Seongmin Im, Wei Hong, Gayatri P Chandran, Xing Wang, Yang Zhao
With increasing interest in utilizing nanostructures as nanoscale heat sources, the ability to precisely measure photothermal effects at the nanoscale has become increasingly significant. Techniques based on fluorescence or Raman signals often suffer from challenges in accurate calibration; far-field imaging methods are limited by diffraction-limited spatial resolution; and electron microscopy requires vacuum conditions, restricting in situ applicability. In contrast, tip-based measurement techniques offer sub-diffraction spatial resolution under ambient conditions, making them well-suited for nanoscale photothermal mapping. In this study, we employ tip-based optical force nanoscopy combined with phase-informed decomposition to investigate the origin of the photothermal force, enable nanoscale mapping, and evaluate temperature sensitivity. Our system achieves a temperature sensitivity of ∼0.1 K without necessitating an additional temperature-sensitive layer. We anticipate that our approach has the potential to serve as a versatile platform for investigating localized thermal effects in fields such as semiconductors, nanophotonics, and photocatalysis.
{"title":"Probing millikelvin temperature sensitivity in chiral nanoparticles via optical forces.","authors":"Seongmin Im, Wei Hong, Gayatri P Chandran, Xing Wang, Yang Zhao","doi":"10.1063/5.0282973","DOIUrl":"10.1063/5.0282973","url":null,"abstract":"<p><p>With increasing interest in utilizing nanostructures as nanoscale heat sources, the ability to precisely measure photothermal effects at the nanoscale has become increasingly significant. Techniques based on fluorescence or Raman signals often suffer from challenges in accurate calibration; far-field imaging methods are limited by diffraction-limited spatial resolution; and electron microscopy requires vacuum conditions, restricting <i>in situ</i> applicability. In contrast, tip-based measurement techniques offer sub-diffraction spatial resolution under ambient conditions, making them well-suited for nanoscale photothermal mapping. In this study, we employ tip-based optical force nanoscopy combined with phase-informed decomposition to investigate the origin of the photothermal force, enable nanoscale mapping, and evaluate temperature sensitivity. Our system achieves a temperature sensitivity of ∼0.1 K without necessitating an additional temperature-sensitive layer. We anticipate that our approach has the potential to serve as a versatile platform for investigating localized thermal effects in fields such as semiconductors, nanophotonics, and photocatalysis.</p>","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"13 10","pages":"101112"},"PeriodicalIF":5.3,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12548564/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145375954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Naomi Pieczulewski, Kathleen T Smith, Corey M Efaw, Arjan Singh, Cameron A Gorsak, Joshua T Buontempo, Jesse Wensel, Kathy Azizie, Katie Gann, Michael O Thompson, Darrell G Schlom, Farhan Rana, Hari P Nair, Steven M Hues, Elton Graugnard, Paul H Davis, Debdeep Jena, Huili Grace Xing, David A Muller
Preserving a contamination-free metal-semiconductor interface in β-Ga2O3 is critical to achieve consistently low resistance ( 1 Ω-mm) ohmic contacts. Here, we report a scanning transmission electron microscopy study on the variation in Ti/Au ohmic contact quality to (010) β-Ga2O3 in a conventional lift-off vs a metal-first process. We observe a thin ∼1 nm carbon barrier between the Ti and Ga2O3 in a non-conductive contact fabricated by a conventional lift-off process, which we attribute to photoresist residue, not previously detected by x-ray photoelectron spectroscopy due to the thinness and patchy coverage of the carbon layer, as well as roughness of the Ga2O3 surface. This thin carbon barrier is confirmed by electron energy loss spectroscopy and atomic force microscopy-infrared spectroscopy. We believe that the presence of the thin and patchy carbon layer leads to the highly inconsistent contact behavior in previous reports on non-alloyed contacts. Adventitious carbon is also observed in a conductive ohmic contact metal-first processing on an as-grown sample. We find that a five minute active oxygen descum is sufficient to remove this carbon on as-grown samples, further improving the ohmic behavior and reducing the contact resistance Rc to 0.06 Ω-mm. We also show that an hour long UV-ozone treatment of the Ga2O3 surface can eliminate carbon residue from the lift-off processing, resulting in a low Rc of 0.05 Ω-mm.
{"title":"Achieving 0.05 Ω-mm contact resistance in non-alloyed Ti/Au ohmics to <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> by removing surface carbon.","authors":"Naomi Pieczulewski, Kathleen T Smith, Corey M Efaw, Arjan Singh, Cameron A Gorsak, Joshua T Buontempo, Jesse Wensel, Kathy Azizie, Katie Gann, Michael O Thompson, Darrell G Schlom, Farhan Rana, Hari P Nair, Steven M Hues, Elton Graugnard, Paul H Davis, Debdeep Jena, Huili Grace Xing, David A Muller","doi":"10.1063/5.0276786","DOIUrl":"10.1063/5.0276786","url":null,"abstract":"<p><p>Preserving a contamination-free metal-semiconductor interface in <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> is critical to achieve consistently low resistance ( <math><mo><</mo></math> 1 Ω-mm) ohmic contacts. Here, we report a scanning transmission electron microscopy study on the variation in Ti/Au ohmic contact quality to (010) <i>β</i>-Ga<sub>2</sub>O<sub>3</sub> in a conventional lift-off vs a metal-first process. We observe a thin ∼1 nm carbon barrier between the Ti and Ga<sub>2</sub>O<sub>3</sub> in a non-conductive contact fabricated by a conventional lift-off process, which we attribute to photoresist residue, not previously detected by x-ray photoelectron spectroscopy due to the thinness and patchy coverage of the carbon layer, as well as roughness of the Ga<sub>2</sub>O<sub>3</sub> surface. This thin carbon barrier is confirmed by electron energy loss spectroscopy and atomic force microscopy-infrared spectroscopy. We believe that the presence of the thin and patchy carbon layer leads to the highly inconsistent contact behavior in previous reports on non-alloyed contacts. Adventitious carbon is also observed in a conductive ohmic contact metal-first processing on an as-grown sample. We find that a five minute active oxygen descum is sufficient to remove this carbon on as-grown samples, further improving the ohmic behavior and reducing the contact resistance R<sub>c</sub> to 0.06 Ω-mm. We also show that an hour long UV-ozone treatment of the Ga<sub>2</sub>O<sub>3</sub> surface can eliminate carbon residue from the lift-off processing, resulting in a low R<sub>c</sub> of 0.05 Ω-mm.</p>","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"13 6","pages":"061122"},"PeriodicalIF":5.3,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12183788/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144482909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Li-Jun Ji, Chen Zhao, Tian-Yi Yang, Hai-Run Yang, Muhammad Azeem, Zi-Ying Li, Rui Feng, Guo-Qiang Feng, Sha Li, Wei Li
Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) have garnered plentiful attention as a result of their exceptional structural flexibility and multiple applications. In this study, we present a 2D HOIP (CHA)2PbBr4 (CHA = cyclohexylamine), for its potential applications in piezoelectricity, such as strain energy sensing and harvesting. Flexible composite films of (CHA)2PbBr4/PDMS (PDMS = polydimethylsiloxane) with a sequence of weight ratios (0, 5, 10, 15, 20 wt %) of (CHA)2PbBr4 were fabricated to analyze the energy harvesting properties. Experimental results demonstrated that a device with 15% composition exhibited the most optimized performance in energy harvesting, producing a peak magnitude of output voltage of 11.6 V, a short-circuit current of 0.38 µA, and a power density of 6.77 µW/cm2, along with notable stability exceeding 4000 cycles. Furthermore, this device exhibited high sensitivity in monitoring many varieties of human movements, such as finger bending and tapping, elbow bending, and gentle foot stamping. The findings of this study indicate that this 2D HOIP holds significant potential for use in flexible sensing and intelligent wearable devices.
{"title":"Energy harvesting and human motion sensing of a 2D piezoelectric hybrid organic–inorganic perovskite","authors":"Li-Jun Ji, Chen Zhao, Tian-Yi Yang, Hai-Run Yang, Muhammad Azeem, Zi-Ying Li, Rui Feng, Guo-Qiang Feng, Sha Li, Wei Li","doi":"10.1063/5.0233435","DOIUrl":"https://doi.org/10.1063/5.0233435","url":null,"abstract":"Two-dimensional (2D) hybrid organic–inorganic perovskites (HOIPs) have garnered plentiful attention as a result of their exceptional structural flexibility and multiple applications. In this study, we present a 2D HOIP (CHA)2PbBr4 (CHA = cyclohexylamine), for its potential applications in piezoelectricity, such as strain energy sensing and harvesting. Flexible composite films of (CHA)2PbBr4/PDMS (PDMS = polydimethylsiloxane) with a sequence of weight ratios (0, 5, 10, 15, 20 wt %) of (CHA)2PbBr4 were fabricated to analyze the energy harvesting properties. Experimental results demonstrated that a device with 15% composition exhibited the most optimized performance in energy harvesting, producing a peak magnitude of output voltage of 11.6 V, a short-circuit current of 0.38 µA, and a power density of 6.77 µW/cm2, along with notable stability exceeding 4000 cycles. Furthermore, this device exhibited high sensitivity in monitoring many varieties of human movements, such as finger bending and tapping, elbow bending, and gentle foot stamping. The findings of this study indicate that this 2D HOIP holds significant potential for use in flexible sensing and intelligent wearable devices.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"18 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The prerequisite of efficient exchange-spring nano-heterostructures, i.e., tuning both hard and soft phases at a nanometer level, has posed significant preparation challenges to ensure effective exchange-coupling. Here, we present a novel approach to fabricate transverse exchange-spring nano-heterostructures using single starting material through an “in situ” electrodeposition technique at room temperature. Utilizing modified acidic bath chemistry and controlled hydrogen evolution, we successfully prepared stress-free, shiny, fine-grained amorphous, and nanocrystalline Co-rich cobalt phosphorus films. These nano-heterostructured films exhibit a unique non-collinear anisotropy-driven transverse exchange-spring behavior, investigated systematically under ambient conditions. The comprehensive functional analyses reveal that intricate interplay between in-plane (IP) anisotropy of amorphous phase and out-of-plane (OOP) anisotropy generating from a nanocrystalline structure compete with each other, while producing characteristic stripe domain structures to novel corrugated stripe domain shapes. The angle-dependent first-order reversal curve distributions demonstrate new insights into the magnetic reversal mechanisms, further confirming the non-exchange-spring and exchange-spring nature of the films depending on the prevalent interfacial exchange coupling. Formation of anisotropy-driven metastable-state due to competition between IP and OOP anisotropy at a particular OOP orientation has led the normal exchange-spring structures to a transverse exchange-spring structure. Micromagnetic simulations, in excellent agreement with experimental data, further elucidate the formation of characteristic stripe domain patterns and the influence of anisotropy on the magnetic properties. The innovative methodology and detailed functional analysis presented here offer significant understanding to the field of exchange-spring magnetic materials, including anisotropy-driven metastable states, demonstrating the potential for scalable and cost-effective fabrication of advanced nano-heterostructures with tailored magnetic properties.
高效交换弹簧纳米异质结构的先决条件是在纳米级水平上调整软硬两相，这为确保有效的交换耦合带来了巨大的制备挑战。在这里，我们提出了一种在室温下通过 "原位 "电沉积技术使用单一起始材料制造横向交换弹簧纳米异质结构的新方法。利用改良的酸性浴化学和受控的氢进化，我们成功制备出了无应力、有光泽、细粒度的非晶和纳米晶富钴磷薄膜。我们在环境条件下对这些纳米异质结构薄膜进行了系统研究，发现它们表现出独特的非共线各向异性驱动的横向交换弹簧行为。综合函数分析表明，非晶相的面内（IP）各向异性与纳米晶结构产生的面外（OOP）各向异性之间存在着错综复杂的相互作用，两者相互竞争，同时产生了从特征条纹畴结构到新型波纹条纹畴形状的变化。与角度相关的一阶反转曲线分布展示了对磁反转机制的新认识，进一步证实了薄膜的非交换弹簧和交换弹簧性质取决于普遍存在的界面交换耦合。在特定的 OOP 方向上，由于 IP 和 OOP 各向异性之间的竞争，形成了各向异性驱动的蜕变态，从而使正常的交换弹簧结构转变为横向交换弹簧结构。微磁模拟与实验数据非常吻合，进一步阐明了特征条纹畴模式的形成以及各向异性对磁性能的影响。本文介绍的创新方法和详细的功能分析为交换弹簧磁性材料领域（包括各向异性驱动的陨变态）提供了重要的认识，展示了以可扩展和具有成本效益的方式制造具有定制磁性能的先进纳米异质结构的潜力。
{"title":"Investigation of transverse exchange-springs in electrodeposited nano-heterostructured films through first-order reversal curve analysis","authors":"Arindam Samanta, Saibal Roy","doi":"10.1063/5.0223485","DOIUrl":"https://doi.org/10.1063/5.0223485","url":null,"abstract":"The prerequisite of efficient exchange-spring nano-heterostructures, i.e., tuning both hard and soft phases at a nanometer level, has posed significant preparation challenges to ensure effective exchange-coupling. Here, we present a novel approach to fabricate transverse exchange-spring nano-heterostructures using single starting material through an “in situ” electrodeposition technique at room temperature. Utilizing modified acidic bath chemistry and controlled hydrogen evolution, we successfully prepared stress-free, shiny, fine-grained amorphous, and nanocrystalline Co-rich cobalt phosphorus films. These nano-heterostructured films exhibit a unique non-collinear anisotropy-driven transverse exchange-spring behavior, investigated systematically under ambient conditions. The comprehensive functional analyses reveal that intricate interplay between in-plane (IP) anisotropy of amorphous phase and out-of-plane (OOP) anisotropy generating from a nanocrystalline structure compete with each other, while producing characteristic stripe domain structures to novel corrugated stripe domain shapes. The angle-dependent first-order reversal curve distributions demonstrate new insights into the magnetic reversal mechanisms, further confirming the non-exchange-spring and exchange-spring nature of the films depending on the prevalent interfacial exchange coupling. Formation of anisotropy-driven metastable-state due to competition between IP and OOP anisotropy at a particular OOP orientation has led the normal exchange-spring structures to a transverse exchange-spring structure. Micromagnetic simulations, in excellent agreement with experimental data, further elucidate the formation of characteristic stripe domain patterns and the influence of anisotropy on the magnetic properties. The innovative methodology and detailed functional analysis presented here offer significant understanding to the field of exchange-spring magnetic materials, including anisotropy-driven metastable states, demonstrating the potential for scalable and cost-effective fabrication of advanced nano-heterostructures with tailored magnetic properties.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"82 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A study on Jahn–Teller distortion reveals that the configuration with Ti-substitution is more stable than that in the case of Ba-replacement. However, magnetoelectric coupling is weak as no spontaneous polarization is formed in the doped unit cell. Taking the atomic radius, low price, and electronegativity into account, Cu was selected to replace Ti together with Cr. Formation energy and phonon spectrum show structural stability. The spontaneous polarization was calculated to be 0.110, 0.114, and 0.247 and 8.078, 0.288, and 0.255 μC/cm2, respectively, in the Cr- and Cu-doped unit cell, corresponding to the directions [100], [010], and [001]. With the application of electric fields, the total magnetic moment was generally enhanced, which resulted in a strong magnetoelectric coupling. In addition, the corresponding coefficient is more than 10 V/cmOe, indicating that the modified BaTiO3 may be a good candidate for single-phase multiferroics. Clearly, co-doping with nonferromagnetic and nonmagnetic elements increases the diversity of new multiferroics.
{"title":"A first-principles study on structural stability and magnetoelectric coupling of two-dimensional BaTiO3 ultrathin film with Cr and Cu substituting Ti site","authors":"Haigen Gao, Bing Wang","doi":"10.1063/5.0223008","DOIUrl":"https://doi.org/10.1063/5.0223008","url":null,"abstract":"A study on Jahn–Teller distortion reveals that the configuration with Ti-substitution is more stable than that in the case of Ba-replacement. However, magnetoelectric coupling is weak as no spontaneous polarization is formed in the doped unit cell. Taking the atomic radius, low price, and electronegativity into account, Cu was selected to replace Ti together with Cr. Formation energy and phonon spectrum show structural stability. The spontaneous polarization was calculated to be 0.110, 0.114, and 0.247 and 8.078, 0.288, and 0.255 μC/cm2, respectively, in the Cr- and Cu-doped unit cell, corresponding to the directions [100], [010], and [001]. With the application of electric fields, the total magnetic moment was generally enhanced, which resulted in a strong magnetoelectric coupling. In addition, the corresponding coefficient is more than 10 V/cmOe, indicating that the modified BaTiO3 may be a good candidate for single-phase multiferroics. Clearly, co-doping with nonferromagnetic and nonmagnetic elements increases the diversity of new multiferroics.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"13 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Solid phase epitaxy (SPE) has been widely employed for various thin-film materials, making it valuable for industrial applications due to its scalability. In complex oxides, SPE has been limited to a few materials because of the challenges in maintaining stoichiometric control during growth, particularly when volatile phases are present at high temperatures. Here, we investigate the impact of encapsulation layers on the SPE of complex oxides, using SrRuO3 (SRO) as a model system. An amorphous SRO layer was deposited on a SrTiO3 (STO) substrate, followed by the transfer of a single-crystalline STO membrane as an encapsulation layer in order to suppress the evaporation of volatile species (RuO2) during the SPE process. Whereas both encapsulated and unencapsulated SRO layers were successfully crystallized, the unencapsulated films suffered a substantial loss of Ru ions—exceeding 20%—compared to their encapsulated counterparts. This loss of Ru ions led to a loss of metallicity in the unencapsulated SRO layers, whereas the encapsulated layers retained their metallic ferromagnetic properties. This study demonstrates that the encapsulation provided by oxide membranes effectively suppresses stoichiometric loss during SPE, presenting a new strategy in stabilizing a broader class of functional oxides as epitaxial thin films.
{"title":"Solid phase epitaxy of SrRuO3 encapsulated by SrTiO3 membranes","authors":"Jieyang Zhou, Mingzhen Feng, Hudson Shih, Yayoi Takamura, Seung Sae Hong","doi":"10.1063/5.0219028","DOIUrl":"https://doi.org/10.1063/5.0219028","url":null,"abstract":"Solid phase epitaxy (SPE) has been widely employed for various thin-film materials, making it valuable for industrial applications due to its scalability. In complex oxides, SPE has been limited to a few materials because of the challenges in maintaining stoichiometric control during growth, particularly when volatile phases are present at high temperatures. Here, we investigate the impact of encapsulation layers on the SPE of complex oxides, using SrRuO3 (SRO) as a model system. An amorphous SRO layer was deposited on a SrTiO3 (STO) substrate, followed by the transfer of a single-crystalline STO membrane as an encapsulation layer in order to suppress the evaporation of volatile species (RuO2) during the SPE process. Whereas both encapsulated and unencapsulated SRO layers were successfully crystallized, the unencapsulated films suffered a substantial loss of Ru ions—exceeding 20%—compared to their encapsulated counterparts. This loss of Ru ions led to a loss of metallicity in the unencapsulated SRO layers, whereas the encapsulated layers retained their metallic ferromagnetic properties. This study demonstrates that the encapsulation provided by oxide membranes effectively suppresses stoichiometric loss during SPE, presenting a new strategy in stabilizing a broader class of functional oxides as epitaxial thin films.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"38 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dong Gao, Ting Yang, Fu Tang, Jiejun Su, Weihao Yang, Dengfu Deng, Yunfei Xie, Jun Qin, Xiao Liang, Lei Bi
Antiferromagnetic Weyl semimetal Mn3Sn exhibiting strong magneto-optical Kerr effect (MOKE) due to non-zero Berry curvature is attractive for spintronic and photonic device applications. Despite many reports on the anisotropic anomalous Hall effect (AHE), so far, there have been few studies on its anisotropic optical properties. In this work, we experimentally characterized the anisotropic optical and magneto-optical (MO) properties of Mn3Sn(20)/MgO(110) and Mn3Sn(0001)/Al2O3(0001) epitaxial films using ellipsometry in the wavelength range from 300 to 1690 nm. By measuring the Mueller matrix of magnetized Mn3Sn, the anisotropic permittivity tensor is determined using the 4 × 4 transfer matrix method. Temperature dependent MOKE measurement confirmed the origin of the anisotropic MO effect to the non-zero Berry curvature of the chiral magnetic phase. The measured permittivity also agrees well with first-principles calculations. The anisotropic optical and MO properties determined in this work can be useful for Mn3Sn based spintronic device characterization and photonic device development.
{"title":"Anisotropic optical and magneto-optical properties of antiferromagnetic Weyl semimetal Mn3Sn epitaxial thin films","authors":"Dong Gao, Ting Yang, Fu Tang, Jiejun Su, Weihao Yang, Dengfu Deng, Yunfei Xie, Jun Qin, Xiao Liang, Lei Bi","doi":"10.1063/5.0225441","DOIUrl":"https://doi.org/10.1063/5.0225441","url":null,"abstract":"Antiferromagnetic Weyl semimetal Mn3Sn exhibiting strong magneto-optical Kerr effect (MOKE) due to non-zero Berry curvature is attractive for spintronic and photonic device applications. Despite many reports on the anisotropic anomalous Hall effect (AHE), so far, there have been few studies on its anisotropic optical properties. In this work, we experimentally characterized the anisotropic optical and magneto-optical (MO) properties of Mn3Sn(20)/MgO(110) and Mn3Sn(0001)/Al2O3(0001) epitaxial films using ellipsometry in the wavelength range from 300 to 1690 nm. By measuring the Mueller matrix of magnetized Mn3Sn, the anisotropic permittivity tensor is determined using the 4 × 4 transfer matrix method. Temperature dependent MOKE measurement confirmed the origin of the anisotropic MO effect to the non-zero Berry curvature of the chiral magnetic phase. The measured permittivity also agrees well with first-principles calculations. The anisotropic optical and MO properties determined in this work can be useful for Mn3Sn based spintronic device characterization and photonic device development.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"5 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Kontaxi, G. Wensink, P. M. Sberna, M. Rücker, V. Garbin, M. J. Serpe, H. Bazyar
We introduce Microgel-based Etalon Membranes (MEMs), based on the combination of stimuli-responsive microgels with an etalon, which is an optical device consisting of two reflecting plates and is used to filter specific wavelengths of light. The microgels are sandwiched between two reflective layers and, in response to a stimulus (e.g., temperature, pH, or biomarker concentration), swell or de-swell, thereby changing the distance between the two reflective layers and generating multiple peaks in the reflectance spectra. This property gives a MEM the unique capability of simultaneous separation and tunable responses to environmental changes and/or biomarker concentrations. We propose a design based on gold layers on a silicon nitride wafer membrane. Our comprehensive characterization, employing permeability experiments, in situ optical reflectance spectroscopy, in-liquid atomic force microscopy (AFM) analysis, and captive bubble contact angle measurements, elucidates the dynamic response of MEM to pH, temperature, and glucose stimuli and the corresponding effect of microgel swelling/de-swelling on the membrane properties, e.g., permeability. The AFM results confirm the dynamic changes of the microgel layer’s thickness on the membrane surface in response to the stimuli. Although the microgel’s swelling/de-swelling influences the effective pore radius, the decrease in the membrane’s permeance is limited to less than 10%. In the swollen state of the microgels, the etalon membranes show a prominent hydrophilic behavior, while they become less hydrophilic in the microgels’ de-swollen state. This work introduces MEM and provides novel insights into their behavior. The fundamental understanding that we reveal opens the way to applications ranging from point-of-care testing to continuous environmental monitoring.
我们介绍了基于微凝胶的埃特隆膜（MEM），其基础是刺激响应型微凝胶与埃特隆的结合，埃特隆是一种由两个反射板组成的光学设备，用于过滤特定波长的光。微凝胶夹在两个反射层之间，在受到刺激（如温度、pH 值或生物标记物浓度）时，会膨胀或脱泡，从而改变两个反射层之间的距离，在反射光谱中产生多个峰值。这种特性使 MEM 具备了同时分离和对环境变化和/或生物标记物浓度做出可调响应的独特能力。我们提出了一种基于氮化硅晶片膜上金层的设计。我们采用渗透性实验、原位光学反射光谱、液态原子力显微镜（AFM）分析和俘获气泡接触角测量等综合表征方法，阐明了 MEM 对 pH 值、温度和葡萄糖刺激的动态响应，以及微凝胶膨胀/脱膨胀对膜特性（如渗透性）的相应影响。原子力显微镜的结果证实了膜表面微凝胶层的厚度在刺激下的动态变化。虽然微凝胶的溶胀/脱溶胀会影响有效孔半径，但膜渗透率的降低幅度却小于 10%。在微凝胶的膨胀状态下，乙撑膜表现出突出的亲水性，而在微凝胶的消肿状态下，它们的亲水性则变弱。这项研究介绍了 MEM，并对其行为提出了新的见解。我们所揭示的基本认识为从护理点测试到连续环境监测等各种应用开辟了道路。
{"title":"Microgel-based etalon membranes: Characterization and properties","authors":"G. Kontaxi, G. Wensink, P. M. Sberna, M. Rücker, V. Garbin, M. J. Serpe, H. Bazyar","doi":"10.1063/5.0227483","DOIUrl":"https://doi.org/10.1063/5.0227483","url":null,"abstract":"We introduce Microgel-based Etalon Membranes (MEMs), based on the combination of stimuli-responsive microgels with an etalon, which is an optical device consisting of two reflecting plates and is used to filter specific wavelengths of light. The microgels are sandwiched between two reflective layers and, in response to a stimulus (e.g., temperature, pH, or biomarker concentration), swell or de-swell, thereby changing the distance between the two reflective layers and generating multiple peaks in the reflectance spectra. This property gives a MEM the unique capability of simultaneous separation and tunable responses to environmental changes and/or biomarker concentrations. We propose a design based on gold layers on a silicon nitride wafer membrane. Our comprehensive characterization, employing permeability experiments, in situ optical reflectance spectroscopy, in-liquid atomic force microscopy (AFM) analysis, and captive bubble contact angle measurements, elucidates the dynamic response of MEM to pH, temperature, and glucose stimuli and the corresponding effect of microgel swelling/de-swelling on the membrane properties, e.g., permeability. The AFM results confirm the dynamic changes of the microgel layer’s thickness on the membrane surface in response to the stimuli. Although the microgel’s swelling/de-swelling influences the effective pore radius, the decrease in the membrane’s permeance is limited to less than 10%. In the swollen state of the microgels, the etalon membranes show a prominent hydrophilic behavior, while they become less hydrophilic in the microgels’ de-swollen state. This work introduces MEM and provides novel insights into their behavior. The fundamental understanding that we reveal opens the way to applications ranging from point-of-care testing to continuous environmental monitoring.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"1 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pengcheng Zhu, Li Ye, Xiaolei Li, Tianxing Wang, Yao Zhong, Lin Zhuang
Hydrogen evolution reactions (HERs) and oxygen evolution reactions (OERs) are crucial for renewable energy production. Developing stable, cost-effective, and highly catalytic HER and OER electrocatalysts is paramount. In this study, a combination of hydrothermal synthesis and annealing was used to fabricate nickel sulfide (Ni3S2) particle–embedded nanotubes supported on nickel (Ni) foam (Ni3S2 PN/NF). The Ni3S2 PN/NF structures featured a highly branched morphology with a large specific surface area, surpassing that of conventional Ni metal nanotubes. This design increased the number of reactive sites and enhanced the charge-transfer process. The Ni foam substrate expanded the contact area of Ni3S2, thereby improving conductivity and facilitating the adsorption/desorption of intermediates on the Ni3S2 surface. Density functional theory calculations showed that the electronic structure of Ni3S2 provides excellent conductivity. Moreover, the multi-branched structure and inherent conductivity of the NiS nanomaterials enhanced the Ni3S2 PN/NF performance in 1M KOH, with overpotentials of 87 and 210 mV with iR compensation at 10 mA cm−2 for the HER and OER, respectively. The synthesized Ni3S2 PN/NF also exhibited robust durability for 20 h. These results demonstrate that Ni3S2 PN/NF is an excellent catalyst for both HER and OER.
氢进化反应（HER）和氧进化反应（OER）对于可再生能源的生产至关重要。开发稳定、经济、高催化性的 HER 和 OER 电催化剂至关重要。本研究采用水热合成和退火相结合的方法，制备了硫化镍（Ni3S2）颗粒嵌入式纳米管（Ni3S2 PN/NF），并将其支撑在镍（Ni）泡沫上。Ni3S2 PN/NF 结构具有高度支化的形态，比表面积大，超过了传统的镍金属纳米管。这种设计增加了反应位点的数量，增强了电荷转移过程。泡沫镍基底扩大了 Ni3S2 的接触面积，从而提高了导电性，并促进了中间产物在 Ni3S2 表面的吸附/解吸。密度泛函理论计算表明，Ni3S2 的电子结构具有出色的导电性。此外，NiS 纳米材料的多分支结构和固有导电性增强了 Ni3S2 PN/NF 在 1M KOH 中的性能，在 10 mA cm-2 的 iR 补偿条件下，HER 和 OER 的过电位分别为 87 mV 和 210 mV。这些结果表明，Ni3S2 PN/NF 是一种出色的 HER 和 OER 催化剂。
{"title":"Ni3S2 particle–embedded nanotubes as a high-performance electrocatalyst for overall water splitting","authors":"Pengcheng Zhu, Li Ye, Xiaolei Li, Tianxing Wang, Yao Zhong, Lin Zhuang","doi":"10.1063/5.0225168","DOIUrl":"https://doi.org/10.1063/5.0225168","url":null,"abstract":"Hydrogen evolution reactions (HERs) and oxygen evolution reactions (OERs) are crucial for renewable energy production. Developing stable, cost-effective, and highly catalytic HER and OER electrocatalysts is paramount. In this study, a combination of hydrothermal synthesis and annealing was used to fabricate nickel sulfide (Ni3S2) particle–embedded nanotubes supported on nickel (Ni) foam (Ni3S2 PN/NF). The Ni3S2 PN/NF structures featured a highly branched morphology with a large specific surface area, surpassing that of conventional Ni metal nanotubes. This design increased the number of reactive sites and enhanced the charge-transfer process. The Ni foam substrate expanded the contact area of Ni3S2, thereby improving conductivity and facilitating the adsorption/desorption of intermediates on the Ni3S2 surface. Density functional theory calculations showed that the electronic structure of Ni3S2 provides excellent conductivity. Moreover, the multi-branched structure and inherent conductivity of the NiS nanomaterials enhanced the Ni3S2 PN/NF performance in 1M KOH, with overpotentials of 87 and 210 mV with iR compensation at 10 mA cm−2 for the HER and OER, respectively. The synthesized Ni3S2 PN/NF also exhibited robust durability for 20 h. These results demonstrate that Ni3S2 PN/NF is an excellent catalyst for both HER and OER.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"27 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142197806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hemant Ghadi, Evan Cornuellue, Joe F. Mcglone, Alexander Senckowski, Shivam Sharma, Man Hoi Wong, Uttam Singisetti, Steven A. Ringel
This study provides a comprehensive analysis of the dominant deep acceptor level in nitrogen-doped beta-phase gallium oxide (β-Ga2O3), elucidating and reconciling the hole emission features observed in deep-level optical spectroscopy (DLOS). The unique behavior of this defect, coupled with its small optical cross section, complicates trap concentration analysis using DLOS, which is essential for defect characterization in β-Ga2O3. A complex feature arises in DLOS results due to simultaneous electron emission to the conduction band and hole emission to the valence band from the same defect state, indicating the formation of two distinct atomic configurations and suggesting metastable defect characteristics. This study discusses the implications of this behavior on DLOS analysis and employs advanced spectroscopy techniques such as double-beam DLOS and optical isothermal measurements to address these complications. The double-beam DLOS method reveals a distinct hole emission process at EV+1.3 eV previously obscured in conventional DLOS. Optical isothermal measurements further characterize this energy level, appearing only in N-doped β-Ga2O3. This enables an estimate of the β-Ga2O3 hole effective mass by analyzing temperature-dependent carrier emission rates. This work highlights the impact of partial trap-filling behavior on DLOS analysis and identifies the presence of hole trapping and emission in β-Ga2O3. Although N-doping is ideal for creating semi-insulating material through the efficient compensation of free electrons, this study also reveals a significant hole emission and migration process within the weak electric fields of the Schottky diode depletion region.
{"title":"Comprehensive characterization of nitrogen-related defect states in β-Ga2O3 using quantitative optical and thermal defect spectroscopy methods","authors":"Hemant Ghadi, Evan Cornuellue, Joe F. Mcglone, Alexander Senckowski, Shivam Sharma, Man Hoi Wong, Uttam Singisetti, Steven A. Ringel","doi":"10.1063/5.0225570","DOIUrl":"https://doi.org/10.1063/5.0225570","url":null,"abstract":"This study provides a comprehensive analysis of the dominant deep acceptor level in nitrogen-doped beta-phase gallium oxide (β-Ga2O3), elucidating and reconciling the hole emission features observed in deep-level optical spectroscopy (DLOS). The unique behavior of this defect, coupled with its small optical cross section, complicates trap concentration analysis using DLOS, which is essential for defect characterization in β-Ga2O3. A complex feature arises in DLOS results due to simultaneous electron emission to the conduction band and hole emission to the valence band from the same defect state, indicating the formation of two distinct atomic configurations and suggesting metastable defect characteristics. This study discusses the implications of this behavior on DLOS analysis and employs advanced spectroscopy techniques such as double-beam DLOS and optical isothermal measurements to address these complications. The double-beam DLOS method reveals a distinct hole emission process at EV+1.3 eV previously obscured in conventional DLOS. Optical isothermal measurements further characterize this energy level, appearing only in N-doped β-Ga2O3. This enables an estimate of the β-Ga2O3 hole effective mass by analyzing temperature-dependent carrier emission rates. This work highlights the impact of partial trap-filling behavior on DLOS analysis and identifies the presence of hole trapping and emission in β-Ga2O3. Although N-doping is ideal for creating semi-insulating material through the efficient compensation of free electrons, this study also reveals a significant hole emission and migration process within the weak electric fields of the Schottky diode depletion region.","PeriodicalId":7985,"journal":{"name":"APL Materials","volume":"210 1","pages":""},"PeriodicalIF":6.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142197796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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