Pub Date : 2023-04-04DOI: 10.1088/2515-7639/acd27a
C. Witteveen, E. Nocerino, Sara A. López-Paz, H. Jeschke, V. Pomjakushin, M. Månsson, F. V. von Rohr
We report on the synthesis of LiCrTe 2 single crystals and on their anisotropic magnetic properties. We have obtained these single crystals by employing a Te/Li-flux synthesis method. We find LiCrTe 2 to crystallize in a TlCdS 2 -type structure with cell parameters of a = 3.9512(5) Å and c = 6.6196(7) Å at T = 175 K. The content of lithium in these crystals was determined to be neary stoichiometric by means of neutron diffraction. We find a pronounced magnetic transition at TNab = 144 K and TNc = 148 K, respectively. These transition temperatures are substantially higher than earlier reports on polycrystalline samples. We have performed neutron powder diffraction measurements that reveal that the long-range low-temperature magnetic structure of single crystalline LiCrTe 2 is an A-type antiferromagnetic structure. Our DFT calculations are in good agreement with these experimental observations. We find the system to be easy axis with moments oriented along the c-direction experimentally as well as in our calculations. Thereby, the magnetic Hamiltonian can be written as H=HHeisenberg+∑iKc(Siz)2 with Kc=−0.34 K (where |Sz|=32 ). We find LiCrTe 2 to be highly anisotropic, with a pronounced metamagnetic transition for H⊥ab with a critical field of μHMM (5 K) ≈ 2.5 T. Using detailed orientation-dependent magnetization measurements, we have determined the magnetic phase diagram of this material. Our findings suggest that LiCrTe 2 is a promising material for exploring the interplay between crystal structure and magnetism, and could have potential applications in spin-based 2D devices.
{"title":"Synthesis and anisotropic magnetic properties of LiCrTe 2 single crystals with a triangular-lattice antiferromagnetic structure","authors":"C. Witteveen, E. Nocerino, Sara A. López-Paz, H. Jeschke, V. Pomjakushin, M. Månsson, F. V. von Rohr","doi":"10.1088/2515-7639/acd27a","DOIUrl":"https://doi.org/10.1088/2515-7639/acd27a","url":null,"abstract":"We report on the synthesis of LiCrTe 2 single crystals and on their anisotropic magnetic properties. We have obtained these single crystals by employing a Te/Li-flux synthesis method. We find LiCrTe 2 to crystallize in a TlCdS 2 -type structure with cell parameters of a = 3.9512(5) Å and c = 6.6196(7) Å at T = 175 K. The content of lithium in these crystals was determined to be neary stoichiometric by means of neutron diffraction. We find a pronounced magnetic transition at TNab = 144 K and TNc = 148 K, respectively. These transition temperatures are substantially higher than earlier reports on polycrystalline samples. We have performed neutron powder diffraction measurements that reveal that the long-range low-temperature magnetic structure of single crystalline LiCrTe 2 is an A-type antiferromagnetic structure. Our DFT calculations are in good agreement with these experimental observations. We find the system to be easy axis with moments oriented along the c-direction experimentally as well as in our calculations. Thereby, the magnetic Hamiltonian can be written as H=HHeisenberg+∑iKc(Siz)2 with Kc=−0.34 K (where |Sz|=32 ). We find LiCrTe 2 to be highly anisotropic, with a pronounced metamagnetic transition for H⊥ab with a critical field of μHMM (5 K) ≈ 2.5 T. Using detailed orientation-dependent magnetization measurements, we have determined the magnetic phase diagram of this material. Our findings suggest that LiCrTe 2 is a promising material for exploring the interplay between crystal structure and magnetism, and could have potential applications in spin-based 2D devices.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90385461","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 : 2023-04-01DOI: 10.1088/2515-7639/accc56
Kenna L. Salvatore, Christopher R. Tang, Edelmy Marin Bernardez, Weiqiao Wesley, Justin Fang, Katherine Lee, Ariadna Paltis, Chloe Nevers, S. Mcguire, Nathaniel Hurley, Xiao Tong, E. Takeuchi, K. Takeuchi, A. Marschilok, Stanislaus S. Wong
The syntheses of FeS2 and Fe3S4 nanomaterials were optimized using a novel facile, surfactant-free, and microwave-assisted, one-pot synthesis method, run under ambient and reasonably mild reaction conditions. Synthetic parameters, such as metal precursor salt identity, reaction time, reaction temperature, metal:sulfur molar ratios, and solvent combinations, were all systematically investigated and optimized. A series of FeS2 (pyrite) samples was initially fabricated using thioacetamide (TAA) as the sulfur precursor to generate a distinctive, uniform octahedra-based morphology. Switching the sulfur precursor from TAA to L-cysteine resulted in a corresponding transformation in not only chemical composition from FeS2 to an iron thiospinel structure, Fe3S4 (otherwise known as greigite), but also an associated morphological evolution from octahedra to nanosheet aggregates. The study of these materials has enabled crucial insights into the formation mechanisms of these materials under a relatively non-conventional microwave-assisted setting. Furthermore, in separate experiments, multi-walled carbon nanotubes (MWNTs) and graphene were added in with underlying metal sulfide species to create conductive Fe–S/MWNT composites and Fe–S/graphene composites, respectively. The method of addition of either MWNTs or graphene was also explored, wherein an ‘ex-situ’ synthetic procedure was found to be the least disruptive means of attachment and immobilization onto iron sulfide co-reagents as a means of preserving the latter’s inherent composition and morphology. The redox acidity for the parent material and associated composites demonstrates the utility of our as-developed synthetic methods for creating motifs relevant for electrochemical applications, such as energy storage.
{"title":"Microwave-assisted synthesis of iron sulfide motifs for electrochemical applications","authors":"Kenna L. Salvatore, Christopher R. Tang, Edelmy Marin Bernardez, Weiqiao Wesley, Justin Fang, Katherine Lee, Ariadna Paltis, Chloe Nevers, S. Mcguire, Nathaniel Hurley, Xiao Tong, E. Takeuchi, K. Takeuchi, A. Marschilok, Stanislaus S. Wong","doi":"10.1088/2515-7639/accc56","DOIUrl":"https://doi.org/10.1088/2515-7639/accc56","url":null,"abstract":"The syntheses of FeS2 and Fe3S4 nanomaterials were optimized using a novel facile, surfactant-free, and microwave-assisted, one-pot synthesis method, run under ambient and reasonably mild reaction conditions. Synthetic parameters, such as metal precursor salt identity, reaction time, reaction temperature, metal:sulfur molar ratios, and solvent combinations, were all systematically investigated and optimized. A series of FeS2 (pyrite) samples was initially fabricated using thioacetamide (TAA) as the sulfur precursor to generate a distinctive, uniform octahedra-based morphology. Switching the sulfur precursor from TAA to L-cysteine resulted in a corresponding transformation in not only chemical composition from FeS2 to an iron thiospinel structure, Fe3S4 (otherwise known as greigite), but also an associated morphological evolution from octahedra to nanosheet aggregates. The study of these materials has enabled crucial insights into the formation mechanisms of these materials under a relatively non-conventional microwave-assisted setting. Furthermore, in separate experiments, multi-walled carbon nanotubes (MWNTs) and graphene were added in with underlying metal sulfide species to create conductive Fe–S/MWNT composites and Fe–S/graphene composites, respectively. The method of addition of either MWNTs or graphene was also explored, wherein an ‘ex-situ’ synthetic procedure was found to be the least disruptive means of attachment and immobilization onto iron sulfide co-reagents as a means of preserving the latter’s inherent composition and morphology. The redox acidity for the parent material and associated composites demonstrates the utility of our as-developed synthetic methods for creating motifs relevant for electrochemical applications, such as energy storage.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84450407","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 : 2023-03-29DOI: 10.1088/2515-7639/acc893
S. Feng, Yuanhang Cheng, H. Yip, Yufei Zhong, P. W. Fong, Gang Li, A. Ng, Cong Chen, L. A. Castriotta, F. Matteocci, L. Vesce, D. Saranin, A. Di Carlo, Puqun Wang, J. Ho, Yi Hou, F. Lin, A. Aberle, Zhaoning Song, Yanfa Yan, Xu Chen, Y. Yang, Ali Ashgar Syed, I. Ahmad, T. Leung, Yantao Wang, Yuanjing Lin, A. Ng, Yin Li, Firouzeh G. Ebadi, W. Tress, G. Richardson, Chuang-Ye Ge, Hanlin Hu, M. Karimipour, Fanny Baumann, Kenedy Tabah Tanko, C. Pereyra, Sonia R. Raga, Haibing Xie, M. Lira-Cantú, M. Khenkin, I. Visoly-Fisher, E. Katz, Y. Vaynzof, Rosario Vidal, Guicheng Yu, Hao‐Wu Lin, Shuchen Weng, Shifeng Wang, A. Djurišić
Perovskite solar cells (PSCs) represent one of the most promising emerging photovoltaic technologies due to their high power conversion efficiency. However, despite the huge progress made not only in terms of the efficiency achieved, but also fundamental understanding of the relevant physics of the devices and issues which affect their efficiency and stability, there are still unresolved problems and obstacles on the path toward commercialization of this promising technology. In this roadmap, we aim to provide a concise and up to date summary of outstanding issues and challenges, and the progress made toward addressing these issues. While the format of this article is not meant to be a comprehensive review of the topic, it provides a collection of the viewpoints of the experts in the field, which covers a broad range of topics related to PSC commercialization, including those relevant for manufacturing (scaling up, different types of devices), operation and stability (various factors), and environmental issues (in particular the use of lead). We hope that the article will provide a useful resource for researchers in the field and that it will facilitate discussions and move forward toward addressing the outstanding challenges in this fast-developing field.
{"title":"Roadmap on commercialization of metal halide perovskite photovoltaics","authors":"S. Feng, Yuanhang Cheng, H. Yip, Yufei Zhong, P. W. Fong, Gang Li, A. Ng, Cong Chen, L. A. Castriotta, F. Matteocci, L. Vesce, D. Saranin, A. Di Carlo, Puqun Wang, J. Ho, Yi Hou, F. Lin, A. Aberle, Zhaoning Song, Yanfa Yan, Xu Chen, Y. Yang, Ali Ashgar Syed, I. Ahmad, T. Leung, Yantao Wang, Yuanjing Lin, A. Ng, Yin Li, Firouzeh G. Ebadi, W. Tress, G. Richardson, Chuang-Ye Ge, Hanlin Hu, M. Karimipour, Fanny Baumann, Kenedy Tabah Tanko, C. Pereyra, Sonia R. Raga, Haibing Xie, M. Lira-Cantú, M. Khenkin, I. Visoly-Fisher, E. Katz, Y. Vaynzof, Rosario Vidal, Guicheng Yu, Hao‐Wu Lin, Shuchen Weng, Shifeng Wang, A. Djurišić","doi":"10.1088/2515-7639/acc893","DOIUrl":"https://doi.org/10.1088/2515-7639/acc893","url":null,"abstract":"Perovskite solar cells (PSCs) represent one of the most promising emerging photovoltaic technologies due to their high power conversion efficiency. However, despite the huge progress made not only in terms of the efficiency achieved, but also fundamental understanding of the relevant physics of the devices and issues which affect their efficiency and stability, there are still unresolved problems and obstacles on the path toward commercialization of this promising technology. In this roadmap, we aim to provide a concise and up to date summary of outstanding issues and challenges, and the progress made toward addressing these issues. While the format of this article is not meant to be a comprehensive review of the topic, it provides a collection of the viewpoints of the experts in the field, which covers a broad range of topics related to PSC commercialization, including those relevant for manufacturing (scaling up, different types of devices), operation and stability (various factors), and environmental issues (in particular the use of lead). We hope that the article will provide a useful resource for researchers in the field and that it will facilitate discussions and move forward toward addressing the outstanding challenges in this fast-developing field.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87778418","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 : 2023-03-03DOI: 10.1088/2515-7639/acbdef
M. M. Amaral, S. B. Mujib, H. Zanin, Gurpreet Singh
Energy storage devices beyond lithium-ion batteries (LIBs), such as sodium-ion, potassium-ion, lithium-sulfur batteries, and supercapacitors are being considered as alternative systems to meet the fast-growing demand for grid-scale storage and large electric vehicles. This perspective highlights the opportunities that Si-based polymer-derived ceramics (PDCs) present for energy storage devices beyond LIBs, the complexities that exist in determining the structure-performance relationships, and the need for in situ and operando characterizations, which can be employed to overcome the complexities, allowing successful integration of PDC-based electrodes in systems beyond LIBs.
{"title":"A perspective on silicon-based polymer-derived ceramics materials for beyond lithium-ion batteries","authors":"M. M. Amaral, S. B. Mujib, H. Zanin, Gurpreet Singh","doi":"10.1088/2515-7639/acbdef","DOIUrl":"https://doi.org/10.1088/2515-7639/acbdef","url":null,"abstract":"Energy storage devices beyond lithium-ion batteries (LIBs), such as sodium-ion, potassium-ion, lithium-sulfur batteries, and supercapacitors are being considered as alternative systems to meet the fast-growing demand for grid-scale storage and large electric vehicles. This perspective highlights the opportunities that Si-based polymer-derived ceramics (PDCs) present for energy storage devices beyond LIBs, the complexities that exist in determining the structure-performance relationships, and the need for in situ and operando characterizations, which can be employed to overcome the complexities, allowing successful integration of PDC-based electrodes in systems beyond LIBs.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76348964","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 : 2023-03-03DOI: 10.1088/2515-7639/acc13b
M. J. Pereira, Tiago A. C. Santos, R. Correia, J. Amaral, V. Amaral, S. Fabbrici, F. Albertini
An innovative study of the magnetocaloric effect (MCE) was performed by mapping the effect based on direct measurements of the temperature change during magnetic field cycles with microscopic resolution (85 μm) on a Co-doped Ni–Mn–Ga bulk sample using infrared thermography on the whole sample. The MCE maps were constructed for different sample temperatures (T sample), cycling both on heating (from 272.8 K up to T sample, with T sample ⩽ 327.0 K) and on cooling (from 340.0 K down to T sample, with T sample ⩾ 266.8 K), cycling a 1.2 T magnetic field at each T sample value. The MCE maps were calculated to evaluate the amplitude of the effect at the microscale for all T sample values. This allows to analyze the contribution of each micrometric portion of the sample to the spatially heterogeneous behavior that was found. Significant differences of the MCE on heating and cooling are present associated to inhomogeneity dynamics, mostly near the structural transformation. The amplitude of the MCE and its inhomogeneity are both much more pronounced on the heating process. On the cooling process the effect behaves quite homogeneously since the structural transformation already occurred during the cooling to reach T sample. The behavior of the MCE at selected map coordinates was scrutinized, revealing significant differences amongst sample locations. Moreover, the extreme amplitudes of MCE registered for diverse micro-regions occur at different temperatures, suggesting that the structural transformation occurs at varying temperatures and with different magnitudes. The study innovates by constructing MCE maps to evaluate minority behaviors in the MCE in contrast with the average behavior of the effect. This study displays the capability to discriminate the behavior of the transformation at the microscale.
{"title":"Mapping the magnetocaloric effect at the microscale on a ferromagnetic shape memory alloy with infrared thermography","authors":"M. J. Pereira, Tiago A. C. Santos, R. Correia, J. Amaral, V. Amaral, S. Fabbrici, F. Albertini","doi":"10.1088/2515-7639/acc13b","DOIUrl":"https://doi.org/10.1088/2515-7639/acc13b","url":null,"abstract":"An innovative study of the magnetocaloric effect (MCE) was performed by mapping the effect based on direct measurements of the temperature change during magnetic field cycles with microscopic resolution (85 μm) on a Co-doped Ni–Mn–Ga bulk sample using infrared thermography on the whole sample. The MCE maps were constructed for different sample temperatures (T sample), cycling both on heating (from 272.8 K up to T sample, with T sample ⩽ 327.0 K) and on cooling (from 340.0 K down to T sample, with T sample ⩾ 266.8 K), cycling a 1.2 T magnetic field at each T sample value. The MCE maps were calculated to evaluate the amplitude of the effect at the microscale for all T sample values. This allows to analyze the contribution of each micrometric portion of the sample to the spatially heterogeneous behavior that was found. Significant differences of the MCE on heating and cooling are present associated to inhomogeneity dynamics, mostly near the structural transformation. The amplitude of the MCE and its inhomogeneity are both much more pronounced on the heating process. On the cooling process the effect behaves quite homogeneously since the structural transformation already occurred during the cooling to reach T sample. The behavior of the MCE at selected map coordinates was scrutinized, revealing significant differences amongst sample locations. Moreover, the extreme amplitudes of MCE registered for diverse micro-regions occur at different temperatures, suggesting that the structural transformation occurs at varying temperatures and with different magnitudes. The study innovates by constructing MCE maps to evaluate minority behaviors in the MCE in contrast with the average behavior of the effect. This study displays the capability to discriminate the behavior of the transformation at the microscale.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75812255","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 : 2023-03-02DOI: 10.1088/2515-7639/acb7a1
U. Kraft, M. Nikolka, Ging-Ji Nathan Wang, Yeongin Kim, R. Pfattner, Maryam Alsufyani, Iain McCulloch, B. Murmann, Z. Bao
A set of unique features, including large-area solution processing on flexible and stretchable substrates, make polymer semiconductors a promising material choice for a range of state-of-the-art applications in electronics, optoelectronics and sensing. Yet, an inherent weakness of polymer semiconductors remains their low dielectric constants, increasing their susceptibility toward unscreened dipoles. These dipoles are particularly prevalent at polymer-dielectric interfaces with high-k dielectrics, which are essential for the operation of devices such as low-voltage field-effect transistors. This shortcoming can be addressed by using self-assembled monolayers (SAMs) to passivate surfaces that impact charge transport. However, SAM-treatment also increases the hydrophobicity of surfaces and therefore poses a challenge for subsequent solution processing steps and complex packaging of devices. Here, we report low-voltage polymer transistors processed by spin coating of the polymer semiconductors on highly hydrophobic SAM-treated aluminum and hafnium oxide dielectrics (contact angles >100) through fine-tuning of the interfacial tension at the polymer-dielectric interface. This approach enables the processing and detailed characterization of near-amorphous (indacenodithiophene-cobenzothiadiazole) as well as semicrystalline (poly(2,5-bis(2-octyldodecyl)-3,6-di(thiophen-2-yl)diketopyrrolo[3,4-c]pyrrole-1,4-dione-alt-thieno[3,2-b]thiophen)) polymer semiconductors. We demonstrate polymer transistors that exhibit high on-currents and field-independent, charge carrier mobilities of 0.8 cm2 V−1s−1 at low operating voltages (<3 V).
{"title":"Low-voltage polymer transistors on hydrophobic dielectrics and surfaces","authors":"U. Kraft, M. Nikolka, Ging-Ji Nathan Wang, Yeongin Kim, R. Pfattner, Maryam Alsufyani, Iain McCulloch, B. Murmann, Z. Bao","doi":"10.1088/2515-7639/acb7a1","DOIUrl":"https://doi.org/10.1088/2515-7639/acb7a1","url":null,"abstract":"A set of unique features, including large-area solution processing on flexible and stretchable substrates, make polymer semiconductors a promising material choice for a range of state-of-the-art applications in electronics, optoelectronics and sensing. Yet, an inherent weakness of polymer semiconductors remains their low dielectric constants, increasing their susceptibility toward unscreened dipoles. These dipoles are particularly prevalent at polymer-dielectric interfaces with high-k dielectrics, which are essential for the operation of devices such as low-voltage field-effect transistors. This shortcoming can be addressed by using self-assembled monolayers (SAMs) to passivate surfaces that impact charge transport. However, SAM-treatment also increases the hydrophobicity of surfaces and therefore poses a challenge for subsequent solution processing steps and complex packaging of devices. Here, we report low-voltage polymer transistors processed by spin coating of the polymer semiconductors on highly hydrophobic SAM-treated aluminum and hafnium oxide dielectrics (contact angles >100) through fine-tuning of the interfacial tension at the polymer-dielectric interface. This approach enables the processing and detailed characterization of near-amorphous (indacenodithiophene-cobenzothiadiazole) as well as semicrystalline (poly(2,5-bis(2-octyldodecyl)-3,6-di(thiophen-2-yl)diketopyrrolo[3,4-c]pyrrole-1,4-dione-alt-thieno[3,2-b]thiophen)) polymer semiconductors. We demonstrate polymer transistors that exhibit high on-currents and field-independent, charge carrier mobilities of 0.8 cm2 V−1s−1 at low operating voltages (<3 V).","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83334192","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 : 2023-03-02DOI: 10.1088/2515-7639/acc099
Yusuf Zuntu Abdullahi, Rabia Çağlayan, A. Mogulkoc, Y. Mogulkoc, F. Ersan
Ultrawide band gap materials have numerous potential applications in deep ultraviolet optoelectronics, as well as next-generation high-power and radio frequency electronics. Through the first-principles calculations based on density functional theory calculations, we demonstrate that the As2O3 bulk and monolayer structures have excellent energetic, mechanical, and thermal stabilities. The bulk and monolayer of As2O3 come in two distinct structures, namely st1-As2O3, and st2-As2O3. We show that the st1-As2O3 and st2-As2O3 monolayer and bilayer could be mechanically exfoliated from their bulk material and found that the cleavage energy values are significantly lower than those reported for similarly layered materials. By performing Perdew–Burke–Ernzerhof (PBE) and Heyd–Scuseria–Ernzerhof (HSE06) band structure calculations, we found that the bulk and monolayers of As2O3 structures exhibit wide (PBE) and ultra-wide (HSE06) indirect band gaps. We further evaluate the As2O3 layered thickness-dependent band gaps and found that band gap decreases uniformly as the number of st1-As2O3 and st2-As2O3 layers increases. Our findings demonstrate the potential of the As2O3 structures for the future design of ultra-wide band gap semiconductor electronic devices.
{"title":"New stable ultrawide bandgap As2O3 semiconductor materials","authors":"Yusuf Zuntu Abdullahi, Rabia Çağlayan, A. Mogulkoc, Y. Mogulkoc, F. Ersan","doi":"10.1088/2515-7639/acc099","DOIUrl":"https://doi.org/10.1088/2515-7639/acc099","url":null,"abstract":"Ultrawide band gap materials have numerous potential applications in deep ultraviolet optoelectronics, as well as next-generation high-power and radio frequency electronics. Through the first-principles calculations based on density functional theory calculations, we demonstrate that the As2O3 bulk and monolayer structures have excellent energetic, mechanical, and thermal stabilities. The bulk and monolayer of As2O3 come in two distinct structures, namely st1-As2O3, and st2-As2O3. We show that the st1-As2O3 and st2-As2O3 monolayer and bilayer could be mechanically exfoliated from their bulk material and found that the cleavage energy values are significantly lower than those reported for similarly layered materials. By performing Perdew–Burke–Ernzerhof (PBE) and Heyd–Scuseria–Ernzerhof (HSE06) band structure calculations, we found that the bulk and monolayers of As2O3 structures exhibit wide (PBE) and ultra-wide (HSE06) indirect band gaps. We further evaluate the As2O3 layered thickness-dependent band gaps and found that band gap decreases uniformly as the number of st1-As2O3 and st2-As2O3 layers increases. Our findings demonstrate the potential of the As2O3 structures for the future design of ultra-wide band gap semiconductor electronic devices.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74180845","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}
In recent years, hafnia-based ferroelectrics have attracted enormous attention due to their capability of maintaining ferroelectricity below 10 nm thickness and excellent compatibility with microelectronics flow lines. However, the physical origin of their ferroelectricity is still not fully clear, although it is commonly attributed to a polar Pca21 orthorhombic phase. The high-temperature paraelectric phases (the tetragonal phase or the cubic phase) do not possess a soft mode at the Brillouin zone center, thus the ferroelectric distortion has to be explained in terms of trilinear coupling among three phonon modes in the tetragonal phase. It is necessary to explore new materials with possible ferroelectricity due to the polar Pca21 phase, which in turn should be very helpful in evaluating the microscopic theory for ferroelectric hafnia. In this work, based on the idea of the Materials Genome Engineering, a series of hafnia-like ferroelectrics have been found, exemplified by LaSeCl, LaSeBr, LuOF and YOF, which possess adequate spontaneous polarization values and also relatively favorable free energies for the polar phase. Their common features and individual differences are discussed in detail. In particular, a promising potential ferroelectric material, Pca21 phase LuOF, is predicted and recommended for further experimental synthesis and investigation.
{"title":"In search of Pca21 phase ferroelectrics","authors":"Ge‐Qi Mao, J. Yuan, Kanhao Xue, Jinhai Huang, Shengxin Yang, Xiangshui Miao","doi":"10.1088/2515-7639/acbee2","DOIUrl":"https://doi.org/10.1088/2515-7639/acbee2","url":null,"abstract":"In recent years, hafnia-based ferroelectrics have attracted enormous attention due to their capability of maintaining ferroelectricity below 10 nm thickness and excellent compatibility with microelectronics flow lines. However, the physical origin of their ferroelectricity is still not fully clear, although it is commonly attributed to a polar Pca21 orthorhombic phase. The high-temperature paraelectric phases (the tetragonal phase or the cubic phase) do not possess a soft mode at the Brillouin zone center, thus the ferroelectric distortion has to be explained in terms of trilinear coupling among three phonon modes in the tetragonal phase. It is necessary to explore new materials with possible ferroelectricity due to the polar Pca21 phase, which in turn should be very helpful in evaluating the microscopic theory for ferroelectric hafnia. In this work, based on the idea of the Materials Genome Engineering, a series of hafnia-like ferroelectrics have been found, exemplified by LaSeCl, LaSeBr, LuOF and YOF, which possess adequate spontaneous polarization values and also relatively favorable free energies for the polar phase. Their common features and individual differences are discussed in detail. In particular, a promising potential ferroelectric material, Pca21 phase LuOF, is predicted and recommended for further experimental synthesis and investigation.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78890413","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 : 2023-02-23DOI: 10.1088/2515-7639/acbe69
A. Ektarawong, E. Johansson, T. Pakornchote, T. Bovornratanaraks, B. Alling
Thermodynamic stability as well as structural, electronic, and elastic properties of boron-deficient AlB2-type tantalum diborides, which is designated as α− TaB 2−x , due to the presence of vacancies at its boron sublattice are studied via first-principles calculations. The results reveal that α− TaB 2−x , where 0.167 ≲x≲ 0.25, is thermodynamically stable even at absolute zero. On the other hand, the shear and Young’s moduli as well as the hardness of stable α− TaB 2−x are predicted to be superior as compared to those of α− TaB2. The changes in the relative stability and also the elastic properties of α− TaB 2−x with respect to those of α− TaB2 can be explained by the competitive effect between the decrease in the number of electrons filling in the antibonding states of α− TaB2 and the increase in the number of broken bonds around the vacancies, both induced by the increase in the concentration of boron vacancies. A good agreement between our calculated lattice parameters, elastic moduli and hardness of α− TaB 2−x and the experimentally measured data of as-synthesized AlB2-type tantalum diborides with the claimed composition of TaB ∼2 , available in the literature, suggests that, instead of being a line compound with a stoichiometric composition of TaB2, AlB2-type tantalum diboride is readily boron-deficient, and its stable composition in equilibrium may be ranging at least from TaB ∼1.833 to TaB ∼1.75 . Furthermore, the substitution of vacancies for boron atoms in α− TaB2 is responsible for destabilization of WB2-type tantalum diboride and orthorhombic Ta2B3, predicted in the previous theoretical studies to be thermodynamically stable in the Ta−B system, and it thus enables the interpretation of why the two compounds have never been realized in actual experiments.
{"title":"Boron vacancy-driven thermodynamic stabilization and improved mechanical properties of AlB2-type tantalum diborides as revealed by first-principles calculations","authors":"A. Ektarawong, E. Johansson, T. Pakornchote, T. Bovornratanaraks, B. Alling","doi":"10.1088/2515-7639/acbe69","DOIUrl":"https://doi.org/10.1088/2515-7639/acbe69","url":null,"abstract":"Thermodynamic stability as well as structural, electronic, and elastic properties of boron-deficient AlB2-type tantalum diborides, which is designated as α− TaB 2−x , due to the presence of vacancies at its boron sublattice are studied via first-principles calculations. The results reveal that α− TaB 2−x , where 0.167 ≲x≲ 0.25, is thermodynamically stable even at absolute zero. On the other hand, the shear and Young’s moduli as well as the hardness of stable α− TaB 2−x are predicted to be superior as compared to those of α− TaB2. The changes in the relative stability and also the elastic properties of α− TaB 2−x with respect to those of α− TaB2 can be explained by the competitive effect between the decrease in the number of electrons filling in the antibonding states of α− TaB2 and the increase in the number of broken bonds around the vacancies, both induced by the increase in the concentration of boron vacancies. A good agreement between our calculated lattice parameters, elastic moduli and hardness of α− TaB 2−x and the experimentally measured data of as-synthesized AlB2-type tantalum diborides with the claimed composition of TaB ∼2 , available in the literature, suggests that, instead of being a line compound with a stoichiometric composition of TaB2, AlB2-type tantalum diboride is readily boron-deficient, and its stable composition in equilibrium may be ranging at least from TaB ∼1.833 to TaB ∼1.75 . Furthermore, the substitution of vacancies for boron atoms in α− TaB2 is responsible for destabilization of WB2-type tantalum diboride and orthorhombic Ta2B3, predicted in the previous theoretical studies to be thermodynamically stable in the Ta−B system, and it thus enables the interpretation of why the two compounds have never been realized in actual experiments.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85200096","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 : 2023-02-23DOI: 10.1088/2515-7639/acd1b7
D. Fernández-Fernández, Jordi Pic'o-Cort'es, Sergio Vela Liñán, G. Platero
We investigate the effect of spin–orbit interaction on the intra- and interdot particle dynamics of a double quantum dot (QD) under ac electric fields. The former is modeled as an effective ac magnetic field that produces electric-dipole spin resonance transitions, while the latter is introduced via spin-flip tunneling amplitudes. We observe the appearance of non-trivial spin-polarized dark states (DSs), arising from an ac-induced interference between photo-assisted spin-conserving and spin-flip tunneling processes. These DSs can be employed to precisely measure the spin–orbit coupling in QD systems. Furthermore, we show that the interplay between photo-assisted transitions and spin-flip tunneling enables the system to operate as a highly tunable spin filter. Finally, we investigate the operation of the system as a resonant flopping-mode qubit for arbitrary ac voltage amplitudes, allowing for high tunability and enhanced qubit control possibilities.
{"title":"Photo-assisted spin transport in double quantum dots with spin–orbit interaction","authors":"D. Fernández-Fernández, Jordi Pic'o-Cort'es, Sergio Vela Liñán, G. Platero","doi":"10.1088/2515-7639/acd1b7","DOIUrl":"https://doi.org/10.1088/2515-7639/acd1b7","url":null,"abstract":"We investigate the effect of spin–orbit interaction on the intra- and interdot particle dynamics of a double quantum dot (QD) under ac electric fields. The former is modeled as an effective ac magnetic field that produces electric-dipole spin resonance transitions, while the latter is introduced via spin-flip tunneling amplitudes. We observe the appearance of non-trivial spin-polarized dark states (DSs), arising from an ac-induced interference between photo-assisted spin-conserving and spin-flip tunneling processes. These DSs can be employed to precisely measure the spin–orbit coupling in QD systems. Furthermore, we show that the interplay between photo-assisted transitions and spin-flip tunneling enables the system to operate as a highly tunable spin filter. Finally, we investigate the operation of the system as a resonant flopping-mode qubit for arbitrary ac voltage amplitudes, allowing for high tunability and enhanced qubit control possibilities.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74223617","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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