Pub Date : 2024-09-20DOI: 10.1016/j.physb.2024.416548
A modified two-sublattice pseudospin model of NH4HSO4 ferroelectrics is proposed, which considers the displacement of sulfate groups in the two-minimum potential well as a pseudospin subsystem. The model takes into account the electrostrictive and piezoelectric coupling of the pseudospin and lattice subsystems. In the mean field approximation, the dielectric, piezoelectric, elastic and thermal characteristics of the crystal are calculated. A satisfactory quantitative description of the relevant experimental data has been obtained. Our model allowed us to describe the effect of hydrostatic pressure on the second order phase transition at the upper Curie point and the first order one at the lower Curie point. We have shown that the distinct first-order phase transition at the lower Curie point as well as the corresponding great changes in lattice strains can be caused by the strong electrostrictive coupling of the pseudospin and lattice subsystems.
{"title":"Dielectric, elastic, and thermal characteristics of NH4HSO4 ferroelectric within the framework of a two-sublattice pseudospin model","authors":"","doi":"10.1016/j.physb.2024.416548","DOIUrl":"10.1016/j.physb.2024.416548","url":null,"abstract":"<div><div>A modified two-sublattice pseudospin model of NH<sub>4</sub>HSO<sub>4</sub> ferroelectrics is proposed, which considers the displacement of sulfate groups in the two-minimum potential well as a pseudospin subsystem. The model takes into account the electrostrictive and piezoelectric coupling of the pseudospin and lattice subsystems. In the mean field approximation, the dielectric, piezoelectric, elastic and thermal characteristics of the crystal are calculated. A satisfactory quantitative description of the relevant experimental data has been obtained. Our model allowed us to describe the effect of hydrostatic pressure on the second order phase transition at the upper Curie point and the first order one at the lower Curie point. We have shown that the distinct first-order phase transition at the lower Curie point as well as the corresponding great changes in lattice strains can be caused by the strong electrostrictive coupling of the pseudospin and lattice subsystems.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-19DOI: 10.1016/j.physb.2024.416519
To address the current issue of complex coding metasurface structure and deficiency of independent phase control for distinct polarized light within the broadband range, we present a wavefront processing coding metasurface with independent dynamic control of circularly and linearly polarized. The results demonstrate that when VO2 is in the metallic state and circularly polarized (CP) is incident, the metasurface can achieve efficient broadband circular polarization conversion in the 0.48–1.19 THz range, with a relative bandwidth of 85.02 %. It can achieve full 0-2π phase coverage by leveraging the P-B phase principle. When VO2 is in the dielectric state and linearly polarized (LP) is incident, x-LP can attain full 0-2π phase coverage in the range of 1.54–1.60 THz and y-LP can reach full 0-2π phase coverage in the range of 0.65–1.05 THz, which can be adjusted independently. Through encoding and arranging the metasurface, abnormal reflection and vortex beam generation of different polarized light in the same device are realized.
{"title":"A wavefront processing coding metasurface with independent dynamic control of circularly and linearly polarized","authors":"","doi":"10.1016/j.physb.2024.416519","DOIUrl":"10.1016/j.physb.2024.416519","url":null,"abstract":"<div><div>To address the current issue of complex coding metasurface structure and deficiency of independent phase control for distinct polarized light within the broadband range, we present a wavefront processing coding metasurface with independent dynamic control of circularly and linearly polarized. The results demonstrate that when VO<sub>2</sub> is in the metallic state and circularly polarized (CP) is incident, the metasurface can achieve efficient broadband circular polarization conversion in the 0.48–1.19 THz range, with a relative bandwidth of 85.02 %. It can achieve full 0-2π phase coverage by leveraging the P-B phase principle. When VO<sub>2</sub> is in the dielectric state and linearly polarized (LP) is incident, <em>x</em>-LP can attain full 0-2π phase coverage in the range of 1.54–1.60 THz and <em>y</em>-LP can reach full 0-2π phase coverage in the range of 0.65–1.05 THz, which can be adjusted independently. Through encoding and arranging the metasurface, abnormal reflection and vortex beam generation of different polarized light in the same device are realized.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-19DOI: 10.1016/j.physb.2024.416551
Extensive investigations have been conducted on Mo-based MXenes due to their high superconducting temperatures (). This work theoretically reports strong electron–phonon coupling (EPC) and high (38 K) of 2H-MoN under biaxial stress, with excellent mechanical properties. EPC and are elucidated upon dynamically stable strain range. At 0% strain, EPC constant () and are 1.32 and 22.7 K, respectively. They are improved when subjected to biaxial stresses. Strong EPC with over 2.0 occurs at −4%, −2.5%, and 5% strains, yielding enhanced . The finding suggests that the energy levels of electronic bands at the Fermi level are enhanced by strain, which enhances EPC. Moreover, the impact of functional groups on superconductivity has been investigated. The ’s of MoNH and MoNO are reduced, and drops nearly to 20.0 and 0.9 K, respectively. This work provides an example of designing 2D superconductors by tuning atomic recipes and strain-dependent engineering.
{"title":"Strong electron–phonon coupling and predicted high superconducting transition temperature of MXenes revealed in 2H-Mo2N under biaxial stress","authors":"","doi":"10.1016/j.physb.2024.416551","DOIUrl":"10.1016/j.physb.2024.416551","url":null,"abstract":"<div><div>Extensive investigations have been conducted on Mo-based MXenes due to their high superconducting temperatures (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>). This work theoretically reports strong electron–phonon coupling (EPC) and high <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> (<span><math><mo>≈</mo></math></span>38 K) of 2H-Mo<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>N under biaxial stress, with excellent mechanical properties. EPC and <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> are elucidated upon dynamically stable strain range. At 0% strain, EPC constant (<span><math><mi>λ</mi></math></span>) and <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> are 1.32 and 22.7 K, respectively. They are improved when subjected to biaxial stresses. Strong EPC with <span><math><mi>λ</mi></math></span> over 2.0 occurs at −4%, −2.5%, and 5% strains, yielding enhanced <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>. The finding suggests that the energy levels of electronic bands at the Fermi level are enhanced by strain, which enhances EPC. Moreover, the impact of functional groups on superconductivity has been investigated. The <span><math><mi>λ</mi></math></span>’s of Mo<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>NH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> and Mo<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>NO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> are reduced, and <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> drops nearly to 20.0 and 0.9 K, respectively. This work provides an example of designing 2D superconductors by tuning atomic recipes and strain-dependent engineering.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-18DOI: 10.1016/j.physb.2024.416529
Ab initio calculations of the electronic structure and thermoelectric characteristics of low- and high-temperature phases of tin selenide, SnSe, with electronic and hole conductivity have been performed. It is shown that the calculations of thermoelectric properties on the basis of the Boltzmann-Onzager theory with consideration of carrier scattering on optical phonons lead to results in good agreement with experimental data. At temperatures below 600 K the modeling correctly reproduces the increased values of the figure-of-merit of electron-doped SnSe in comparison with almost stoichiometric or hole-doped selenide calculations. We explain anomalously high figure-of-merit values of the non-doped selenide at T > 600 K by the hole concentration increase due to oxidation of SnSe or the appearance of vacancies in the tin sublattice. For all the considered variants, i.e. for electron-doped low-temperature and high-temperature phases and low-temperature hole-doped phase, the modeling predicts the absence of figure-of-merit increase at exceeding some limiting concentration of current carriers.
对具有电子和空穴导电性的硒化锡（SnSe）低温和高温相的电子结构和热电特性进行了 Ab initio 计算。结果表明，在波尔兹曼-昂扎格理论的基础上，考虑到载流子对光学声子的散射，热电性能的计算结果与实验数据十分吻合。在低于 600 K 的温度下，建模正确地再现了电子掺杂的硒化锡与几乎原子序数或空穴掺杂的硒化物计算结果相比所增加的功率因数值。我们可以用 SnSe 氧化或锡亚晶格中出现空位导致空穴浓度增加来解释非掺杂硒化物在开氏 600 度时出现的异常高功率值。对于所考虑的所有变体，即电子掺杂的低温相、高温相和低温空穴掺杂相，建模预测在电流载流子浓度超过某个极限时不会出现功值增加。
{"title":"Comparative ab initio study of the electronic structure and thermoelectric properties of tin selenide with electron and hole conductivity","authors":"","doi":"10.1016/j.physb.2024.416529","DOIUrl":"10.1016/j.physb.2024.416529","url":null,"abstract":"<div><div><em>Ab initio</em> calculations of the electronic structure and thermoelectric characteristics of low- and high-temperature phases of tin selenide, SnSe, with electronic and hole conductivity have been performed. It is shown that the calculations of thermoelectric properties on the basis of the Boltzmann-Onzager theory with consideration of carrier scattering on optical phonons lead to results in good agreement with experimental data. At temperatures below 600 K the modeling correctly reproduces the increased values of the figure-of-merit of electron-doped SnSe in comparison with almost stoichiometric or hole-doped selenide calculations. We explain anomalously high figure-of-merit values of the non-doped selenide at T > 600 K by the hole concentration increase due to oxidation of SnSe or the appearance of vacancies in the tin sublattice. For all the considered variants, i.e. for electron-doped low-temperature and high-temperature phases and low-temperature hole-doped phase, the modeling predicts the absence of figure-of-merit increase at exceeding some limiting concentration of current carriers.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-18DOI: 10.1016/j.physb.2024.416554
Titania (TiO2) nanotubular photoelectrodes are a competitive component of titania-based photoelectrochemical water splitting systems. However, TiO2 actively absorbs light in the UV region, which limits its usefulness in solar water splitting, a fast-growing clean energy alternative. In this study, the structural, morphological and optical properties of CuO/TiO2 nanostructures on conductive transparent F-doped SnO2 (FTO) coated glass substrates are engineered for potential application in solar water splitting. The efficacy of a three-step anodization synthesis process to develop free-standing high-fidelity nanotubular TiO2 thin films is demonstrated. CuO nanoblades were deposited on TiO2/FTO by a successive ionic layer adsorption reaction (SILAR). An increase in the precursor concentration and number of immersion cycles influenced the adsorption of CuO and the resultant red shift in the absorption range. SEM and TEM analyses confirm the formation of a heterostructure, with evidence of CuO nanostructures within the TiO2 nanotubular arrays and on the top of the tubes.
{"title":"Structural, morphological, and optical properties of CuO nanoblade-decorated TiO2 nanotubular photoelectrodes","authors":"","doi":"10.1016/j.physb.2024.416554","DOIUrl":"10.1016/j.physb.2024.416554","url":null,"abstract":"<div><p>Titania (TiO<sub>2</sub>) nanotubular photoelectrodes are a competitive component of titania-based photoelectrochemical water splitting systems. However, TiO<sub>2</sub> actively absorbs light in the UV region, which limits its usefulness in solar water splitting, a fast-growing clean energy alternative. In this study, the structural, morphological and optical properties of CuO/TiO<sub>2</sub> nanostructures on conductive transparent F-doped SnO<sub>2</sub> (FTO) coated glass substrates are engineered for potential application in solar water splitting. The efficacy of a three-step anodization synthesis process to develop free-standing high-fidelity nanotubular TiO<sub>2</sub> thin films <span><math><mrow><mo>(</mo><mrow><mo>∼</mo><mn>8</mn><mspace></mspace><mo>μ</mo><mi>m</mi></mrow><mo>)</mo></mrow></math></span> is demonstrated. CuO nanoblades were deposited on TiO<sub>2</sub>/FTO by a successive ionic layer adsorption reaction (SILAR). An increase in the precursor concentration and number of immersion cycles influenced the adsorption of CuO and the resultant red shift in the absorption range. SEM and TEM analyses confirm the formation of a heterostructure, with evidence of CuO nanostructures within the TiO<sub>2</sub> nanotubular arrays and on the top of the tubes.</p></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-18DOI: 10.1016/j.physb.2024.416549
We study Seebeck and Nernst effects in strongly fluctuating superconductors by calculating the Seebeck and Nernst coefficients in the Ginzburg–Landau Lawrence–Doniach model with thermal noise. Strongly thermal fluctuations are represented by the Langevin thermal noise. To capture the interesting fluctuation effects, we use the self-consistent Gaussian approximation to treat cubic term in the equation of motion. Our results including all Landau levels are to treat arbitrary magnetic fields. The Seebeck and Nernst coefficients are calculated for arbitrary temperature and magnetic field. The results are compared to experimental data on Fe-based superconductor FeTe0.6Se0.4 in both the superconducting state below the critical temperature and the normal state above . Our calculation supports the picture of phase disordering of fluctuations above in Fe-based superconductors.
{"title":"Seebeck and Nernst effects in the mixed state of strongly fluctuating superconductors","authors":"","doi":"10.1016/j.physb.2024.416549","DOIUrl":"10.1016/j.physb.2024.416549","url":null,"abstract":"<div><div>We study Seebeck and Nernst effects in strongly fluctuating superconductors by calculating the Seebeck and Nernst coefficients in the Ginzburg–Landau Lawrence–Doniach model with thermal noise. Strongly thermal fluctuations are represented by the Langevin thermal noise. To capture the interesting fluctuation effects, we use the self-consistent Gaussian approximation to treat cubic term in the equation of motion. Our results including all Landau levels are to treat arbitrary magnetic fields. The Seebeck and Nernst coefficients are calculated for arbitrary temperature and magnetic field. The results are compared to experimental data on Fe-based superconductor Fe<span><math><msub><mrow></mrow><mrow><mn>1</mn><mo>+</mo><mi>y</mi></mrow></msub></math></span>Te<sub>0.6</sub>Se<sub>0.4</sub> in both the superconducting state below the critical temperature <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> and the normal state above <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>. Our calculation supports the picture of phase disordering of fluctuations above <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span> in Fe-based superconductors.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-18DOI: 10.1016/j.physb.2024.416555
Tungsten trioxide (WO3) detects UV radiation with great sensitivity while disregarding visible light, and it also has excellent electron mobility, allowing for efficient charge transport and fast response times. This work aims to develop a highly sensitive UV photodetector using WO3 material by optimizing the deposition parameter partial oxygen pressure (PaO2) and annealing the samples at various temperatures to determine the best PaO2 and annealing temperature that results in an improvement in the UV photodetector's sensitivity. The material WO3 was coated on glass substrates using DC magnetron sputtering while altering the PaO2 as 6 × 10−2 Pa, 4 × 10−2 -2 Pa, and 2 × 10−2 Pa, and then each as-deposited sample from varied PaO2 was annealed at temperatures ranging from 100°C to 400°C. When the sample's responses were compared, it was observed that the sample deposited at PaO2 2 × 10−2 Pa and annealed at 400 °C exhibited good photodetection capabilities, as evidenced by several characterization techniques such as SEM, XRD, and IV characterization. The work was subsequently carried out by evaluating the sample deposited at PaO2 2 × 10−2 Pa and annealed at 700 °C, which produced a good result for UV photodetection with the device's responsivity of 1e+4 A/W.
{"title":"Simulation and deposition of Tungsten oxide (WO3) films using DC sputtering towards UV photodetector for high responsivity","authors":"","doi":"10.1016/j.physb.2024.416555","DOIUrl":"10.1016/j.physb.2024.416555","url":null,"abstract":"<div><div>Tungsten trioxide (WO<sub>3</sub>) detects UV radiation with great sensitivity while disregarding visible light, and it also has excellent electron mobility, allowing for efficient charge transport and fast response times. This work aims to develop a highly sensitive UV photodetector using WO<sub>3</sub> material by optimizing the deposition parameter partial oxygen pressure (PaO<sub>2</sub>) and annealing the samples at various temperatures to determine the best PaO<sub>2</sub> and annealing temperature that results in an improvement in the UV photodetector's sensitivity. The material WO<sub>3</sub> was coated on glass substrates using DC magnetron sputtering while altering the PaO<sub>2</sub> as 6 × 10<sup>−2</sup> Pa, 4 × 10<sup>−2</sup> -2 Pa, and 2 × 10<sup>−2</sup> Pa, and then each as-deposited sample from varied PaO<sub>2</sub> was annealed at temperatures ranging from 100°C to 400°C. When the sample's responses were compared, it was observed that the sample deposited at PaO<sub>2</sub> 2 × 10<sup>−2</sup> Pa and annealed at 400 °C exhibited good photodetection capabilities, as evidenced by several characterization techniques such as SEM, XRD, and IV characterization. The work was subsequently carried out by evaluating the sample deposited at PaO<sub>2</sub> 2 × 10<sup>−2</sup> Pa and annealed at 700 °C, which produced a good result for UV photodetection with the device's responsivity of 1e+4 A/W.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-18DOI: 10.1016/j.physb.2024.416552
This article examines electrical properties of fullerene (C70) based all-small-molecule organic photovoltaics with low donor concentration. Enhancements in the properties of devices are observed with the incorporation of lithium fluoride (LiF) and molybdenum trioxide (MoO3) as cathode buffer layers (CBLs). Samples are characterized using field emission-scanning electron microscopy (FESEM), optical absorption spectra, current-voltage (I-V) characteristics in dark and under illumination, and capacitance-frequency (C-ω) measurements. Device with single CBL (LiF) exhibits reduced photoabsorption leading to less saturation photocurrent density (Jsat) and lower maximum exciton generation rate (Gmax), due to non-uniform deposition of LiF in device. In contrast, device having two CBLs (LiF & MoO3) has enhanced the photoabsorption exhibiting high Jsat and Gmax attributed to uniform deposition of MoO3. Moreover, dielectric properties and AC conductivity of devices are also measured confirming the results and these are found to be dependent on the frequency and voltage.
{"title":"Study of electrical properties of fullerene based all-small-molecule low donor organic devices with and without cathode buffer layers for photovoltaic application","authors":"","doi":"10.1016/j.physb.2024.416552","DOIUrl":"10.1016/j.physb.2024.416552","url":null,"abstract":"<div><div>This article examines electrical properties of fullerene (C70) based all-small-molecule organic photovoltaics with low donor concentration. Enhancements in the properties of devices are observed with the incorporation of lithium fluoride (LiF) and molybdenum trioxide (MoO<sub>3</sub>) as cathode buffer layers (CBLs). Samples are characterized using field emission-scanning electron microscopy (FESEM), optical absorption spectra, current-voltage (I-V) characteristics in dark and under illumination, and capacitance-frequency (C-ω) measurements. Device with single CBL (LiF) exhibits reduced photoabsorption leading to less saturation photocurrent density (J<sub>sat</sub>) and lower maximum exciton generation rate (G<sub>max</sub>), due to non-uniform deposition of LiF in device. In contrast, device having two CBLs (LiF & MoO<sub>3</sub>) has enhanced the photoabsorption exhibiting high J<sub>sat</sub> and G<sub>max</sub> attributed to uniform deposition of MoO<sub>3</sub>. Moreover, dielectric properties and AC conductivity of devices are also measured confirming the results and these are found to be dependent on the frequency and voltage.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-17DOI: 10.1016/j.physb.2024.416550
Understanding the structure–property relationship in complex magnetic oxides is crucial for developing new magnetic materials. In this study, we synthesized LaSrFeO Ruddlesden–Popper oxide using spray-pyrolysis method. Electron paramagnetic resonance (EPR) spectra revealed two Fe-associated lines: a broad line indicating short-range antiferromagnetic (AFM) order, disappearing at 375 K, and a narrow line due to the presence of superparamagnetic phase. The magnetic moment from the linewidth’s temperature dependence was A m2. EPR intensity analysis estimated the superparamagnetic to antiferromagnetic phase ratio at 0.014 0.004.
Using density-functional theory with Agapito–Curtarolo–Buongiorno–Nardelli (ACBN0) pseudo-hybrid functional including self-consistent Hubbard correction, we calculated the density of states for two La/Sr atomic distributions. The calculations show that a uniform La/Sr distribution perturbs 2D symmetry of Fe 3 states, which can contribute to the observed lowering of the critical exponent for the magnetically ordered phase. These results highlight the impact of La/Sr distribution on LaSrFeO’s properties.
了解复杂磁性氧化物的结构-性能关系对于开发新型磁性材料至关重要。在这项研究中，我们采用喷雾热解方法合成了 LaSrFeO4 Ruddlesden-Popper 氧化物。电子顺磁共振（EPR）光谱显示了两条与铁有关的线：一条宽线表示短程反铁磁性（AFM）有序，在 375 K 时消失；另一条窄线是由于超顺磁性相的存在。从线宽的温度依赖性得出的磁矩为 10-19 A m2。通过使用 Agapito-Curtarolo-Buongiorno-Nardelli (ACBN0) 伪混合函数（包括自洽 Hubbard U 修正）的密度泛函理论，我们计算了两种 La/Sr 原子分布的状态密度。计算结果表明，均匀的 La/Sr 分布会扰乱铁 3d 态的二维对称性，从而导致观察到的磁有序相临界指数 β 下降。这些结果突显了 La/Sr 分布对 LaSrFeO4 性质的影响。
{"title":"Antiferromagnetism, superparamagnetism, and effects of A-cation distribution on magnetic properties of LaSrFeO4 Ruddlesden–Popper oxides: A combined experimental and theoretical study","authors":"","doi":"10.1016/j.physb.2024.416550","DOIUrl":"10.1016/j.physb.2024.416550","url":null,"abstract":"<div><p>Understanding the structure–property relationship in complex magnetic oxides is crucial for developing new magnetic materials. In this study, we synthesized LaSrFeO<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span> Ruddlesden–Popper oxide using spray-pyrolysis method. Electron paramagnetic resonance (EPR) spectra revealed two Fe-associated lines: a broad line indicating short-range antiferromagnetic (AFM) order, disappearing at 375 K, and a narrow line due to the presence of superparamagnetic phase. The magnetic moment from the linewidth’s temperature dependence was <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>19</mn></mrow></msup></mrow></math></span> A m<sup>2</sup>. EPR intensity analysis estimated the superparamagnetic to antiferromagnetic phase ratio at 0.014 <span><math><mo>±</mo></math></span> 0.004.</p><p>Using density-functional theory with Agapito–Curtarolo–Buongiorno–Nardelli (ACBN0) pseudo-hybrid functional including self-consistent Hubbard <span><math><mi>U</mi></math></span> correction, we calculated the density of states for two La/Sr atomic distributions. The calculations show that a uniform La/Sr distribution perturbs 2D symmetry of Fe 3<span><math><mi>d</mi></math></span> states, which can contribute to the observed lowering of the critical exponent <span><math><mi>β</mi></math></span> for the magnetically ordered phase. These results highlight the impact of La/Sr distribution on LaSrFeO<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span>’s properties.</p></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-16DOI: 10.1016/j.physb.2024.416486
Utilization of micromagnetic simulation is a very attractive subject to understand the magnetic behavior of nanowire arrays that tune their geometrical features and magnetic properties. Here, the micromagnetic simulations utilize to investigation of the single, and a 3 × 3 array of iron nanowires with diameters from 30 to 60 nm. The diameter size and the distance between the wires are selected according to the fabrication of iron nanowires grown in alumina templates. The simulation indicated that an increase in diameter led to a decrease in the coercive field and squareness ratio in both single nanowires and nanowire arrays. Besides, the simulation discloses that the magnetization reversal process of the nanowires with diameters more than 42 nm occurs through the nucleation and propagation of vortex domain walls. In the nanowires array, an increase in wire diameter increases the number of jumps in the hysteresis loop, indicating a more magnetic interaction between the nanowires.
{"title":"The effect of diameter on hysteresis loop squareness in iron nanowires array by micromagnetic simulation","authors":"","doi":"10.1016/j.physb.2024.416486","DOIUrl":"10.1016/j.physb.2024.416486","url":null,"abstract":"<div><p>Utilization of micromagnetic simulation is a very attractive subject to understand the magnetic behavior of nanowire arrays that tune their geometrical features and magnetic properties. Here, the micromagnetic simulations utilize to investigation of the single, and a 3 × 3 array of iron nanowires with diameters from 30 to 60 nm. The diameter size and the distance between the wires are selected according to the fabrication of iron nanowires grown in alumina templates. The simulation indicated that an increase in diameter led to a decrease in the coercive field and squareness ratio in both single nanowires and nanowire arrays. Besides, the simulation discloses that the magnetization reversal process of the nanowires with diameters more than 42 nm occurs through the nucleation and propagation of vortex domain walls. In the nanowires array, an increase in wire diameter increases the number of jumps in the hysteresis loop, indicating a more magnetic interaction between the nanowires.</p></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142240468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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