A. Fournier, N. Nilforoushan, I. Abdourahamane, D. Gacemi, J. Tignon, S. Dhillon, J.-B. Brubach, C. Taverna, P. Roy, Y. Prado, F. Carossella, R. Ferreira, E. Lhuillier, J. Mangeney
With their tunable intraband absorption in the THz range and carrier dynamics on the order of tens of picoseconds, large HgTe nanocrystals (NCs) hold strong potential for THz optoelectronic devices, including modulators and detectors. Their THz intraband absorption has been attributed to multiple transitions of single carriers between quantized states. However, since most investigations have been limited to room temperature, many fundamental physical questions remain open. Here, we investigate the THz intraband absorption in both linear and nonlinear regimes across a broad temperature range. Our results highlight the essential role of thermally activated carriers in the linear regime, which has been so far neglected in existing models, and show that nonlinear intraband absorption in large HgTe NCs arises from an increase in chemical potential combined with changes in electronic temperature, both influenced by saturation effects associated with the progressive filling of electronic states. Furthermore, using mid-infrared pump–THz probe experiments, we probe the carrier dynamics and demonstrate that surface traps and ligand modes have a negligible effect on hot carrier recombination. The dominant recombination pathway is attributed to non-radiative interband processes mediated by optical phonon emission. This work provides new insight into the physical mechanisms underlying the THz intraband absorption of HgTe NCs in both linear and nonlinear regimes, refines their theoretical description, and highlights the potential of large HgTe NCs for THz optoelectronic devices such as modulators and detectors.
{"title":"THz intraband absorption in HgTe nanocrystals in the linear and nonlinear regimes","authors":"A. Fournier, N. Nilforoushan, I. Abdourahamane, D. Gacemi, J. Tignon, S. Dhillon, J.-B. Brubach, C. Taverna, P. Roy, Y. Prado, F. Carossella, R. Ferreira, E. Lhuillier, J. Mangeney","doi":"10.1063/5.0308557","DOIUrl":"https://doi.org/10.1063/5.0308557","url":null,"abstract":"With their tunable intraband absorption in the THz range and carrier dynamics on the order of tens of picoseconds, large HgTe nanocrystals (NCs) hold strong potential for THz optoelectronic devices, including modulators and detectors. Their THz intraband absorption has been attributed to multiple transitions of single carriers between quantized states. However, since most investigations have been limited to room temperature, many fundamental physical questions remain open. Here, we investigate the THz intraband absorption in both linear and nonlinear regimes across a broad temperature range. Our results highlight the essential role of thermally activated carriers in the linear regime, which has been so far neglected in existing models, and show that nonlinear intraband absorption in large HgTe NCs arises from an increase in chemical potential combined with changes in electronic temperature, both influenced by saturation effects associated with the progressive filling of electronic states. Furthermore, using mid-infrared pump–THz probe experiments, we probe the carrier dynamics and demonstrate that surface traps and ligand modes have a negligible effect on hot carrier recombination. The dominant recombination pathway is attributed to non-radiative interband processes mediated by optical phonon emission. This work provides new insight into the physical mechanisms underlying the THz intraband absorption of HgTe NCs in both linear and nonlinear regimes, refines their theoretical description, and highlights the potential of large HgTe NCs for THz optoelectronic devices such as modulators and detectors.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"14611 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145770945","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}
Raghottam M. Sattigeri, Xujia Gong, Amar Fakhredine, Carmine Autieri, Giuseppe Cuono
Two-dimensional (2D) metallic altermagnets present exciting opportunities for both fundamental research and practical innovations. Their ability to enhance tunneling magnetoresistance in magnetic tunnel junctions, combined with the direct control of spin currents via electric fields, makes them highly promising for spintronic devices. Moreover, the rich electronic structure of altermagnets can host nontrivial topological phases. In particular, topological crystalline insulators are compounds where the topological states are protected by both crystalline and time-reversal symmetries. Furthermore, manipulating the state of a system between topological and trivial phases through external parameters unlocks new possibilities for quantum materials and advanced electronics. We show the edge states of a 2D metallic compound that displays signatures of an underlying altermagnetic topological crystalline phase, using as a representative example Cr2BAl, a 2D MBene metallic altermagnet with a dx2−y2 altermagnetic ordering. We find that the system can host an altermagnetic phase with extremely large “weak ferrimagnetism” which is sizeable also with light atoms, only with an in-plane component of the Néel vector. The electronic structure of Cr2BAl presents multiple crossings in the vicinity of the Fermi level along [100]- and [010]-directions. When the spin–orbit coupling interaction is included, with the Néel vector along [001]-direction, this results in a pronounced peak in the spin Hall conductivity. The simulated Cr–B terminated [100] edge-projected band structure reveals Dirac dispersions at the bulk crossings, which are absent in Cr–Al terminations.
{"title":"Dirac edge states as signature of two-dimensional altermagnetic topological crystalline phase","authors":"Raghottam M. Sattigeri, Xujia Gong, Amar Fakhredine, Carmine Autieri, Giuseppe Cuono","doi":"10.1063/5.0285433","DOIUrl":"https://doi.org/10.1063/5.0285433","url":null,"abstract":"Two-dimensional (2D) metallic altermagnets present exciting opportunities for both fundamental research and practical innovations. Their ability to enhance tunneling magnetoresistance in magnetic tunnel junctions, combined with the direct control of spin currents via electric fields, makes them highly promising for spintronic devices. Moreover, the rich electronic structure of altermagnets can host nontrivial topological phases. In particular, topological crystalline insulators are compounds where the topological states are protected by both crystalline and time-reversal symmetries. Furthermore, manipulating the state of a system between topological and trivial phases through external parameters unlocks new possibilities for quantum materials and advanced electronics. We show the edge states of a 2D metallic compound that displays signatures of an underlying altermagnetic topological crystalline phase, using as a representative example Cr2BAl, a 2D MBene metallic altermagnet with a dx2−y2 altermagnetic ordering. We find that the system can host an altermagnetic phase with extremely large “weak ferrimagnetism” which is sizeable also with light atoms, only with an in-plane component of the Néel vector. The electronic structure of Cr2BAl presents multiple crossings in the vicinity of the Fermi level along [100]- and [010]-directions. When the spin–orbit coupling interaction is included, with the Néel vector along [001]-direction, this results in a pronounced peak in the spin Hall conductivity. The simulated Cr–B terminated [100] edge-projected band structure reveals Dirac dispersions at the bulk crossings, which are absent in Cr–Al terminations.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"17 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759833","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}
Helium, a scarce gas, is widely used in various fields, like aerospace, semiconductor manufacturing, biomedicine, etc. However, the detection of helium leakage remains challenging because helium is an inert gas with exceptional chemical stability, and, thus, traditional gas sensors working with gas absorption cannot be applied in helium sensing. In this work, we create a helium sensor on the basis of an acoustic topological material, which works with the shift of topological corner states and does not rely on chemical absorption. The sensor is created with a two-dimensional Kagome structure, producing corner states at three corners. Theoretical analysis and experimental measurement demonstrate that the sensor possesses a constant relative sensitivity, which is marginally influenced by working conditions. As a result, the sensor can be applied in extremely wide ranges of temperature and humidity and does not require calibration. Furthermore, three corner states arising at distinct positions are adopted to orientate the leakage point. Additionally, because of topological protection, the corner states are marginally influenced by defects in the sensor, and, thus, multiple and large gas input holes are allowed to considerably speed up the response and recovery of the sensor. The sensor exhibits good stability, repeatability, and rapid response without basement shift in helium detection and is available in the detection of various inert gases. Meanwhile, this work provides insights into the application of two-dimensional acoustic topological materials.
{"title":"A sensor for helium leakage detection and orientation based on a two-dimensional acoustic topological material","authors":"Zhao-yi Wang, Zhan-tao Zhou, Li Fan, Xiao-dong Xu, Li-ping Cheng, Shu-yi Zhang","doi":"10.1063/5.0288849","DOIUrl":"https://doi.org/10.1063/5.0288849","url":null,"abstract":"Helium, a scarce gas, is widely used in various fields, like aerospace, semiconductor manufacturing, biomedicine, etc. However, the detection of helium leakage remains challenging because helium is an inert gas with exceptional chemical stability, and, thus, traditional gas sensors working with gas absorption cannot be applied in helium sensing. In this work, we create a helium sensor on the basis of an acoustic topological material, which works with the shift of topological corner states and does not rely on chemical absorption. The sensor is created with a two-dimensional Kagome structure, producing corner states at three corners. Theoretical analysis and experimental measurement demonstrate that the sensor possesses a constant relative sensitivity, which is marginally influenced by working conditions. As a result, the sensor can be applied in extremely wide ranges of temperature and humidity and does not require calibration. Furthermore, three corner states arising at distinct positions are adopted to orientate the leakage point. Additionally, because of topological protection, the corner states are marginally influenced by defects in the sensor, and, thus, multiple and large gas input holes are allowed to considerably speed up the response and recovery of the sensor. The sensor exhibits good stability, repeatability, and rapid response without basement shift in helium detection and is available in the detection of various inert gases. Meanwhile, this work provides insights into the application of two-dimensional acoustic topological materials.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"56 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145770587","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}
In LC multi-parameter sensors, coil mutual inductance induces crosstalk, causing resonant shifts and signal interference. This study proposes a reverse adjacent coil structure that generates opposing magnetic fields to suppress mutual inductance and reduce crosstalk. A theoretical coplanar inductance model was established, with a derived mutual inductance formula and applicable conditions. Coplanar inductor behavior was analyzed via HFSS simulations, and two LC circuits were constructed to examine dual-resonant interactions. Experiments validated the model by varying two capacitor values and fabricating capacitive sensors. This passive method preserves signal independence and accuracy while reducing complexity. It is well-suited for thin-film wireless sensing, enabling precise and reliable synchronous measurements.
{"title":"LC dual-parameter coplanar coil decoupling method based on reverse adjacent coil structure design","authors":"Dezhao Wang, Xin Li, Qingkai Han, Shujun Ma, Guanlin Guo, Xiang He","doi":"10.1063/5.0294561","DOIUrl":"https://doi.org/10.1063/5.0294561","url":null,"abstract":"In LC multi-parameter sensors, coil mutual inductance induces crosstalk, causing resonant shifts and signal interference. This study proposes a reverse adjacent coil structure that generates opposing magnetic fields to suppress mutual inductance and reduce crosstalk. A theoretical coplanar inductance model was established, with a derived mutual inductance formula and applicable conditions. Coplanar inductor behavior was analyzed via HFSS simulations, and two LC circuits were constructed to examine dual-resonant interactions. Experiments validated the model by varying two capacitor values and fabricating capacitive sensors. This passive method preserves signal independence and accuracy while reducing complexity. It is well-suited for thin-film wireless sensing, enabling precise and reliable synchronous measurements.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759830","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}
The significant optimization of electric field distribution for AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT) with a thick i-GaN cap layer is reported. The thick i-GaN cap layer is introduced to generate two-dimensional hole gas (2DHG), thereby reducing the electron concentration in the two-dimensional electron gas (2DEG) layer under off-state, in contrast to the high electron concentration in the 2DEG layer under off-state for the MIS-HEMT with a p-type or insulating passivation layer. Due to the low electron concentration in the 2DEG layer and the introduction of the thick i-GaN cap layer, a wide depletion region forms in this cap layer just close to the drain electrode under off-state, resulting in a low electric field intensity both in the whole access region and in the region close to the gate. Thus, the adverse effect induced by the high electric field strength under off-state, such as the large dynamic on-resistance (Ron), is significantly mitigated.
{"title":"Optimization of electric field distribution for AlGaN/GaN MIS-HEMT with thick i-GaN cap layer","authors":"Kangyao Wen, Chenkai Deng, Yuhan Sun, Qing Wang, Yu-Long Jiang, HongYu Yu","doi":"10.1063/5.0299082","DOIUrl":"https://doi.org/10.1063/5.0299082","url":null,"abstract":"The significant optimization of electric field distribution for AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT) with a thick i-GaN cap layer is reported. The thick i-GaN cap layer is introduced to generate two-dimensional hole gas (2DHG), thereby reducing the electron concentration in the two-dimensional electron gas (2DEG) layer under off-state, in contrast to the high electron concentration in the 2DEG layer under off-state for the MIS-HEMT with a p-type or insulating passivation layer. Due to the low electron concentration in the 2DEG layer and the introduction of the thick i-GaN cap layer, a wide depletion region forms in this cap layer just close to the drain electrode under off-state, resulting in a low electric field intensity both in the whole access region and in the region close to the gate. Thus, the adverse effect induced by the high electric field strength under off-state, such as the large dynamic on-resistance (Ron), is significantly mitigated.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"46 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759828","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}
With the growing demand for low-power and high-speed spintronic devices, the development of advanced material systems with efficient spin control capabilities has emerged as a central focus in spintronics research. Here, we propose a fully antiferromagnetic device architecture based on a magnetically compensated RuO2/synthetic antiferromagnet heterostructure, achieving fully electrical writing and reading functionalities. This design, characterized by its negligible stray field and deterministic field-free switching, is inherently suitable for large-scale neuromorphic integration. In a proof-of-concept demonstration, we showcase the implementation of an all-spintronic convolutional neural network using this architecture, achieving a high recognition accuracy of 98.7% on the handwritten digit classification task.
{"title":"Spin-splitting-torque-driven field-free perpendicular magnetization switching in RuO2/synthetic antiferromagnet heterostructures for spintronic convolutional neural networks","authors":"Qian Wang, Yibo Fan, Fubin Chen, Chuanwei Feng, Dong Wang, Yiheng Wang, Zhenxing Wang, Lihui Bai, Xinglong Ye, Yufeng Tian, Shishen Yan","doi":"10.1063/5.0306696","DOIUrl":"https://doi.org/10.1063/5.0306696","url":null,"abstract":"With the growing demand for low-power and high-speed spintronic devices, the development of advanced material systems with efficient spin control capabilities has emerged as a central focus in spintronics research. Here, we propose a fully antiferromagnetic device architecture based on a magnetically compensated RuO2/synthetic antiferromagnet heterostructure, achieving fully electrical writing and reading functionalities. This design, characterized by its negligible stray field and deterministic field-free switching, is inherently suitable for large-scale neuromorphic integration. In a proof-of-concept demonstration, we showcase the implementation of an all-spintronic convolutional neural network using this architecture, achieving a high recognition accuracy of 98.7% on the handwritten digit classification task.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"56 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759827","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}
Ultrafast laser excitation offers a powerful means to modulate material properties on femtosecond timescales. Here, we investigate croconic acid, a hydrogen-bonded organic ferroelectric, using real-time time-dependent density functional theory to uncover the microscopic mechanisms of light-induced structural transitions and nonlinear optical responses. High-order harmonic generation in croconic acid is found to be highly sensitive to proton displacement within hydrogen bonds, with polarization switching reshaping internal electronic asymmetry and modulating intersite electron currents. Subangstrom-scale lattice distortions induce marked enhancements or suppressions in the harmonics, highlighting the extreme sensitivity of the nonlinear response to hydrogen-bond configuration. These results reveal a light-driven electron–proton–lattice interaction mechanism in organic ferroelectrics, providing a route toward tunable ultrafast photonic and optoelectronic devices based on molecular materials.
{"title":"Ultrafast laser-induced anharmonic lattice dynamics and nonlinear optical modulation in croconic acid","authors":"Yi-Han Cheng, Hong Zhang, Rui Tang","doi":"10.1063/5.0298932","DOIUrl":"https://doi.org/10.1063/5.0298932","url":null,"abstract":"Ultrafast laser excitation offers a powerful means to modulate material properties on femtosecond timescales. Here, we investigate croconic acid, a hydrogen-bonded organic ferroelectric, using real-time time-dependent density functional theory to uncover the microscopic mechanisms of light-induced structural transitions and nonlinear optical responses. High-order harmonic generation in croconic acid is found to be highly sensitive to proton displacement within hydrogen bonds, with polarization switching reshaping internal electronic asymmetry and modulating intersite electron currents. Subangstrom-scale lattice distortions induce marked enhancements or suppressions in the harmonics, highlighting the extreme sensitivity of the nonlinear response to hydrogen-bond configuration. These results reveal a light-driven electron–proton–lattice interaction mechanism in organic ferroelectrics, providing a route toward tunable ultrafast photonic and optoelectronic devices based on molecular materials.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"158 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759831","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}
Monitoring the dynamic fluctuations of ocean waves using highly sensitive flexible pressure sensors is a highly promising marine observation technology. In this study, we propose a flexible pressure sensor with a gradient microcolumn structure (GCS) fabricated via micro-lithography precision molding technology. The exceptional compressibility of the microcolumn structure significantly enhances the sensor's sensitivity. The GCS sequentially contacts the electrode layer from high to low, effectively modulating the contact area between the sensitive layer and the electrode layer under varying pressures. This design reduces sensitivity attenuation and broadens the detection range. The sensor achieves a wide detection range of 0–600 kPa and an ultrahigh sensitivity of 3848.57 kPa−1. It retains stable performance even after 30 days of underwater immersion and over 3500 cyclic tests. For waterproofing, we encapsulated the sensor with polydimethylsiloxane and attached it to the bottom and sides of a buoy to detect pressure variations induced by waves of different magnitudes in a water tank, enabling real-time wave monitoring. These results demonstrate its great potential for ocean wave monitoring applications.
{"title":"Highly sensitive flexible pressure sensor based on gradient microcolumn structure for ocean wave monitoring","authors":"Xinying Tang, Pan Liao, Lihong Wang, Lixiang Zheng, Yanyue Teng, Jihao Li, Linxu Wang, Kaiyue Niu, Libo Gao, Qi Wen, Junyang Li","doi":"10.1063/5.0298672","DOIUrl":"https://doi.org/10.1063/5.0298672","url":null,"abstract":"Monitoring the dynamic fluctuations of ocean waves using highly sensitive flexible pressure sensors is a highly promising marine observation technology. In this study, we propose a flexible pressure sensor with a gradient microcolumn structure (GCS) fabricated via micro-lithography precision molding technology. The exceptional compressibility of the microcolumn structure significantly enhances the sensor's sensitivity. The GCS sequentially contacts the electrode layer from high to low, effectively modulating the contact area between the sensitive layer and the electrode layer under varying pressures. This design reduces sensitivity attenuation and broadens the detection range. The sensor achieves a wide detection range of 0–600 kPa and an ultrahigh sensitivity of 3848.57 kPa−1. It retains stable performance even after 30 days of underwater immersion and over 3500 cyclic tests. For waterproofing, we encapsulated the sensor with polydimethylsiloxane and attached it to the bottom and sides of a buoy to detect pressure variations induced by waves of different magnitudes in a water tank, enabling real-time wave monitoring. These results demonstrate its great potential for ocean wave monitoring applications.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759832","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}
Jyoti Sharma, Sambit Choudhury, Meng-Jie Huang, Jens Buck, S. Blanco-Canosa, Kai Rossnagel, Sanjoy Kr Mahatha
Charge density waves (CDWs) are a canonical interaction-driven electronic phenomenon with potential technological applications, such as collective electronic switching and local information storage. Here, we investigate the properties of the CDW in the mixed-chalcogen compound 1T-TaSeTe using bulk- and surface-sensitive diffraction and spectroscopy techniques and transport measurements. Compared to the pristine parent compound 1T-TaSe2, we find that the incommensurate CDW appears to remain incommensurate down to low temperatures. The CDW-induced gapping of the Fermi surface is pronounced and may explain the observed semiconductor-like electrical resistivity behavior in combination with chalcogen disorder. Our results demonstrate that disordered chalcogen substitution doping can modify, yet preserve, the characteristic emergent electronic properties of a transition metal dichalcogenide.
{"title":"Persistent incommensurate charge density wave in chalcogen-disordered 1 T -TaSeTe","authors":"Jyoti Sharma, Sambit Choudhury, Meng-Jie Huang, Jens Buck, S. Blanco-Canosa, Kai Rossnagel, Sanjoy Kr Mahatha","doi":"10.1063/5.0303993","DOIUrl":"https://doi.org/10.1063/5.0303993","url":null,"abstract":"Charge density waves (CDWs) are a canonical interaction-driven electronic phenomenon with potential technological applications, such as collective electronic switching and local information storage. Here, we investigate the properties of the CDW in the mixed-chalcogen compound 1T-TaSeTe using bulk- and surface-sensitive diffraction and spectroscopy techniques and transport measurements. Compared to the pristine parent compound 1T-TaSe2, we find that the incommensurate CDW appears to remain incommensurate down to low temperatures. The CDW-induced gapping of the Fermi surface is pronounced and may explain the observed semiconductor-like electrical resistivity behavior in combination with chalcogen disorder. Our results demonstrate that disordered chalcogen substitution doping can modify, yet preserve, the characteristic emergent electronic properties of a transition metal dichalcogenide.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"20 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145760065","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}
Mo Cheng, Xuanyu Jiang, Haoming Zhang, Xiaodong Pi, Deren Yang, Tianqi Deng
Defects are the main performance killer in silicon carbide (SiC) power devices. Among various defect types, dislocations are particularly important, as they affect device reliability. However, first-principles modeling of dislocations is computationally challenging due to their complex, extended structure and topological nature. To overcome this difficulty, we develop a neuroevolution potential (NEP) to enable accurate and large-scale lattice dynamics simulations for defect-containing SiC. To circumvent the difficulty of direct dislocation calculation, the NEP is trained on a first-principles dataset generated by iteratively incorporating various point defects, line defects, and surface structures that are computationally tractable. The resulting NEP reproduces phonon spectra in crystalline and dislocation-containing SiC, indicating its transferability. With this potential, we analyze the phonon characteristics around dislocations in 4H-SiC. Our results reveal localized vibrational modes around dislocation cores, and phonon frequency shifts away from the cores due to dislocation-induced strain fields. This work may facilitate the identification of dislocation phonon signatures and delivers a machine-learning potential that overcomes the computational limitations for large-scale SiC defect simulations.
{"title":"Revealing phonon signature of dislocations in silicon carbide using machine-learning interatomic potential","authors":"Mo Cheng, Xuanyu Jiang, Haoming Zhang, Xiaodong Pi, Deren Yang, Tianqi Deng","doi":"10.1063/5.0298852","DOIUrl":"https://doi.org/10.1063/5.0298852","url":null,"abstract":"Defects are the main performance killer in silicon carbide (SiC) power devices. Among various defect types, dislocations are particularly important, as they affect device reliability. However, first-principles modeling of dislocations is computationally challenging due to their complex, extended structure and topological nature. To overcome this difficulty, we develop a neuroevolution potential (NEP) to enable accurate and large-scale lattice dynamics simulations for defect-containing SiC. To circumvent the difficulty of direct dislocation calculation, the NEP is trained on a first-principles dataset generated by iteratively incorporating various point defects, line defects, and surface structures that are computationally tractable. The resulting NEP reproduces phonon spectra in crystalline and dislocation-containing SiC, indicating its transferability. With this potential, we analyze the phonon characteristics around dislocations in 4H-SiC. Our results reveal localized vibrational modes around dislocation cores, and phonon frequency shifts away from the cores due to dislocation-induced strain fields. This work may facilitate the identification of dislocation phonon signatures and delivers a machine-learning potential that overcomes the computational limitations for large-scale SiC defect simulations.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"4 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759836","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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