Pub Date : 2025-01-20DOI: 10.1007/s10948-024-06849-9
K. V. Shilna, K. J. Thomas
Over the last few years, researchers have been seeking novel oxide materials with room-temperature ferromagnetic properties for use in spintronics devices. In a recent work, we have reported room temperature ferromagnetic correlations in BaBiO3 nanoparticles which is non-magnetic in its bulk form. Here we have conducted a systematic study of the magnetic behavior by controlled Pb doping. We observe an increase in magnetic saturation for small Pb doping concentration (~ 1%), this is believed to be due to the strain magnetism induced by doping. Upon further increase in the doping concentration, the ferromagnetic behavior has been found diminished in a controlled manner, which indicates the dominance of non-magnetic ion distribution over strain magnetism.
{"title":"Tuning the Magnetic Behavior of BaBiO3 Nanoparticles by Pb Doping","authors":"K. V. Shilna, K. J. Thomas","doi":"10.1007/s10948-024-06849-9","DOIUrl":"10.1007/s10948-024-06849-9","url":null,"abstract":"<div><p>Over the last few years, researchers have been seeking novel oxide materials with room-temperature ferromagnetic properties for use in spintronics devices. In a recent work, we have reported room temperature ferromagnetic correlations in BaBiO<sub>3</sub> nanoparticles which is non-magnetic in its bulk form. Here we have conducted a systematic study of the magnetic behavior by controlled Pb doping. We observe an increase in magnetic saturation for small Pb doping concentration (~ 1%), this is believed to be due to the strain magnetism induced by doping. Upon further increase in the doping concentration, the ferromagnetic behavior has been found diminished in a controlled manner, which indicates the dominance of non-magnetic ion distribution over strain magnetism.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995251","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 : 2025-01-20DOI: 10.1007/s10948-025-06910-1
Petra Đurkas Grozić, Barbara Keran, Anatoly M. Kadigrobov, Zoran Rukelj, Ivan Kupčić, Danko Radić
We evaluate the Hall coefficient characterising magnetotransport in an intercalated graphite CaC(_6) with the Fermi surface reconstructed by an uniaxial charge density wave from closed pockets to open sheets. As the typical order parameter, corresponding to the pseudo-gap in electronic spectrum and consequently to spacing between electron trajectories in reciprocal space, is of the order of (10^2)K, magnetic breakdown in strong experimentally achievable fields of the order of 10T is inevitable. The classical expressions for the components of the magnetoconductivity tensor are strongly modified by magnetic field-assisted over-gap tunneling causing quantum interference. Due to magnetic breakdown, all magnetoconductivity components undergo strong quantum oscillations reflected in the Hall coefficient. In their nature, these are different than standard Shubnikov de Haas oscillations which would not appear in a system with an open Fermi surface.
{"title":"Hall Coefficient of the Intercalated Graphite CaC(_6) in the Uniaxial CDW Ground State","authors":"Petra Đurkas Grozić, Barbara Keran, Anatoly M. Kadigrobov, Zoran Rukelj, Ivan Kupčić, Danko Radić","doi":"10.1007/s10948-025-06910-1","DOIUrl":"10.1007/s10948-025-06910-1","url":null,"abstract":"<div><p>We evaluate the Hall coefficient characterising magnetotransport in an intercalated graphite CaC<span>(_6)</span> with the Fermi surface reconstructed by an uniaxial charge density wave from closed pockets to open sheets. As the typical order parameter, corresponding to the pseudo-gap in electronic spectrum and consequently to spacing between electron trajectories in reciprocal space, is of the order of <span>(10^2)</span>K, magnetic breakdown in strong experimentally achievable fields of the order of 10T is inevitable. The classical expressions for the components of the magnetoconductivity tensor are strongly modified by magnetic field-assisted over-gap tunneling causing quantum interference. Due to magnetic breakdown, all magnetoconductivity components undergo strong quantum oscillations reflected in the Hall coefficient. In their nature, these are different than standard Shubnikov de Haas oscillations which would not appear in a system with an open Fermi surface.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995326","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 : 2025-01-20DOI: 10.1007/s10948-025-06906-x
Shivakumar Venkataramaiah, Manjula M. Venkatappa, Sujatha M. Hanumegowda, Chikkappa Udagani, Ihab Mohamed Moussa, Eman A. Mahmoud, Devaraja Sannaningaiah
Plant-mediated nanoparticles gaining importance due to their broad spectrum of pharmacological applications in comparison to the synthetic drugs. The nanoparticles amalgamated using plant extracts have been receiving much attention due to the robust phytochemicals and therapeutic potential. Thus, we herein report the biosynthesis and pharmacological evaluation (anti-oxidant, anti-inflammatory, anti-platelet, and anti-cancer properties) of Decalepis hamiltonii leaves extract copper ferrite nanoparticles (DHLE-CuFe2O4 NPs). The characterization of DHLE-CuFe2O4 NPs was carried out using Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy-dispersive X-ray analysis (EDAX), High-resolution transmission electron microscopy (HR-TEM), and Vibrating sample magnetometer (VSM). DHLE-CuFe2O4 NPs exhibited anti-oxidant activity by scavenging 1,1-diphynyl-2-picrylhydrazyl (DPPH) radicals (66.46%) and reduced ferric to ferrous ions at the concentration of 150 μg/mL. Furthermore, DHLE-CuFe2O4 NPs restored the NaNO2-induced oxidative stress markers such as lipid peroxidation, protein carbonyl content, total thiol, and anti-oxidant enzyme (catalase and super oxide dismutase) activities in RBCs. DHLE-CuFe2O4 NPs were non-toxic as it did not cause RBCs lysis, while it exhibited anti-inflammatory activity by inhibiting heat-induced hemolysis, egg albumin, and bovine serum albumin denaturation. In addition, DHLE-CuFe2O4 NPs inhibited ADP and epinephrine-induced platelet aggregation. Most importantly, DHLE-CuFe2O4 NPs showed anti-cancer potential by eliciting cytotoxic effect to MCF-7 cells in a dose-dependent manner. Further, DHLE-CuFe2O4 NPs caused apoptosis to MCF-7 cells which was confirmed by annexin V/PI staining test and flow cytometer. In conclusion, DHLE-CuFe2O4 NPs regulate oxidative stress-induced red blood cell damage, thrombosis, inflammation, and MCF-7 cells growth.
{"title":"A Facile Approach of Synthesizing Biogenic Copper Ferrite Nanoparticles: Characterization, Evaluation of Their Impact on Reducing Oxidative Stress-Induced Pathogenesis, and Human Breast Cancer Proliferation","authors":"Shivakumar Venkataramaiah, Manjula M. Venkatappa, Sujatha M. Hanumegowda, Chikkappa Udagani, Ihab Mohamed Moussa, Eman A. Mahmoud, Devaraja Sannaningaiah","doi":"10.1007/s10948-025-06906-x","DOIUrl":"10.1007/s10948-025-06906-x","url":null,"abstract":"<div><p>Plant-mediated nanoparticles gaining importance due to their broad spectrum of pharmacological applications in comparison to the synthetic drugs. The nanoparticles amalgamated using plant extracts have been receiving much attention due to the robust phytochemicals and therapeutic potential. Thus, we herein report the biosynthesis and pharmacological evaluation (anti-oxidant, anti-inflammatory, anti-platelet, and anti-cancer properties) of <i>Decalepis hamiltonii</i> leaves extract copper ferrite nanoparticles (<i>DHLE-CuFe</i><sub><i>2</i></sub><i>O</i><sub><i>4</i></sub> NPs). The characterization of <i>DHLE-CuFe</i><sub><i>2</i></sub><i>O</i><sub><i>4</i></sub> NPs was carried out using Powder X-ray diffraction (<i>PXRD</i>), Fourier transform infrared spectroscopy (<i>FTIR</i>), Scanning electron microscopy (<i>SEM</i>), Energy-dispersive X-ray analysis (<i>EDAX</i>), High-resolution transmission electron microscopy (<i>HR-TEM</i>), and Vibrating sample magnetometer (<i>VSM</i>). <i>DHLE-CuFe</i><sub><i>2</i></sub><i>O</i><sub><i>4</i></sub> NPs exhibited anti-oxidant activity by scavenging 1,1-diphynyl-2-picrylhydrazyl (DPPH) radicals (66.46%) and reduced ferric to ferrous ions at the concentration of 150 μg/mL. Furthermore, <i>DHLE-CuFe</i><sub><i>2</i></sub><i>O</i><sub><i>4</i></sub> NPs restored the NaNO<sub>2</sub>-induced oxidative stress markers such as lipid peroxidation, protein carbonyl content, total thiol, and anti-oxidant enzyme (catalase and super oxide dismutase) activities in RBCs. <i>DHLE-CuFe</i><sub><i>2</i></sub><i>O</i><sub><i>4</i></sub> NPs were non-toxic as it did not cause RBCs lysis, while it exhibited anti-inflammatory activity by inhibiting heat-induced hemolysis, egg albumin, and bovine serum albumin denaturation. In addition, <i>DHLE-CuFe</i><sub><i>2</i></sub><i>O</i><sub><i>4</i></sub> NPs inhibited ADP and epinephrine-induced platelet aggregation. Most importantly, <i>DHLE-CuFe</i><sub><i>2</i></sub><i>O</i><sub><i>4</i></sub> NPs showed anti-cancer potential by eliciting cytotoxic effect to MCF-7 cells in a dose-dependent manner. Further, <i>DHLE-CuFe</i><sub><i>2</i></sub><i>O</i><sub><i>4</i></sub> NPs caused apoptosis to MCF-7 cells which was confirmed by annexin V/PI staining test and flow cytometer. In conclusion, <i>DHLE-CuFe</i><sub><i>2</i></sub><i>O</i><sub><i>4</i></sub> NPs regulate oxidative stress-induced red blood cell damage, thrombosis, inflammation, and MCF-7 cells growth.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995250","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 : 2025-01-18DOI: 10.1007/s10948-025-06907-w
Valery G. Orlov, Gregory S. Sergeev
Two principal physical properties of La2CuO4 and YBa2Cu3O6 are identified, which can promote the emergence of superconductivity in unconventional high-temperature superconductors. The first property is a specific type of chemical bonding stimulating fluctuations of the charge density. To reveal it, it is necessary to carry out calculations of the electronic band structure and find the parameters of critical points in the charge density distribution in the crystal. For calculation of the electronic band structure of YBa2Cu3O6 the same approach was applied, which we earlier used for the study of the electronic band structure of La2CuO4 and high-temperature superconductors: computer program WIEN2k and exchange potential of Becke and Johnston modified by Tran and Blaha. Such approach allowed us to obtain the antiferromagnetic ground state for the compound YBa2Cu3O6 with a band gap Eg = 1.5 eV and a magnetic moment on copper atoms MCu = 0.71 μB. It turned out that YBa2Cu3O6 compound has a type of chemical bonding similar to that which we found earlier in La2CuO4 and in high-temperature superconductors. Consideration of the symmetry properties of the crystal structures of the La2CuO4 and YBa2Cu3O6 compounds revealed a second characteristic property of them – the existence of magnetic crystal classes that admit a linear magnetoelectric effect. This effect allows the simultaneous existence of local magnetic fields and electric polarization in the sample. Based on two identified characteristic physical properties of the La2CuO4 and YBa2Cu3O6 compounds, a roadmap is proposed for a search of new parent substances for obtaining unconventional high-temperature superconductors.
{"title":"Key Properties of La2CuO4 and YBa2Cu3O6 – Specific Type of Chemical Bonding and Lenear Magnetoelectric Effect, Promoting the Emergence of Superconductivity in Unconventional High-Temperature Superconductors","authors":"Valery G. Orlov, Gregory S. Sergeev","doi":"10.1007/s10948-025-06907-w","DOIUrl":"10.1007/s10948-025-06907-w","url":null,"abstract":"<div><p>Two principal physical properties of La<sub>2</sub>CuO<sub>4</sub> and YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6</sub> are identified, which can promote the emergence of superconductivity in unconventional high-temperature superconductors. The first property is a specific type of chemical bonding stimulating fluctuations of the charge density. To reveal it, it is necessary to carry out calculations of the electronic band structure and find the parameters of critical points in the charge density distribution in the crystal. For calculation of the electronic band structure of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6</sub> the same approach was applied, which we earlier used for the study of the electronic band structure of La<sub>2</sub>CuO<sub>4</sub> and high-temperature superconductors: computer program WIEN2k and exchange potential of Becke and Johnston modified by Tran and Blaha. Such approach allowed us to obtain the antiferromagnetic ground state for the compound YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6</sub> with a band gap <i>E</i><sub>g</sub> = 1.5 eV and a magnetic moment on copper atoms <i>M</i><sub>Cu</sub> = 0.71 <i>μ</i><sub>B</sub>. It turned out that YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6</sub> compound has a type of chemical bonding similar to that which we found earlier in La<sub>2</sub>CuO<sub>4</sub> and in high-temperature superconductors. Consideration of the symmetry properties of the crystal structures of the La<sub>2</sub>CuO<sub>4</sub> and YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6</sub> compounds revealed a second characteristic property of them – the existence of magnetic crystal classes that admit a linear magnetoelectric effect. This effect allows the simultaneous existence of local magnetic fields and electric polarization in the sample. Based on two identified characteristic physical properties of the La<sub>2</sub>CuO<sub>4</sub> and YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6</sub> compounds, a roadmap is proposed for a search of new parent substances for obtaining unconventional high-temperature superconductors.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995150","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 : 2025-01-17DOI: 10.1007/s10948-024-06843-1
Thao Huong Pham
The ({J}_{1}-{J}_{2}) frustrated two-dimensional Ising antiferromagnet in the magnetic fields on the square lattice is studied using a functional integral method. First, we determine possible ground states of the model including Néel antiferromagnetic phase and striped antiferromagnetic phase, which depend on the value of the frustrated parameter (alpha ={J}_{2}/{J}_{1}). The influence of the spin fluctuations in the presence of the frustration, temperature, and longitudinal and transverse fields on these two phases is also studied, which shows the strong impact of the spin fluctuations at the phase transition points. The effects of the longitudinal and transverse fields are highlighted. In addition, we also calculate and plot the temperature dependence of the magnetic susceptibility, and we find a sharp peak related to a phase transition and a rounded peak related to the competition of the effects of the antiferromagnetic exchange couplings, temperature and fields. Hence, we suggest experimental relevance for the given theoretical model with Li2VOSiO4 and YbBi2IO4.
{"title":"Effect of Spin Fluctuation on a Frustrated Two-Dimensional Ising Antiferromagnet in Magnetic Fields","authors":"Thao Huong Pham","doi":"10.1007/s10948-024-06843-1","DOIUrl":"10.1007/s10948-024-06843-1","url":null,"abstract":"<div><p>The <span>({J}_{1}-{J}_{2})</span> frustrated two-dimensional Ising antiferromagnet in the magnetic fields on the square lattice is studied using a functional integral method. First, we determine possible ground states of the model including Néel antiferromagnetic phase and striped antiferromagnetic phase, which depend on the value of the frustrated parameter <span>(alpha ={J}_{2}/{J}_{1})</span>. The influence of the spin fluctuations in the presence of the frustration, temperature, and longitudinal and transverse fields on these two phases is also studied, which shows the strong impact of the spin fluctuations at the phase transition points. The effects of the longitudinal and transverse fields are highlighted. In addition, we also calculate and plot the temperature dependence of the magnetic susceptibility, and we find a sharp peak related to a phase transition and a rounded peak related to the competition of the effects of the antiferromagnetic exchange couplings, temperature and fields. Hence, we suggest experimental relevance for the given theoretical model with Li<sub>2</sub>VOSiO<sub>4</sub> and YbBi<sub>2</sub>IO<sub>4</sub>.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995233","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 : 2025-01-16DOI: 10.1007/s10948-024-06898-0
I. Bensehil, H. Baaziz, T. Ghellab, F. Djeghloul, S. Zaiou, A. Kolli, N. Guechi, Z. Charifi
This study employs first-principles calculations to explore the structural, elastic, electronic, magnetic, and optical properties of the quaternary Heusler compounds CoFeYSb (Y = V, Ti). The structural analysis confirms that both compounds are most stable in the YI configuration. CoFeVSb is found to exhibit ferromagnetic behavior, while CoFeTiSb shows ferrimagnetism. Elastic constants, cohesion energy, and formation energy calculations further validate the stability of the magnetic (I) phase for both materials. Band structure analysis reveals that these compounds are half-metallic, achieving 100% spin polarization at the Fermi level, with spin-down energy gaps of 0.55 eV for CoFeVSb and 0.61 eV for CoFeTiSb. The total magnetic moments comply with the Slater-Pauling 24-electron rule, with values of 3 μB for CoFeVSb and 2 μB for CoFeTiSb. Optical investigations, including the dielectric function, absorption coefficient, and energy loss function, demonstrate strong absorption in the visible and ultraviolet ranges. These results highlight the potential of CoFeYSb compounds for advanced optoelectronic and spintronic applications, offering new opportunities for their integration into electronic and photonic technologies.
{"title":"Investigating the Structural, Electronic, Magnetic, Mechanical, Anisotropic and Optical Aspects of CoFeYSb (Y = V and Ti) Quaternary Heusler Alloys from First Principles","authors":"I. Bensehil, H. Baaziz, T. Ghellab, F. Djeghloul, S. Zaiou, A. Kolli, N. Guechi, Z. Charifi","doi":"10.1007/s10948-024-06898-0","DOIUrl":"10.1007/s10948-024-06898-0","url":null,"abstract":"<div><p>This study employs first-principles calculations to explore the structural, elastic, electronic, magnetic, and optical properties of the quaternary Heusler compounds CoFeYSb (Y = V, Ti). The structural analysis confirms that both compounds are most stable in the YI configuration. CoFeVSb is found to exhibit ferromagnetic behavior, while CoFeTiSb shows ferrimagnetism. Elastic constants, cohesion energy, and formation energy calculations further validate the stability of the magnetic (I) phase for both materials. Band structure analysis reveals that these compounds are half-metallic, achieving 100% spin polarization at the Fermi level, with spin-down energy gaps of 0.55 eV for CoFeVSb and 0.61 eV for CoFeTiSb. The total magnetic moments comply with the Slater-Pauling 24-electron rule, with values of 3 μB for CoFeVSb and 2 μB for CoFeTiSb. Optical investigations, including the dielectric function, absorption coefficient, and energy loss function, demonstrate strong absorption in the visible and ultraviolet ranges. These results highlight the potential of CoFeYSb compounds for advanced optoelectronic and spintronic applications, offering new opportunities for their integration into electronic and photonic technologies.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142994491","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 : 2025-01-15DOI: 10.1007/s10948-024-06862-y
Li Dai, Xianbiao Li, Zhipeng Huang, Shuo Shi
Sc(0,1,2,3 mol%): Ce: Fe: LiNbO3 crystals were grown by conventional Czochralski method. The X-ray diffraction is used to determine lattice constants and analyze the internal structure of crystals. The lattice size was found to increase first and then decrease, and the doping elements do not alter the crystal structure. The concentrations of Sc3+, Ce4+, and Fe3+ ions in the crystals were measured using ICP-AES. With the increase of Sc3+ concentration in the melt, the effective segregation coefficient of Sc3+ was found to decrease, while the effective segregation coefficient of Ce4+ and Fe3+ increased. The birefringence gradient of the ScCeFe-3 sample measured using the birefringence gradient method was 3.3 × 10−5 ∆R/cm−1, which was the best optical homogeneity.
{"title":"Investigation of Defect Structure and Optical Properties of Sc(0,1,2,3 mol%): Ce: Fe: LiNbO3 Crystals","authors":"Li Dai, Xianbiao Li, Zhipeng Huang, Shuo Shi","doi":"10.1007/s10948-024-06862-y","DOIUrl":"10.1007/s10948-024-06862-y","url":null,"abstract":"<div><p>Sc(0,1,2,3 mol%): Ce: Fe: LiNbO<sub>3</sub> crystals were grown by conventional Czochralski method. The X-ray diffraction is used to determine lattice constants and analyze the internal structure of crystals. The lattice size was found to increase first and then decrease, and the doping elements do not alter the crystal structure. The concentrations of Sc<sup>3+</sup>, Ce<sup>4+</sup>, and Fe<sup>3+</sup> ions in the crystals were measured using ICP-AES. With the increase of Sc<sup>3+</sup> concentration in the melt, the effective segregation coefficient of Sc<sup>3+</sup> was found to decrease, while the effective segregation coefficient of Ce<sup>4+</sup> and Fe<sup>3+</sup> increased. The birefringence gradient of the ScCeFe-3 sample measured using the birefringence gradient method was 3.3 × 10<sup>−5</sup> ∆R/cm<sup>−1</sup>, which was the best optical homogeneity.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142994410","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 : 2025-01-15DOI: 10.1007/s10948-025-06900-3
T. Dadiani, T. Tchabukiani, D. Jishiashvili, D. Daraselia, D. Japaridze, F. La Mattina, A. Shengelaya
The transport and magnetic properties of the Magnéli phase tungsten oxide WO2.90, prepared via spark plasma sintering, were investigated across a broad temperature range of 4–550 K, including the previously unexplored low-temperature region below 300 K. Microstructure analysis shows that obtained pellets are fully dense, enabling reliable measurement of transport properties. Resistivity measurements reveal typical metallic behavior of WO2.90 at low temperatures. Above room temperature, resistivity tends to saturate by reaching a maximum value near 430 K. The resistivity saturation indicates that Mott-Ioffe-Regel limit is approached, where the charge carrier mean free path becomes comparable to the interatomic spacing. The temperature dependence of the resistivity can be well described by the phenomenological parallel resistor model. Significant positive magnetoresistance was observed at low temperatures, with an unusual linear dependence on the magnetic field. Despite its metallic conductivity, WO2.90 displays weak diamagnetism, likely due to the substantial core diamagnetism of tungsten and the bipolaronic pairing of charge carriers.
{"title":"Transport and Magnetic Properties of Magnéli Phase Tungsten Oxide WO2.90 Prepared by Spark Plasma Sintering","authors":"T. Dadiani, T. Tchabukiani, D. Jishiashvili, D. Daraselia, D. Japaridze, F. La Mattina, A. Shengelaya","doi":"10.1007/s10948-025-06900-3","DOIUrl":"10.1007/s10948-025-06900-3","url":null,"abstract":"<div><p>The transport and magnetic properties of the Magnéli phase tungsten oxide WO<sub>2.90</sub>, prepared via spark plasma sintering, were investigated across a broad temperature range of 4–550 K, including the previously unexplored low-temperature region below 300 K. Microstructure analysis shows that obtained pellets are fully dense, enabling reliable measurement of transport properties. Resistivity measurements reveal typical metallic behavior of WO<sub>2.90</sub> at low temperatures. Above room temperature, resistivity tends to saturate by reaching a maximum value near 430 K. The resistivity saturation indicates that Mott-Ioffe-Regel limit is approached, where the charge carrier mean free path becomes comparable to the interatomic spacing. The temperature dependence of the resistivity can be well described by the phenomenological parallel resistor model. Significant positive magnetoresistance was observed at low temperatures, with an unusual linear dependence on the magnetic field. Despite its metallic conductivity, WO<sub>2.90</sub> displays weak diamagnetism, likely due to the substantial core diamagnetism of tungsten and the bipolaronic pairing of charge carriers.\u0000</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142994408","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 : 2025-01-15DOI: 10.1007/s10948-025-06903-0
Izumi Hase
In electronic models on lattices with strong geometric frustration (flat band models), the band dispersion of electrons can vanish, resulting in what is known as a flat band. Flat bands are known to serve as a platform for the emergence of various intriguing physical properties. Realizing flat bands in actual materials, however, remains a challenging task. In this paper, we report that the flat band model approximately holds in the pyrochlore oxide Pb(_2)Bi(_2)O(_7), as demonstrated by first-principles calculations. Furthermore, we propose that, among the two key parameters in flat band systems—the flat band width and the carrier density—the latter can be selectively controlled, approximately, by utilizing the solid solution Pb(_2)(Sb,Bi)(_2)O(_7). This finding represents a new step toward “flatronics,” a field focused on controlling flat band systems.
在具有强几何挫折的晶格上的电子模型(平带模型)中,电子的能带色散会消失,导致所谓的平带。众所周知,平带是各种有趣的物理性质出现的平台。然而,在实际材料中实现平带仍然是一项具有挑战性的任务。在本文中,我们报告了平带模型在氧化焦绿盐Pb (_2) Bi (_2) O (_7)中近似成立,正如第一线原理计算所证明的那样。此外,我们提出,在平带系统的两个关键参数——平带宽度和载流子密度中,后者可以通过利用固溶体Pb (_2) (Sb,Bi) (_2) O (_7)有选择性地进行近似控制。这一发现代表了迈向“平面电子学”的新一步,“平面电子学”是一个专注于控制平面带系统的领域。
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Pub Date : 2025-01-14DOI: 10.1007/s10948-024-06850-2
Bassam M. Mustafa
<div><p>About four decades elapsed since the discovery of La<sub>2-x</sub>Sr<sub>x</sub>CuO<sub>4</sub> (LSCO) and still no consensus on a theoretical model to describe the phase diagram of the high-Tc cuprates, including the HTSC mechanism itself. What is new in the current treatment of research is that it may introduce a new vision for superconductive behavior in La<sub>2-x</sub>Sr<sub>x</sub> CuO<sub>4</sub>. This vision is based on considering aspects which were not given the needed attention. These are (1) crystal symmetry affects Sr<sup>2+</sup>dopants distribution on lattice sites and (2) Sr<sup>2+</sup> dopants affect lattice symmetry and superconductivity, whereas all solutions are given concentrate on charge carriers but till now no conscience on it. So, using the basic aspects of the new vision, this research may succeed to a good extent to uncover and determine the role of symmetric distribution of dopants in the appearance of many anomalies like charge strips and its turnover, and of complex behavior of phases in the face diagram. So, I build models to explain experimental facts depending on symmetry aspects. The study reveals also the role of doping in superconductivity, and I think, it was successful to some extent. By analytical treatment of the distances between dopants on the lattice site in the charged strips near the point of start of superconductivity, it was found that the distances between dopants are within the coherence length (C.L <sub>dopant</sub>. = 35.35 Å) knowing that (C.L <sub>real</sub> = 33 Å) is the distant within which superconductivity changes. It means that the symmetric distribution of dopants affects superconductivity. Doping with Sr<sup>2+</sup> leads to a change in the lattice symmetry from tetragonal to orthorhombic, analytical model was used in this research to prove the experimental facts about these changes, it was found that this symmetry change leads to the collapse of the lattice in the space around Sr<sup>2+</sup> as in Fig. 3, and this collapsed can be considered equivalent to a negative charge at the center of this space. Based on the symmetric effects on dopant distribution, a model for the phase diagram can be applied easily to give explanations of the unclear changes in the phase diagram on a single scenario depending on the distribution of (1 or 2 or 3) Sr ions for all the lattice sites; this doping steps of the Sr<sup>2+</sup> which are proportional to the increase in concentration can clearly explain the strange formation of the different phases in the LSCO phase diagram. Consistent with the new vision in this research on superconductivity in LSCO, a model is suggested for hole pairing, in which the O<sup>2−</sup> atom in the CuO plane that is nearer to Sr<sup>2+</sup> is the site around which hole pairing happens as in Fig. 5. The Coulombic repulsion between holes is zero due to the opposite directions of attraction forces with the O<sup>2−</sup> ion and provides a place for superexchange
{"title":"The Effect of Sr Substitution on the Crystal Symmetry and Superconductivity of the High-temperature Superconductor La 2-x Sr x CuO4","authors":"Bassam M. Mustafa","doi":"10.1007/s10948-024-06850-2","DOIUrl":"10.1007/s10948-024-06850-2","url":null,"abstract":"<div><p>About four decades elapsed since the discovery of La<sub>2-x</sub>Sr<sub>x</sub>CuO<sub>4</sub> (LSCO) and still no consensus on a theoretical model to describe the phase diagram of the high-Tc cuprates, including the HTSC mechanism itself. What is new in the current treatment of research is that it may introduce a new vision for superconductive behavior in La<sub>2-x</sub>Sr<sub>x</sub> CuO<sub>4</sub>. This vision is based on considering aspects which were not given the needed attention. These are (1) crystal symmetry affects Sr<sup>2+</sup>dopants distribution on lattice sites and (2) Sr<sup>2+</sup> dopants affect lattice symmetry and superconductivity, whereas all solutions are given concentrate on charge carriers but till now no conscience on it. So, using the basic aspects of the new vision, this research may succeed to a good extent to uncover and determine the role of symmetric distribution of dopants in the appearance of many anomalies like charge strips and its turnover, and of complex behavior of phases in the face diagram. So, I build models to explain experimental facts depending on symmetry aspects. The study reveals also the role of doping in superconductivity, and I think, it was successful to some extent. By analytical treatment of the distances between dopants on the lattice site in the charged strips near the point of start of superconductivity, it was found that the distances between dopants are within the coherence length (C.L <sub>dopant</sub>. = 35.35 Å) knowing that (C.L <sub>real</sub> = 33 Å) is the distant within which superconductivity changes. It means that the symmetric distribution of dopants affects superconductivity. Doping with Sr<sup>2+</sup> leads to a change in the lattice symmetry from tetragonal to orthorhombic, analytical model was used in this research to prove the experimental facts about these changes, it was found that this symmetry change leads to the collapse of the lattice in the space around Sr<sup>2+</sup> as in Fig. 3, and this collapsed can be considered equivalent to a negative charge at the center of this space. Based on the symmetric effects on dopant distribution, a model for the phase diagram can be applied easily to give explanations of the unclear changes in the phase diagram on a single scenario depending on the distribution of (1 or 2 or 3) Sr ions for all the lattice sites; this doping steps of the Sr<sup>2+</sup> which are proportional to the increase in concentration can clearly explain the strange formation of the different phases in the LSCO phase diagram. Consistent with the new vision in this research on superconductivity in LSCO, a model is suggested for hole pairing, in which the O<sup>2−</sup> atom in the CuO plane that is nearer to Sr<sup>2+</sup> is the site around which hole pairing happens as in Fig. 5. The Coulombic repulsion between holes is zero due to the opposite directions of attraction forces with the O<sup>2−</sup> ion and provides a place for superexchange","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142976576","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}