Pub Date : 2023-07-10DOI: 10.1088/2515-7639/ace5df
Sophie Marcelja, Lisanne Demelius, T. A. Ali, Margherita Aghito, Fabian Muralter, G. H. Rodríguez, M. Kräuter, K. Unger, Lukas Wolfsberger, A. Coclite
Soft biomaterials are a crucial component in several application fields. They are used, for example, in biomedical implants, biosensors, drug delivery systems as well as in tissue engineering. In parallel to extensive ongoing efforts to synthesize new materials, the development of means to tailor the materials’ surface properties and thus their interaction with the environment is an important field of research. This has led to the emergence of several surface modification techniques that enable the exploitation of biomaterials in a broader range of technologies. In particular, the use of functional thin films can enable a plethora of biomedical applications by combining advantageous bulk properties of the substrate (e.g. flexibility, lightweight, structural strength) with tailored surface properties of the thin film (e.g. enhancing/prevention of cell proliferation, controlled drug release). For some biomedical applications, thin films can also be the main functional components, e.g. in biosensors. The present review focuses on recent developments in the applications of soft biomaterials based on thin films deposited from the vapor phase. In the field of soft biomaterials, the possibility of depositing from the vapor phase—without the need for any solvents—offers the unprecedented benefit that no toxic leachables are included in the biomaterial. Further, due to the complete lack of solvents and chemicals overall being used in small quantities only, depositing thin films from the vapor phase can be a more sustainable choice than other techniques that are commonly used.
{"title":"Applications of soft biomaterials based on organic and hybrid thin films deposited from the vapor phase","authors":"Sophie Marcelja, Lisanne Demelius, T. A. Ali, Margherita Aghito, Fabian Muralter, G. H. Rodríguez, M. Kräuter, K. Unger, Lukas Wolfsberger, A. Coclite","doi":"10.1088/2515-7639/ace5df","DOIUrl":"https://doi.org/10.1088/2515-7639/ace5df","url":null,"abstract":"Soft biomaterials are a crucial component in several application fields. They are used, for example, in biomedical implants, biosensors, drug delivery systems as well as in tissue engineering. In parallel to extensive ongoing efforts to synthesize new materials, the development of means to tailor the materials’ surface properties and thus their interaction with the environment is an important field of research. This has led to the emergence of several surface modification techniques that enable the exploitation of biomaterials in a broader range of technologies. In particular, the use of functional thin films can enable a plethora of biomedical applications by combining advantageous bulk properties of the substrate (e.g. flexibility, lightweight, structural strength) with tailored surface properties of the thin film (e.g. enhancing/prevention of cell proliferation, controlled drug release). For some biomedical applications, thin films can also be the main functional components, e.g. in biosensors. The present review focuses on recent developments in the applications of soft biomaterials based on thin films deposited from the vapor phase. In the field of soft biomaterials, the possibility of depositing from the vapor phase—without the need for any solvents—offers the unprecedented benefit that no toxic leachables are included in the biomaterial. Further, due to the complete lack of solvents and chemicals overall being used in small quantities only, depositing thin films from the vapor phase can be a more sustainable choice than other techniques that are commonly used.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87097647","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 : 2023-07-03DOI: 10.1088/2515-7639/ace381
Abhishek Gupta, R. Thevamaran
Recent progress in non-Hermitian physics and the notion of exceptional point (EP) degeneracies in elastodynamics have led to the development of novel metamaterials for the control of elastic wave propagation, hypersensitive sensors, and actuators. The emergence of EPs in a parity-time symmetric system relies on judiciously engineered balanced gain and loss mechanisms. Creating gain requires complex circuits and amplification mechanisms, making engineering applications challenging. Here, we report strategies to achieve EPs in passive non-Hermitian elastodynamic systems with differential loss derived from viscoelastic materials. We compare different viscoelastic material models and show that the EP emerges only when the frequency-dependent loss-tangent of the viscoelastic material remains nearly constant in the frequency range of operation. This type of loss tangent occurs in materials that undergo stress-relaxation over a broad spectrum of relaxation times, for example, materials that follow the Kelvin–Voigt fractional derivative (KVFD) model. Using dynamic mechanical analysis, we show that a few common viscoelastic elastomers, such as polydimethylsiloxane and polyurethane rubber, follow the KVFD behavior such that the loss tangent becomes almost constant after a particular frequency. The material models we present and the demonstration of the potential of a widely available material system in creating EPs pave the way for developing non-Hermitian metamaterials with hypersensitivity to perturbations or enhanced emissivity.
{"title":"Requisites on material viscoelasticity for exceptional points in passive dynamical systems","authors":"Abhishek Gupta, R. Thevamaran","doi":"10.1088/2515-7639/ace381","DOIUrl":"https://doi.org/10.1088/2515-7639/ace381","url":null,"abstract":"Recent progress in non-Hermitian physics and the notion of exceptional point (EP) degeneracies in elastodynamics have led to the development of novel metamaterials for the control of elastic wave propagation, hypersensitive sensors, and actuators. The emergence of EPs in a parity-time symmetric system relies on judiciously engineered balanced gain and loss mechanisms. Creating gain requires complex circuits and amplification mechanisms, making engineering applications challenging. Here, we report strategies to achieve EPs in passive non-Hermitian elastodynamic systems with differential loss derived from viscoelastic materials. We compare different viscoelastic material models and show that the EP emerges only when the frequency-dependent loss-tangent of the viscoelastic material remains nearly constant in the frequency range of operation. This type of loss tangent occurs in materials that undergo stress-relaxation over a broad spectrum of relaxation times, for example, materials that follow the Kelvin–Voigt fractional derivative (KVFD) model. Using dynamic mechanical analysis, we show that a few common viscoelastic elastomers, such as polydimethylsiloxane and polyurethane rubber, follow the KVFD behavior such that the loss tangent becomes almost constant after a particular frequency. The material models we present and the demonstration of the potential of a widely available material system in creating EPs pave the way for developing non-Hermitian metamaterials with hypersensitivity to perturbations or enhanced emissivity.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74611730","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 : 2023-07-01DOI: 10.1088/2515-7639/acdfff
Giovanna Feraco, O. D. Luca, Ali Syari’ati, Sardar Hameed, A. A. El Yumin, Jianting Ye, R. Agostino, P. Rudolf
Vacancies in atomically thin molybdenum disulphide play an essential role in controlling its optical and electronic properties, which are crucial for applications in sensorics, catalysis or electronics. For this reason, defect engineering employing thiol-terminated molecules is used to heal and/or functionalise defective nanosheets. In this work, chemical vapour deposition-grown MoS2 with different defect densities was functionalised with three molecules: 4-aminothiophenol (ATP), biphenyl-4-thiol (BPT) and 4-nitrothiophenol (NTP). The molecules’ efficacy in functionalising MoS2 was probed by x-ray photoelectron, Raman and photoluminescence (PL) spectroscopy. The results show that exposing a defective single layer of MoS2 to either ATP, BPT or NTP molecules heals the defects, however the chemical structure of these molecules affects the optical response and only for BPT the PL intensity increases.
{"title":"Different healing characteristics of thiol-bearing molecules on CVD-grown MoS2","authors":"Giovanna Feraco, O. D. Luca, Ali Syari’ati, Sardar Hameed, A. A. El Yumin, Jianting Ye, R. Agostino, P. Rudolf","doi":"10.1088/2515-7639/acdfff","DOIUrl":"https://doi.org/10.1088/2515-7639/acdfff","url":null,"abstract":"Vacancies in atomically thin molybdenum disulphide play an essential role in controlling its optical and electronic properties, which are crucial for applications in sensorics, catalysis or electronics. For this reason, defect engineering employing thiol-terminated molecules is used to heal and/or functionalise defective nanosheets. In this work, chemical vapour deposition-grown MoS2 with different defect densities was functionalised with three molecules: 4-aminothiophenol (ATP), biphenyl-4-thiol (BPT) and 4-nitrothiophenol (NTP). The molecules’ efficacy in functionalising MoS2 was probed by x-ray photoelectron, Raman and photoluminescence (PL) spectroscopy. The results show that exposing a defective single layer of MoS2 to either ATP, BPT or NTP molecules heals the defects, however the chemical structure of these molecules affects the optical response and only for BPT the PL intensity increases.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76355911","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 : 2023-07-01DOI: 10.1088/2515-7639/ace21a
Ashley S. Dale, Saeed Yazdani, T. K. Ekanayaka, Esha Mishra, Yuchen Hu, P. Dowben, J. Freeland, Jian Zhang, R. Cheng
In this work, we provide clear evidence of magnetic anisotropy in the local orbital moment of a molecular thin film based on the SCO complex [Fe(H2B(pz)2)2(bipy)] (pz = pyrazol−1−yl, bipy = 2,2′−bipyridine). Field dependent x-ray magnetic circular dichroism measurements indicate that the magnetic easy axis for the orbital moment is along the surface normal direction. Along with the presence of a critical field, our observation points to the existence of an anisotropic energy barrier in the high-spin state. The estimated nonzero coupling constant of ∼2.47 × 10−5 eV molecule−1 indicates that the observed magnetocrystalline anisotropy is mostly due to spin–orbit coupling. The spin- and orbital-component anisotropies are determined to be 30.9 and 5.04 meV molecule−1, respectively. Furthermore, the estimated g factor in the range of 2.2–2.45 is consistent with the expected values. This work has paved the way for an understanding of the spin-state-switching mechanism in the presence of magnetic perturbations.
{"title":"Direct observation of the magnetic anisotropy of an Fe(II) spin crossover molecular thin film","authors":"Ashley S. Dale, Saeed Yazdani, T. K. Ekanayaka, Esha Mishra, Yuchen Hu, P. Dowben, J. Freeland, Jian Zhang, R. Cheng","doi":"10.1088/2515-7639/ace21a","DOIUrl":"https://doi.org/10.1088/2515-7639/ace21a","url":null,"abstract":"In this work, we provide clear evidence of magnetic anisotropy in the local orbital moment of a molecular thin film based on the SCO complex [Fe(H2B(pz)2)2(bipy)] (pz = pyrazol−1−yl, bipy = 2,2′−bipyridine). Field dependent x-ray magnetic circular dichroism measurements indicate that the magnetic easy axis for the orbital moment is along the surface normal direction. Along with the presence of a critical field, our observation points to the existence of an anisotropic energy barrier in the high-spin state. The estimated nonzero coupling constant of ∼2.47 × 10−5 eV molecule−1 indicates that the observed magnetocrystalline anisotropy is mostly due to spin–orbit coupling. The spin- and orbital-component anisotropies are determined to be 30.9 and 5.04 meV molecule−1, respectively. Furthermore, the estimated g factor in the range of 2.2–2.45 is consistent with the expected values. This work has paved the way for an understanding of the spin-state-switching mechanism in the presence of magnetic perturbations.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86891539","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 : 2023-06-30DOI: 10.1088/2515-7639/acdeaa
Cara-Lena Nies, M. Nolan
Progress in semiconductor devices, which has enabled the information and communications technology explosion of the 21st century, has been driven by Moore’s Law and the accompanying aggressive scaling of transistors. However, it is now acknowledged that the currently used copper interconnects are becoming a bottleneck in sub-nm scaling. Semiconductor devices require a diffusion barrier and a seed layer in the volume available to the interconnect metal. This then limits the minimum size of the interconnect and copper suffers from a preference to form 3D islands which are non-conducting rather than conducting films. Therefore there is a pressing need to either replace copper, which has its own difficulties, or to reduce the volume taken up by the diffusion barrier and liner; ideally finding a single material displaying both properties is needed. We have previously shown that incorporation of Ru into the surface layer of TaN is a strong alternative to the usual TaN/Ta or TaN/Ru stacks. In this work we study other possible metals that can be incorporated into TaN, namely Co and W, which are less expensive and critical than Ru and can potentially outperform it. Our first principles density functional theory results from static relaxations and ab initio molecular dynamics show that there are several compositions of both Co- and W-doped TaN which should promote growth of 2D copper interconnects without compromising the barrier properties of TaN. With this selection of materials it should be possible to design new experimental processes that promote downscaled copper interconnects for the next generation of electronic devices. Additionally, our work presents an improved method towards prediction of thin film morphology on a given substrate, which can be of use for a variety of materials science applications.
{"title":"Incorporation of tungsten or cobalt into TaN barrier layers controls morphology of deposited copper","authors":"Cara-Lena Nies, M. Nolan","doi":"10.1088/2515-7639/acdeaa","DOIUrl":"https://doi.org/10.1088/2515-7639/acdeaa","url":null,"abstract":"Progress in semiconductor devices, which has enabled the information and communications technology explosion of the 21st century, has been driven by Moore’s Law and the accompanying aggressive scaling of transistors. However, it is now acknowledged that the currently used copper interconnects are becoming a bottleneck in sub-nm scaling. Semiconductor devices require a diffusion barrier and a seed layer in the volume available to the interconnect metal. This then limits the minimum size of the interconnect and copper suffers from a preference to form 3D islands which are non-conducting rather than conducting films. Therefore there is a pressing need to either replace copper, which has its own difficulties, or to reduce the volume taken up by the diffusion barrier and liner; ideally finding a single material displaying both properties is needed. We have previously shown that incorporation of Ru into the surface layer of TaN is a strong alternative to the usual TaN/Ta or TaN/Ru stacks. In this work we study other possible metals that can be incorporated into TaN, namely Co and W, which are less expensive and critical than Ru and can potentially outperform it. Our first principles density functional theory results from static relaxations and ab initio molecular dynamics show that there are several compositions of both Co- and W-doped TaN which should promote growth of 2D copper interconnects without compromising the barrier properties of TaN. With this selection of materials it should be possible to design new experimental processes that promote downscaled copper interconnects for the next generation of electronic devices. Additionally, our work presents an improved method towards prediction of thin film morphology on a given substrate, which can be of use for a variety of materials science applications.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78922365","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 : 2023-06-26DOI: 10.1088/2515-7639/acdf22
S. Gallego
Proximity effects can be used to introduce spin–orbit interactions in magnetic metallic layers in contact to a heavy metal (HM). This well known phenomenon has been exploited to induce chiral spin textures at Co ultrathin films, where the left- or right- handedness can be tuned by the HM layer position, based on the broken inversion symmetry of the film and the existence of an additive interface effect. Here we show that structural and chemical features introducing further symmetry reductions can be added to this scenario ultimately enabling control over the definition of a unique winding sense. We focus on 2Ni/Co heterostructures and Bi, a scarcely explored HM metal of large size, to combine a chemically inhomogeneous ferromagnetic stack along the normal to the surface with in-plane asymmetries. Our results are contrasted to 2Co layers combined with Ir.
{"title":"Towards control of the chirality sign at ultrathin metal films: Bi at 2Ni/Co","authors":"S. Gallego","doi":"10.1088/2515-7639/acdf22","DOIUrl":"https://doi.org/10.1088/2515-7639/acdf22","url":null,"abstract":"Proximity effects can be used to introduce spin–orbit interactions in magnetic metallic layers in contact to a heavy metal (HM). This well known phenomenon has been exploited to induce chiral spin textures at Co ultrathin films, where the left- or right- handedness can be tuned by the HM layer position, based on the broken inversion symmetry of the film and the existence of an additive interface effect. Here we show that structural and chemical features introducing further symmetry reductions can be added to this scenario ultimately enabling control over the definition of a unique winding sense. We focus on 2Ni/Co heterostructures and Bi, a scarcely explored HM metal of large size, to combine a chemically inhomogeneous ferromagnetic stack along the normal to the surface with in-plane asymmetries. Our results are contrasted to 2Co layers combined with Ir.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81165518","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 : 2023-06-02DOI: 10.1088/2515-7639/acdaf8
G. Barrera, P. Allia, P. Tiberto
An innovative method is proposed to determine the most important magnetic properties of bioapplication-oriented magnetic nanomaterials exploiting the connection between hysteresis loop and frequency spectrum of magnetization. Owing to conceptual and practical simplicity, the method may result in a substantial advance in the optimization of magnetic nanomaterials for use in precision medicine. The techniques of frequency analysis of the magnetization currently applied to nanomaterials both in vitro and in vivo usually give a limited, qualitative picture of the effects of the active biological environment, and have to be complemented by direct measurement of the hysteresis loop. We show that the very same techniques can be used to convey all the information needed by present-day biomedical applications without the necessity of doing conventional magnetic measurements in the same experimental conditions. The spectral harmonics obtained analysing the response of a magnetic tracer in frequency, as in magnetic particle spectroscopy/imaging, are demonstrated to lead to a precise reconstruction of the hysteresis loop, whose most important parameters (loop’s area, magnetic remanence and coercive field) are directly obtained through transformation formulas based on simple manipulation of the harmonics amplitudes and phases. The validity of the method is experimentally verified on various magnetic nanomaterials for bioapplications submitted to ac magnetic fields of different amplitude, frequency and waveform. In all cases, the experimental data taken in the frequency domain exactly reproduce the magnetic properties obtained from conventional magnetic measurements.
{"title":"From spectral analysis to hysteresis loops: a breakthrough in the optimization of magnetic nanomaterials for bioapplications","authors":"G. Barrera, P. Allia, P. Tiberto","doi":"10.1088/2515-7639/acdaf8","DOIUrl":"https://doi.org/10.1088/2515-7639/acdaf8","url":null,"abstract":"An innovative method is proposed to determine the most important magnetic properties of bioapplication-oriented magnetic nanomaterials exploiting the connection between hysteresis loop and frequency spectrum of magnetization. Owing to conceptual and practical simplicity, the method may result in a substantial advance in the optimization of magnetic nanomaterials for use in precision medicine. The techniques of frequency analysis of the magnetization currently applied to nanomaterials both in vitro and in vivo usually give a limited, qualitative picture of the effects of the active biological environment, and have to be complemented by direct measurement of the hysteresis loop. We show that the very same techniques can be used to convey all the information needed by present-day biomedical applications without the necessity of doing conventional magnetic measurements in the same experimental conditions. The spectral harmonics obtained analysing the response of a magnetic tracer in frequency, as in magnetic particle spectroscopy/imaging, are demonstrated to lead to a precise reconstruction of the hysteresis loop, whose most important parameters (loop’s area, magnetic remanence and coercive field) are directly obtained through transformation formulas based on simple manipulation of the harmonics amplitudes and phases. The validity of the method is experimentally verified on various magnetic nanomaterials for bioapplications submitted to ac magnetic fields of different amplitude, frequency and waveform. In all cases, the experimental data taken in the frequency domain exactly reproduce the magnetic properties obtained from conventional magnetic measurements.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80633808","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 : 2023-05-25DOI: 10.1088/2515-7639/acd8f3
Seyedeh Alieh Kazemi, Samuel Akinlolu Ogunkunle, Oscar J. Allen, W. Wen, Alan Wee-Chung Liew, Shiwei Yin, Yun Wang
Halogenated MXenes have been experimentally demonstrated to be promising two-dimensional materials for a wide range of applicability. However, their physicochemical properties are largely unknown at the atomic level. In this study, we applied density functional theory (DFT) to theoretically investigate the halogenation effects on the structural, electronic, and mechanical characteristics of Ti3C2, which is the most studied MXene material. Three atomic configurations with different adsorption sites for four kinds of halogen terminals (fluorine, chlorine, bromine, and iodine) were considered. Our DFT results reveal that the adsorption site of terminals has a considerable impact on the properties of MXene. This can be ascribed to the different coordination environments of the surface Ti atoms, which change d-orbital splitting configurations of surface Ti atoms and the stabilities of systems. According to the density of states, crystal orbital Hamilton population, and charge analyses, all the considered halogenated MXenes are metallic. The electronic and mechanical properties of the halogenated MXenes are strongly dependent on the electronegativity of the halogen terminal group. The Ti–F bond has more ionic characteristics, which causes Ti3C2F2 mechanically behave in a more ductile manner. Our DFT results, therefore, suggest that the physicochemical properties of MXenes can be tuned for practical applications by selecting specific halogen terminal groups.
{"title":"Halogenation effect on physicochemical properties of Ti3C2 MXenes","authors":"Seyedeh Alieh Kazemi, Samuel Akinlolu Ogunkunle, Oscar J. Allen, W. Wen, Alan Wee-Chung Liew, Shiwei Yin, Yun Wang","doi":"10.1088/2515-7639/acd8f3","DOIUrl":"https://doi.org/10.1088/2515-7639/acd8f3","url":null,"abstract":"Halogenated MXenes have been experimentally demonstrated to be promising two-dimensional materials for a wide range of applicability. However, their physicochemical properties are largely unknown at the atomic level. In this study, we applied density functional theory (DFT) to theoretically investigate the halogenation effects on the structural, electronic, and mechanical characteristics of Ti3C2, which is the most studied MXene material. Three atomic configurations with different adsorption sites for four kinds of halogen terminals (fluorine, chlorine, bromine, and iodine) were considered. Our DFT results reveal that the adsorption site of terminals has a considerable impact on the properties of MXene. This can be ascribed to the different coordination environments of the surface Ti atoms, which change d-orbital splitting configurations of surface Ti atoms and the stabilities of systems. According to the density of states, crystal orbital Hamilton population, and charge analyses, all the considered halogenated MXenes are metallic. The electronic and mechanical properties of the halogenated MXenes are strongly dependent on the electronegativity of the halogen terminal group. The Ti–F bond has more ionic characteristics, which causes Ti3C2F2 mechanically behave in a more ductile manner. Our DFT results, therefore, suggest that the physicochemical properties of MXenes can be tuned for practical applications by selecting specific halogen terminal groups.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91214675","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 : 2023-05-25DOI: 10.1088/2515-7639/acd8f2
Ramasamy Murugesan, E. Janssens, J. van de Vondel, V. Afanas’ev, M. Houssa
The size dependent interaction of Cu n (n = 1‒5) clusters with pristine and defective (C-vacancy) graphene is studied by employing density functional theory. The computed binding energies are in the range of ∼0.5 eV for pristine graphene and ∼3.5 eV for defective graphene, indicating a much stronger interaction in the later system. The induced spin–orbit coupling interaction, due to the proximity of the Cu n cluster, is studied with non-collinear spin-polarized simulations. The clusters cause a spin splitting in the order of few meV. The resultant low energy bands spin textures are also computed, and a spin–valley coupling in the case of even atom clusters on pristine graphene is predicted, leading to the emergence of a spin lifetime anisotropy. For defective graphene, a complete out-of-plane spin texture and a large spin splitting of 40–100 meV is obtained for Cu n (n = 1, 2, 3, 5) clusters due to local magnetic moment. On the other hand, for Cu4/defective graphene, having no net magnetic moment, the spin–valley coupling prevails close to the band edges.
利用密度泛函理论研究了Cu n (n = 1-5)团簇与原始和缺陷(c -空位)石墨烯的尺寸依赖相互作用。计算得到的原始石墨烯的结合能在~ 0.5 eV，缺陷石墨烯的结合能在~ 3.5 eV，表明在后期系统中有更强的相互作用。利用非共线自旋极化模拟研究了Cu - n簇邻近引起的自旋-轨道耦合相互作用。这些团簇引起了几个meV量级的自旋分裂。由此产生的低能带自旋织构也进行了计算，并预测了原始石墨烯上均匀原子团簇情况下的自旋谷耦合，导致自旋寿命各向异性的出现。对于缺陷石墨烯，由于局部磁矩的作用，Cu n (n = 1,2,3,5)团簇获得了完整的面外自旋织构和40-100 meV的大自旋分裂。另一方面，对于Cu4/缺陷石墨烯，没有净磁矩，自旋谷耦合在带边缘附近盛行。
{"title":"Tuning the spin texture of graphene with size-specific Cu n clusters: a first-principles study","authors":"Ramasamy Murugesan, E. Janssens, J. van de Vondel, V. Afanas’ev, M. Houssa","doi":"10.1088/2515-7639/acd8f2","DOIUrl":"https://doi.org/10.1088/2515-7639/acd8f2","url":null,"abstract":"The size dependent interaction of Cu n (n = 1‒5) clusters with pristine and defective (C-vacancy) graphene is studied by employing density functional theory. The computed binding energies are in the range of ∼0.5 eV for pristine graphene and ∼3.5 eV for defective graphene, indicating a much stronger interaction in the later system. The induced spin–orbit coupling interaction, due to the proximity of the Cu n cluster, is studied with non-collinear spin-polarized simulations. The clusters cause a spin splitting in the order of few meV. The resultant low energy bands spin textures are also computed, and a spin–valley coupling in the case of even atom clusters on pristine graphene is predicted, leading to the emergence of a spin lifetime anisotropy. For defective graphene, a complete out-of-plane spin texture and a large spin splitting of 40–100 meV is obtained for Cu n (n = 1, 2, 3, 5) clusters due to local magnetic moment. On the other hand, for Cu4/defective graphene, having no net magnetic moment, the spin–valley coupling prevails close to the band edges.","PeriodicalId":16520,"journal":{"name":"Journal of Nonlinear Optical Physics & Materials","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85497967","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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