulombic perturbations. The device also exhibits characteristic doping and relaxation times, revealing proton migration dynamics. Our findings suggest that PSZ dielectrics provide both gate insulation and dynamic electrochemical modulation of the graphene channel, offering a new strategy for dielectric interface engineering in 2D electronic devices.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"80 ","pages":"Pages 346-353"},"PeriodicalIF":3.1,"publicationDate":"2025-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145358200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Pub Date : 2025-10-13DOI: 10.1016/j.cap.2025.10.005
Layla Mravac , Yi-De Chuang , Ji Hyeon Choi , Ji Won Han , Tae Joo Park , Kyung Won Park , Jae Hyuck Jang , Cheng-Tai Kuo , Deok-Yong Cho
Excess carriers in defective TiO2 play a key role in determining the functionality of numerous applications including photocatalysts, memristors, etc. The electronic structures of the excess electron states derived from inherent oxygen deficiencies in a TiO2 crystal and a TiO2 thin film are investigated by using resonant inelastic soft X-ray scattering. The results show that there exist two separable states associated with these excess electrons, that is, either local (bound) or delocalized (band-like) d electrons, and that their abundance differs significantly depending on the sample type. In the case of thin film, delocalized electron states (d-fluorescence) dominate over the localized defect states (dd excitation) showing a strong resonance effect at Ti3+’s excitation energy, whereas in the case of crystal, both localized and delocalized electron states weakly contribute to the defect states. Most plausibly, this discrepancy originates mainly from the distinct crystal structure of a rutile (crystal) and an anatase (thin film), implying that understanding the crystal structure dependence of intrinsic defects in TiO2 polymorphs is crucial for engineering TiO2's electronic transport properties.
{"title":"Localized and delocalized electron states in TiO2 revealed using resonant inelastic soft X-ray scattering","authors":"Layla Mravac , Yi-De Chuang , Ji Hyeon Choi , Ji Won Han , Tae Joo Park , Kyung Won Park , Jae Hyuck Jang , Cheng-Tai Kuo , Deok-Yong Cho","doi":"10.1016/j.cap.2025.10.005","DOIUrl":"10.1016/j.cap.2025.10.005","url":null,"abstract":"<div><div>Excess carriers in defective TiO<sub>2</sub> play a key role in determining the functionality of numerous applications including photocatalysts, memristors, etc. The electronic structures of the excess electron states derived from inherent oxygen deficiencies in a TiO<sub>2</sub> crystal and a TiO<sub>2</sub> thin film are investigated by using resonant inelastic soft X-ray scattering. The results show that there exist two separable states associated with these excess electrons, that is, either local (bound) or delocalized (band-like) <em>d</em> electrons, and that their abundance differs significantly depending on the sample type. In the case of thin film, delocalized electron states (<em>d</em>-fluorescence) dominate over the localized defect states (<em>dd</em> excitation) showing a strong resonance effect at Ti<sup>3+</sup>’s excitation energy, whereas in the case of crystal, both localized and delocalized electron states weakly contribute to the defect states. Most plausibly, this discrepancy originates mainly from the distinct crystal structure of a rutile (crystal) and an anatase (thin film), implying that understanding the crystal structure dependence of intrinsic defects in TiO<sub>2</sub> polymorphs is crucial for engineering TiO<sub>2</sub>'s electronic transport properties.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"80 ","pages":"Pages 327-332"},"PeriodicalIF":3.1,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145332807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
It is shown, that an ultra-low-power voltage controlled oscillator, realized with conventional NAND gates in ring-oscillator configuration, can be operated by a series connected pair of commercial Silicon pin solar cells, only irradiated by a high energy proton beam as power supply. However a very fast degradation of the solar cells is observed, leading to a stop of the oscillator operation after a very short time. By monitoring the oscillator frequency changes when the stack of photodiodes, in this case illuminated with weak ambient light, is not directly exposed to the proton beam but positioned in different positions close to the proton beam, an evaluation of the off-beam-axis irradiation damage could be done. A detailed electrical analysis of the photodiode properties before and after the direct proton irradiation has been added.
{"title":"A nanowatt oscillator powered only by 68 MeV proton irradiation of a crystalline silicon photodiode pair","authors":"Heinz-Christoph Neitzert , Arpana Singh , Alina Hanna Dittwald , Georgios Kourkafas","doi":"10.1016/j.cap.2025.10.004","DOIUrl":"10.1016/j.cap.2025.10.004","url":null,"abstract":"<div><div>It is shown, that an ultra-low-power voltage controlled oscillator, realized with conventional NAND gates in ring-oscillator configuration, can be operated by a series connected pair of commercial Silicon pin solar cells, only irradiated by a high energy proton beam as power supply. However a very fast degradation of the solar cells is observed, leading to a stop of the oscillator operation after a very short time. By monitoring the oscillator frequency changes when the stack of photodiodes, in this case illuminated with weak ambient light, is not directly exposed to the proton beam but positioned in different positions close to the proton beam, an evaluation of the off-beam-axis irradiation damage could be done. A detailed electrical analysis of the photodiode properties before and after the direct proton irradiation has been added.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"80 ","pages":"Pages 306-310"},"PeriodicalIF":3.1,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Pub Date : 2025-10-06DOI: 10.1016/j.cap.2025.10.002
Thi Bich Ngoc Nguyen , Thi Hong Nhung Vu , Anshula Tandon, Sungjin Lee, Yeonju Nam, Sung Ha Park
DNA-based algorithmic self-assembly provides a versatile platform for parallel computation and nanoscale pattern generation. Logic gates constructed from DNA rule tiles enable programmable lattices capable of performing complex mathematical operations. Here, we present a combinatorial method for generating diverse algorithmic patterns using 3-input 1-output logic rules. By combining complementary rule sets (e.g., {R017, R238}) and non-complementary sets (e.g., {R019, R238}), we designed specific rule and operator tiles that reduce the number of unique tiles required while expanding the range of implementable logic functions. The resulting DNA lattices were experimentally validated using atomic force microscopy, and observed patterns closely matched theoretical predictions, demonstrating high fidelity and reliability. This approach improves scalability and efficiency compared with conventional single-rule assemblies and provides a practical route toward constructing complex computational architectures at the nanoscale, with potential applications in molecular computing, programmable nanomaterials, and DNA-based information processing.
{"title":"Scalable assembly of algorithmic DNA lattices using combined 3-input logic rules","authors":"Thi Bich Ngoc Nguyen , Thi Hong Nhung Vu , Anshula Tandon, Sungjin Lee, Yeonju Nam, Sung Ha Park","doi":"10.1016/j.cap.2025.10.002","DOIUrl":"10.1016/j.cap.2025.10.002","url":null,"abstract":"<div><div>DNA-based algorithmic self-assembly provides a versatile platform for parallel computation and nanoscale pattern generation. Logic gates constructed from DNA rule tiles enable programmable lattices capable of performing complex mathematical operations. Here, we present a combinatorial method for generating diverse algorithmic patterns using 3-input 1-output logic rules. By combining complementary rule sets (e.g., {R017, R238}) and non-complementary sets (e.g., {R019, R238}), we designed specific rule and operator tiles that reduce the number of unique tiles required while expanding the range of implementable logic functions. The resulting DNA lattices were experimentally validated using atomic force microscopy, and observed patterns closely matched theoretical predictions, demonstrating high fidelity and reliability. This approach improves scalability and efficiency compared with conventional single-rule assemblies and provides a practical route toward constructing complex computational architectures at the nanoscale, with potential applications in molecular computing, programmable nanomaterials, and DNA-based information processing.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"80 ","pages":"Pages 333-340"},"PeriodicalIF":3.1,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145332808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Pub Date : 2025-10-02DOI: 10.1016/j.cap.2025.09.025
C.Y. Lee, J.H. Han, Y.S. Lee
We investigate the optical thermometric performance of Er3+-doped perovskite oxides with thermally coupled levels (TCLs). We obtain their optical thermometric parameters, such as their fluorescence intensity ratio and temperature sensitivity, from upconversion luminescence spectra under 980 nm excitation over a wide temperature range. Subsequently, we systematically compare these experimentally determined parameters with theoretical predictions for a TCL system, in addition to parameters derived from Judd–Ofelt (J–O) analysis, which is a well-established theoretical framework that describes the radiative transitions and intensities of rare-earth (RE) ions. A close correspondence between the experimental and theoretical results is achieved when the temperature-dependent variation of the J–O parameters and the TCL gap is considered. Our findings provide valuable insights into the roles of host-lattice effects, local crystal field variations, and defect-related phenomena in governing the thermal response of RE ion-doped phosphors for optical thermometry applications.
{"title":"Correlation between optical thermometry and Judd–Ofelt parameters in Er3+-doped perovskite oxides","authors":"C.Y. Lee, J.H. Han, Y.S. Lee","doi":"10.1016/j.cap.2025.09.025","DOIUrl":"10.1016/j.cap.2025.09.025","url":null,"abstract":"<div><div>We investigate the optical thermometric performance of Er<sup>3+</sup>-doped perovskite oxides with thermally coupled levels (TCLs). We obtain their optical thermometric parameters, such as their fluorescence intensity ratio and temperature sensitivity, from upconversion luminescence spectra under 980 nm excitation over a wide temperature range. Subsequently, we systematically compare these experimentally determined parameters with theoretical predictions for a TCL system, in addition to parameters derived from Judd–Ofelt (J–O) analysis, which is a well-established theoretical framework that describes the radiative transitions and intensities of rare-earth (RE) ions. A close correspondence between the experimental and theoretical results is achieved when the temperature-dependent variation of the J–O parameters and the TCL gap is considered. Our findings provide valuable insights into the roles of host-lattice effects, local crystal field variations, and defect-related phenomena in governing the thermal response of RE ion-doped phosphors for optical thermometry applications.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"80 ","pages":"Pages 265-272"},"PeriodicalIF":3.1,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145226938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Pub Date : 2025-10-02DOI: 10.1016/j.cap.2025.10.003
Ibrar Ahmad , Syeeda Nida Alim , Khizar Hayat , Abdullah Shah , Sabir Shah , Said Karim Shah
This study explores the impact of active layer (AL) thickness, annealing temperatures(ATs), and interfacial materials on the performance of polymer solar cells (PSCs) based on P3HT: PCBM. AL thickness was tuned by varying spin speeds (1000–5000 rpm), with devices D1K and D4K achieving PCEs of 2.37 % and 2.17 % after thermal annealing at 130 °C. Increasing the AT to 180 °C further enhanced device efficiency. The influence of interfacial layers LiF and Ca on PSC performance and thermal stability was also investigated. Ca/Al-based devices outperformed others at lower temperatures but degraded at higher temperatures, while LiF/Al-based devices showed reduced PCE beyond ∼110 °C. To complement experiments, simulations using drift-diffusion, exciton-diffusion, and transfer-matrix models(TMM) were performed. These provided insights into photon distribution, absorption, and carrier generation, supporting the experimental outcomes. The study offers a comprehensive understanding of the interplay between device architecture and thermal treatment in optimizing PSC performance.
{"title":"Experimental and computational insights into optimizing polymer solar cell operational parameters","authors":"Ibrar Ahmad , Syeeda Nida Alim , Khizar Hayat , Abdullah Shah , Sabir Shah , Said Karim Shah","doi":"10.1016/j.cap.2025.10.003","DOIUrl":"10.1016/j.cap.2025.10.003","url":null,"abstract":"<div><div>This study explores the impact of active layer (AL) thickness, annealing temperatures(ATs), and interfacial materials on the performance of polymer solar cells (PSCs) based on P3HT: PCBM. AL thickness was tuned by varying spin speeds (1000–5000 rpm), with devices D1K and D4K achieving PCEs of 2.37 % and 2.17 % after thermal annealing at 130 °C. Increasing the AT to 180 °C further enhanced device efficiency. The influence of interfacial layers LiF and Ca on PSC performance and thermal stability was also investigated. Ca/Al-based devices outperformed others at lower temperatures but degraded at higher temperatures, while LiF/Al-based devices showed reduced PCE beyond ∼110 °C. To complement experiments, simulations using drift-diffusion, exciton-diffusion, and transfer-matrix models(TMM) were performed. These provided insights into photon distribution, absorption, and carrier generation, supporting the experimental outcomes. The study offers a comprehensive understanding of the interplay between device architecture and thermal treatment in optimizing PSC performance.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"80 ","pages":"Pages 291-299"},"PeriodicalIF":3.1,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Pub Date : 2025-10-02DOI: 10.1016/j.cap.2025.10.001
Zhiyong Chen , Mengsi Liu , Shubo Cheng , Junqiao Wang , Yougen Yi , Boxun Li , Chaojun Tang , Fan Gao
The tunable terahertz perfect absorber based on a bilayer graphene metamaterial achieves breakthrough performance through an innovative design that combines a square array-box composite resonant cavity unit structure with dynamic Fermi level control. By adjusting the graphene Fermi level (0–0.5 eV), the absorption peak can dynamically switch from a single wide peak to a double-peak U-shaped depression, covering a tuning range of 3.99–8.91 THz. After optimization, the average absorption rate in the target frequency band reaches 97 %. This structure, through the synergistic mechanism of localized field enhancement and impedance matching, achieves the first active reconstruction of the absorption peak shape within a wide bandwidth (from a wide peak to a U-shaped peak), providing a new solution for terahertz stealth communication and high-sensitivity sensing.
{"title":"Bilayer graphene metasurface with dynamically reconfigurable terahertz perfect absorption","authors":"Zhiyong Chen , Mengsi Liu , Shubo Cheng , Junqiao Wang , Yougen Yi , Boxun Li , Chaojun Tang , Fan Gao","doi":"10.1016/j.cap.2025.10.001","DOIUrl":"10.1016/j.cap.2025.10.001","url":null,"abstract":"<div><div>The tunable terahertz perfect absorber based on a bilayer graphene metamaterial achieves breakthrough performance through an innovative design that combines a square array-box composite resonant cavity unit structure with dynamic Fermi level control. By adjusting the graphene Fermi level (0–0.5 eV), the absorption peak can dynamically switch from a single wide peak to a double-peak U-shaped depression, covering a tuning range of 3.99–8.91 THz. After optimization, the average absorption rate in the target frequency band reaches 97 %. This structure, through the synergistic mechanism of localized field enhancement and impedance matching, achieves the first active reconstruction of the absorption peak shape within a wide bandwidth (from a wide peak to a U-shaped peak), providing a new solution for terahertz stealth communication and high-sensitivity sensing.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"80 ","pages":"Pages 282-290"},"PeriodicalIF":3.1,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145262495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Pub Date : 2025-10-01DOI: 10.1016/j.cap.2025.09.028
Muhammad Arif , Donghun Han , Seunghun Cha , Changsun Pak , Young-Kwang Kim , Sang Woo Kim , Bo Wha Lee , Muhammad Awais , Dongwhi Choi , Jong-Soo Rhyee
Soft magnetic composites are essential to power electronics technologies, including transformers, motors, and generators. However, as electronic devices advance, SMCs should have excellent soft magnetic properties, such as high permeability, high saturation magnetization, and reduced core loss at high frequencies. In this study, we found exceptionally high soft magnetic properties for Co nanopowder distribution in Fe3O4-coated Fe SMCs prepared via the hot-pressing technique. Incorporating Co nano-powders leads to a notable increase in density, with the most compact structure observed in the sample containing the highest Co concentration. Electrical resistivity increases to 55.54 mΩ cm for a sample containing 1 wt% Co nanopowder, compared to 15 mΩ cm for a pristine sample. The SMCs exhibit excellent soft magnetic properties, with high saturation magnetization (Ms ∼216 emu/g), high permeability (μe∼237.42) (144 % higher than the undoped sample), high DC bias performance (71.45 % at 100 kOe), and reduced core loss (Pcv, Ph, and Pe), compared to the other state-of-the-art samples. It indicates that Fe/Fe3O4-Co SMCs are highly promising for miniaturization and high-energy efficiency of electronic components.
{"title":"Enhancement of soft magnetic properties in surface-oxidized Fe/Fe3O4 composites via Co-nanoparticle doping and hot pressing","authors":"Muhammad Arif , Donghun Han , Seunghun Cha , Changsun Pak , Young-Kwang Kim , Sang Woo Kim , Bo Wha Lee , Muhammad Awais , Dongwhi Choi , Jong-Soo Rhyee","doi":"10.1016/j.cap.2025.09.028","DOIUrl":"10.1016/j.cap.2025.09.028","url":null,"abstract":"<div><div>Soft magnetic composites are essential to power electronics technologies, including transformers, motors, and generators. However, as electronic devices advance, SMCs should have excellent soft magnetic properties, such as high permeability, high saturation magnetization, and reduced core loss at high frequencies. In this study, we found exceptionally high soft magnetic properties for Co nanopowder distribution in Fe<sub>3</sub>O<sub>4</sub>-coated Fe SMCs prepared via the hot-pressing technique. Incorporating Co nano-powders leads to a notable increase in density, with the most compact structure observed in the sample containing the highest Co concentration. Electrical resistivity increases to 55.54 mΩ cm for a sample containing 1 wt% Co nanopowder, compared to 15 mΩ cm for a pristine sample. The SMCs exhibit excellent soft magnetic properties, with high saturation magnetization (<em>M</em><sub>s</sub> ∼216 emu/g), high permeability (<em>μ</em><sub>e</sub>∼237.42) (144 % higher than the undoped sample), high DC bias performance (71.45 % at 100 kOe), and reduced core loss (<em>P</em><sub>cv</sub>, <em>P</em><sub>h</sub>, and <em>P</em><sub>e</sub>), compared to the other state-of-the-art samples. It indicates that Fe/Fe<sub>3</sub>O<sub>4</sub>-Co SMCs are highly promising for miniaturization and high-energy efficiency of electronic components.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"80 ","pages":"Pages 256-264"},"PeriodicalIF":3.1,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145226828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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