| 1. |
- Fellström, Bengt, 1947-, et al.
(författare)
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Associations Between Apolipoprotein A1, High-Density Lipoprotein Cholesterol, and Urinary Cytokine Levels in Elderly Males and Females
- 2019
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Ingår i: Journal of Interferon and Cytokine Research. - : Mary Ann Liebert Inc. - 1079-9907 .- 1557-7465. ; 40:2, s. 71-74
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Tidskriftsartikel (refereegranskat)abstract
- There exists a close relationship between cardiovascular diseases and chronic kidney disease. Apolipoprotein A1 and high-density lipoprotein (HDL) cholesterol are widely used as cardiovascular risk markers but they also have anti-inflammatory properties. The aim of this study was to investigate any associations between HDL levels and cytokine levels in urine. We randomly selected 90 urine samples from the Prospective Investigation of the Vasculature in Uppsala Seniors Study (41 males and 49 females). The samples were analyzed with 2 multiplex assays, Multiplex Inflammation I and Cardiovascular II kits (Olink Bioscience, Uppsala, Sweden). We analyzed the correlations between 158 cytokines in urine with apolipoprotein A1, HDL cholesterol, apolipoprotein B, and low-density lipoprotein cholesterol. There were strong correlations for apolipoprotein A1 and HDL cholesterol with individual cytokines. After adjustment for multiplicity testing, there were 33 significant correlations between apolipoprotein A1 and cytokine levels and 14 of these were also significantly correlated with HDL cholesterol. The strongest associations were observed for IL-1α, SPON2, RAGE, PAR-1, TRAIL-R2, IL-4RA, TNFRSF11A, and SCF. A total of 28 out of 33 correlations were negative, indicating a negative relationship between apolipoprotein A1 and urinary cytokines. The study shows a negative correlation between apolipoprotein A1 and HDL cholesterol and urinary cytokine levels. The finding is in agreement with the anti-inflammatory properties of HDL.
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| 2. |
- Begum, Afroza, et al.
(författare)
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Prevalence of suicide ideation among adolescents and young adults in Bangladesh
- 2017
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Ingår i: International Journal of Mental Health. - : Informa UK Limited. - 0020-7411 .- 1557-9328. ; 46:3, s. 177-187
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Tidskriftsartikel (refereegranskat)abstract
- Suicide is a leading cause of death world-wide. However, adolescent suicidal behavior is a neglected public health issue, especially in low-income countries such as Bangladesh. The study was conducted to estimate the prevalence of suicidal ideation among adolescents in a rural community and to examine factors associated with suicidal ideation. A cross-sectional survey was carried out in 2013 among 2,476 adolescents aged 14–19 years, selected randomly from a rural community of Bangladesh. An adapted version of the WHO/SUPRE-MISS questionnaire was used to collect data in the Raiganj sub-district. A two stage screening was performed to identify the suicidal ideation cases. It was found that the life-time prevalence for suicidal ideation was 5 percent among adolescents. The majority of the adolescents with suicidal ideation were females 66 (52.8%), unmarried 103 (82.4%), and students 92 (73%). Suicidal ideation was statistically significantly associated with age, education, occupation, living with parents or others, and house ownership. Respondents who were aged 18–19 years, had secondary school certificate (SSC) and secondary school certificate (HSC) or higher education, were day laborers, had own house, and do not lived with parents had odds ratios of 2.31 (CI 1.46–3.65), 2.38 (CI 1.51–3.77), 4.15 (CI 2.41–7.14), 0.28 (CI 0.13–0.60), 0.14(CI 0.05–0.35), and 1.80 (CI 1.07–3.03), respectively. Among adolescents, the prevalence of life-time suicidal ideation was moderately high. Age, education, occupation, house ownership, and living with parents were statistically significantly associated with suicidal ideation. It is important to design and implement effective community based suicide prevention programs for adolescents in Bangladesh.
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| 3. |
- Cha, Eunjung, 1985, et al.
(författare)
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Two-Finger InP HEMT Design for Stable Cryogenic Operation of Ultra-Low-Noise Ka- and Q-Band LNAs
- 2017
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 65:12, s. 5171-5180
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the cryogenic stability of two-finger 100-nm gate-length InP HEMTs aimed for Ka- and Q-band ultra-low noise amplifiers (LNAs). InP HEMTs with unit gate widths ranging between 30 and 50 mu m exhibit unstable cryogenic behavior with jumps in drain current and discontinuous peaks in transconductance. We also find that shorter gate length enhances the cryogenic instability. We demonstrate that the instability of two-finger transistors can be suppressed by either adding a source air bridge, connecting the back end of gates, or increasing the gate resistance. A three-stage 24-40 GHz and a four-stage 28-52-GHz monolithic microwave-integrated circuit LNA using the stabilized InP HEMTs are presented. The Ka-band amplifier achieves a minimum noise temperature of 7 K at 25.6 GHz with an average noise temperature of 10.6 K at an ambient temperature of 5.5 K. The amplifier gain is 29 dB +/- 0.6 dB. The Q-band amplifier exhibits minimum noise temperature of 6.7 K at 32.8 GHz with average noise temperature of 10 K at ambient temperature of 5.5 K. The amplifier gain is 34 dB +/- 0.8 dB. To our knowledge, the Ka- and Q-band amplifiers demonstrate the lowest noise temperature reported so far for InP cryogenic LNAs.
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| 4. |
- Eriksson, Janna, 1992, et al.
(författare)
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The effects of iron and selenium in iodine containing multivitamins on thyroid related compounds during pregnancy in Sweden: a randomized placebo cotrolled trial
- 2017
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Ingår i: 87th Annual Meeting of the American Thyroid Association. Thyroid, 27(S1), poster 71. - : Mary Ann Liebert Inc. - 1050-7256 .- 1557-9077.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Multivitamins with iodine are advocated to pregnant women to avoid iodine deficiency, as iodine may be beneficial for brain development in the child. Multivitamins also contain iron and selenium that may affect thyroid hormone metabolism. Iron is included in the tyreoperoxidase enzyme promoting the coupling of iodine to thyroglobulin (Tg) and selenium is incorporated in deiodinases that regulates levels of thyroxine (T4) and triiodothyronine (T3). There is no previous studies on the effects of iodine containing multivitamins on iron and selenium levels in pregnant women and the relation to thyroid hormone levels. This was a randomized, double-blinded controlled trial of 200 pregnant women, who were randomized to multivitamins containing 150 lg iodine, 12 mg iron and 50 lg selenium/day or multivitamins without iodine, iron and selenium in pregnancy week 7–12 until delivery, besides iron supplements on usual routines. Thyroid hormones, Tg, selenium (ref 0.7– 1.2 lmol/L) and iron measurements (ferritin (ref 15–150 mg/L), transferrin saturation (ref 0.1–0.5)) were collected in the third trimester. Urinary iodine concentration confirmed mild ID in the control group with a Tg increase. In the third trimester, 139 patients were left for sampling. In the active group (n = 67) median (interquartile range (IQR)) selenium levels were 0.72 (0.16) vs 0.61 (0.14) in the control group (n = 72), p < 0.001. Low selenium values were noted in 70.0% of participants and it was more common in the control group (81.9%), p < 0.001. Median (IQR) Tg levels was higher in those with low selenium 30.0 (30.5) than in those with normal selenium 20.5 (21.5), p = 0.037. Thyroid hormones did not differ between active/control groups or low/normal selenium groups, but FT3/FT4 ratio was higher in the low selenium group than in the normal selenium group (0.35 (0.08) vs 0.33 (0.08)), p= 0.025. Ferritin in the active group was 22.0 (21.0) and 20.0 (21.5) in the control group, p = 0.393 and transferrin saturation 0.20 (0.11) and 0.18 (0.18), p = 0.802, respectively. Multivitamins used during pregnancy to increase iodine levels also increase selenium levels where effects on thyroid metabolism needs further evaluation.
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| 5. |
- Kaczmarski, J., et al.
(författare)
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Transparent Ru–Si–O/In–Ga–Zn–O MESFETs on flexible polymer substrates
- 2018
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Ingår i: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 65:1, s. 129-135
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Tidskriftsartikel (refereegranskat)abstract
- With the development of novel device applications, e.g., in the field of Internet of Things or point-of-care personalized diagnostic systems, came an increased demand for MESFETs for fast and low-power consumption integrated circuits and active-matrix displays. In this paper, we present fabrication and characterization of transparent Ru–Si–O/In–Ga–Zn–O MESFETs on flexible substrates. The use of transparent conducting oxide, namely, Ru–Si–O, as Schottky gate electrode, allows for processing the devices at room temperature, enabling the utilization of such low-temperature substrates as polyethylene terephthalate foil and paper. It was shown that tuning the device geometry allows realization of transistors providing on-current up to 2 mA, while the highest on-to-off current ratio equals 2 × 105, with off-current below 1 nA, carrier mobility in the channel exceeds 9 cm2·V−1·s−1, and subthreshold swing is below 250 mV·decade−1
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| 6. |
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| 7. |
- Baykal, A., et al.
(författare)
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Synthesis, Characterization, and Dielectric Properties of BaFe10(Mn2+Zn2+Zn2+)O-19 Hexaferrite
- 2016
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer. - 1557-1939 .- 1557-1947. ; 29:1, s. 199-205
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Tidskriftsartikel (refereegranskat)abstract
- Barium hexaferrite with nominal chemical composition BaMnZn2Fe10O19 has been synthesized by sol-gel method, using polymethyl methacrylate (PMMA) as a template. Fourier transform infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRD) were used for approving the formation of barium hexaferrites. In addition, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were performed to investigate the structural and morphological properties of BaM. The dielectric properties were studied by impedance measurements as a function of frequency (in the range 0.1 Hz-1 MHz). The XRD patterns confirmed the formation of single-phase magnetoplumbite with crystallite size around 73 nm. The results of dielectric parameters and conductivity measurements showed three regions with different behaviors in electrical conduction mechanism.
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| 8. |
- Benhouria, Y., et al.
(författare)
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Dynamic Magnetic Properties of a Mixed Spin Ising Double-Walled Ferromagnetic Nanotubes : A Dynamic Monte Carlo Study
- 2017
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 30:3, s. 839-844
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Tidskriftsartikel (refereegranskat)abstract
- Using the dynamic Monte Carlo simulation, the dynamic critical temperature of a ferromagnetic or ferrimagnetic double-walled nanotubes (DWNTs) is studied within the kinetic Ising model under the presence of a time-dependent oscillating external magnetic and crystal fields with mixed spins S (A) = 1 and S (B) = 3/2. The effects of the time-dependent oscillating external magnetic field, the period of the oscillating magnetic field, and the crystal field on the thermal behavior of the dynamic sub-lattice order parameters and the total dynamic order parameter, total dynamical magnetic susceptibility, dynamical specific heat, and dynamic hysteresis of a DWNTs are studied. Our theoretical predictions may be a reference for future experiment studies of the nanostructures.
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| 9. |
- Bouhou, S., et al.
(författare)
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Magnetic Properties of a Transverse Ising Nanoparticle
- 2015
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 28:3, s. 885-890
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Tidskriftsartikel (refereegranskat)abstract
- We use the effective field theory with a probability distribution technique to investigate the magnetic properties of an antiferromagnetic Ising core/shell nanoparticle with a negative interlayer coupling core/shell in the presence of both the longitudinal and the transverse fields. Nearest-neighbor pair interactions are incorporated between the Ising spins in three parts that are core, core/shell, and surface shell. The effects of the external and the transverse fields and the exchange interactions between core/shell and in surface shell on the hysteresis loops and the susceptibility of the nanoparticle are examined. A number of interesting phenomena have been found.
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| 10. |
- de Andrés Prada, Roberto, et al.
(författare)
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Growth and Nanofabrication of All-Perovskite Superconducting/Ferromagnetic/Superconducting Junctions
- 2019
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 32:9, s. 2721-2726
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Tidskriftsartikel (refereegranskat)abstract
- We fabricate and study experimentally all-perovskite-oxide superconductor/ferromagnetic insulator/superconductor (S/FI/S) tunnel junctions made out of the high-temperature cuprate superconductor YBa2Cu3O7−y (YBCO) and the colossal magnetoresistive manganite LaMnO3 (LMO) in the ferromagnetic insulator state. YBCO/LMO/YBCO heterostructures with different LMO thicknesses (5, 10, and 20 nm) are grown epitaxially via pulsed laser deposition. Nanoscale S/FI/S junctions with sizes down to 300 nm are made by three-dimensional nano-sculpturing with focused ion beam. Junctions with a thick (20 nm) LMO barrier exhibit a large negative magnetoresistance below TCurie∼160 K, typical for colossal magnetoresistive manganites, as well as a kink in the current-voltage characteristics at large bias (V∼1–2 Volts), attributed to Zener-type tunneling. However, they do not show a measurable Josephson current. On the contrary, junctions with the thinnest 5-nm LMO barrier exhibit a large supercurrent and no signs of magnetism. The latter may indicate the presence of pinholes due to thickness inhomogeneity and/or a ∼ 2 nm dead magnetic layer at the YBCO / LMO interface caused, e.g., by interdiffusion or strain. The junction with an intermediate 10-nm LMO barrier exhibited a desired S/FI/S junction behavior with significant negative magnetoresistance and signatures of a small Josephson current.
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| 11. |
- Edge, Jonathan M., et al.
(författare)
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Upper Critical Field as a Probe for Multiband Superconductivity in Bulk and Interfacial STO
- 2015
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 28:8, s. 2373-2384
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the temperature dependence of the upper critical field H-c2 as a tool to probe the possible presence of multiband superconductivity at the interface between LaAlO3 and SrTiO3 (LAO/STO). The behaviour of H-c2 can clearly indicate two-band superconductivity through its nontrivial temperature dependence. For the disorder scattering dominated two-dimensional LAO/STO interface, we find a characteristic non-monotonic curvature of the H-c2(T). We also analyse the H-c2 for multiband bulk STO and find similar behaviour.
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| 12. |
- El Hamri, M., et al.
(författare)
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Thermodynamic Properties of the Core/Shell Antiferromagnetic Ising Nanocube
- 2015
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 28:10, s. 3127-3133
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Tidskriftsartikel (refereegranskat)abstract
- Using the effective field theory with correlations, the effects of the exchange interaction on the thermal behaviors of the total magnetization, internal energy, specific heat, entropy, and free energy of a transverse antiferromagnetic Ising nanocube are investigated. The phase diagram is also calculated and discussed in detail.
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| 13. |
- Htoutou, K., et al.
(författare)
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The Magnetic Properties of the Mixed Ferrimagnetic Ising System with Random Crystal Field
- 2017
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : SPRINGER. - 1557-1939 .- 1557-1947. ; 30:5, s. 1247-1256
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Tidskriftsartikel (refereegranskat)abstract
- Using the effective-field theory EFT based on the probability distribution technique, the effect of the random crystal field on the magnetic properties of ferrimagnetic mixed Ising system with both spin-1 and spin-3/2 is investigated. The critical temperature is discussed as function of different strengths of the random crystal field and the exchange interactions. The phase diagrams are calculated numerically for a square lattice and the number of characteristic phenomena, such as the tricritical point are found. Our results are different to that reported in Souza et al. (Physica A 444, 589-600 2016).
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| 14. |
- Jouault, B., et al.
(författare)
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Josephson Coupling in Junctions Made of Monolayer Graphene Grown on SiC
- 2016
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1947 .- 1557-1939. ; 29:5, s. 1145-1150
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Tidskriftsartikel (refereegranskat)abstract
- Chemical vapor deposition has proved to be successful in producing graphene samples on silicon carbide (SiC) homogeneous at the centimeter scale in terms of Hall conductance quantization. Here, we report on the realization of co-planar diffusive Al/ monolayer graphene/ Al junctions on the same graphene sheet, with separations between the electrodes down to 200 nm. Robust Josephson coupling has been measured for separations not larger than 300 nm. Transport properties are reproducible on different junctions and indicate that graphene on SiC substrates is a concrete candidate to provide scalability of hybrid Josephson graphene/superconductor devices.
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| 15. |
- Kagan, Maxim Yu., et al.
(författare)
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High-T (c) and Low-T (c) Superconductivity in Electron Systems with Repulsion
- 2016
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 29:4, s. 1043-1048
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the instability of the normal state of purely repulsive fermionic systems towards the transition to the Kohn-Luttinger superconducting state. We construct the superconducting phase diagrams of these systems in the framework of the Hubbard and Shubin-Vonsovsky models on the square and hexagonal lattices. We show that an account for the long-range Coulomb interactions, as well as the Kohn- Luttinger renormalizations, lead to an increase in the critical superconducting temperatures in various materials, such as high-temperature superconductors, idealized monolayer, and bilayer of doped graphene. Additionally, we discuss the role of the structural disorder and the nonmagnetic impurities in superconducting properties of real graphene systems.
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| 16. |
- Larsson, Sven, 1941
(författare)
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Conductivity in Cuprates Arises from Two Different Sources: One-Electron Exchange and Disproportionation
- 2017
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1947 .- 1557-1939. ; 30:2, s. 275-285
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Tidskriftsartikel (refereegranskat)abstract
- Simulation of the resistivity in the normal state of doped La2-x Sr (x) CuO4 has been performed using a hopping model based on Marcus theory. The results are in substantial agreement with experimental results. At oxidative doping, Cu(III) sites are formed and electron mobility possible due to hopping: Cu(III)Cu(II) -> Cu(II)Cu(III) (one-electron exchange). In the underdoped, non-metallic region, the resistivity (rho) decreases from almost insulation at T = 0 to a minimum at about T = 100 K. rho then increases more than linearly with T (similar to T (3/2)) in the region 100 Cu(I) + Cu(III) is responsible for the strong absorption in the visible spectrum of La2CuO4. The down-shift of spectral density with doping (x) in La2-x Sr (x) CuO4 depends on the appearance of Cu(III) sites which makes optical as well as thermal one-electron exchange transitions possible with lower energy. Disproportionation occurs spontaneously for x > 0.06, opening up for electron pair formation. Configuration interaction between two-electron states of low chemical potential, but strong vibrational coupling, gives rise to the superconductor and pseudogaps. Data from photo-induced conductivity and absorption spectra are used in the simulation, which gives results in good agreement with experiments. Possible explanations for Raman and MIR absorption suggest themselves.
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| 17. |
- Larsson, Sven, 1941
(författare)
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Effect of Pressure on Superconducting Properties
- 2015
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1947 .- 1557-1939. ; 28:6, s. 1693-1698
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that the existence of superconductivity in a material, and its critical temperature, depends strongly on pressure. Several parameters are pressure-dependent: (1) structure, particularly bond distances, (2) Hubbard U, (3) coupling between sites, and (4) orbital occupation number. Eliashberg theory often leads to incorrect predictions, for example in A(3)C(60) with A = K, Rb, and Cs. While T (C) is correctly predicted to be higher for Rb3C60 than for K3C60 and decreasing with pressure in both cases, Cs3C60 is not superconducting at ambient pressure. The same is the case for pure metals such as Cs and Ca (superconducting at high pressure). A theory for electron pairs, similar to the Marcus model for single electrons, appears to agree with the experiment in most cases.
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| 18. |
- Larsson, Sven, 1941
(författare)
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Resistivity in Cuprates and the Pseudogap
- 2017
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1947 .- 1557-1939. ; 30:3, s. 777-782
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Tidskriftsartikel (refereegranskat)abstract
- The temperature dependence of resistivity (rho) in the normal state of La2-x Sr (x) CuO4 is calculated from electron transfer (ET) rates. The minimum at about 100 K for doping levels less than 6 % is characteristic for all cuprates. The resistivity depends on ET between Cu(III) and Cu(II) sites. For T 100 K depends on increased kinetic energy in a Landau avoided crossing. The agreement with experimental data is convincing. The behaviour for T -> 0 can be explained as nuclear tunnelling. For T > 400 K, rho bends down, presumably because the pseudogap is overcome at a higher kinetic energy.
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| 19. |
- Larsson, Sven, 1941
(författare)
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T-C Dependence on Hubbard U in the Fullerenes
- 2015
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1947 .- 1557-1939. ; 28:2, s. 315-317
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Tidskriftsartikel (refereegranskat)abstract
- Pair formation occurs when the free energy for charge disproportionation is negative, i.e., U 0 is the difference between ionization energy and electron affinity, and R is the distance between the lattice sites. -1/R (atomic units) is the particle-hole attraction after charge separation in the case of two C-60 ions, the much needed negative term. In the case of alkali C-60 salts of type A(3)C(60), the attractive term 1 /R is the smallest for the largest ion A(+), i.e., Cs+. Hence, U is increasing with the lattice constant R, i.e., with the size of the alkali ion. Lack of superconductivity in Cs3C60 can be interpreted as U > 0 for this salt, while U 4 kbar.
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| 20. |
- Levchenko, K., et al.
(författare)
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Novel Quaternary Dilute Magnetic Semiconductor (Ga,Mn)(Bi,As) : Magnetic and Magneto-Transport Investigations
- 2017
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 30:3, s. 825-829
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic and magneto-transport properties of thin layers of the (Ga,Mn)(Bi,As) quaternary dilute magnetic semiconductor grown by the low-temperature molecular-beam epitaxy technique on GaAs substrates have been investigated. Ferromagnetic Curie temperature and magneto-crystalline anisotropy of the layers have been examined by using magneto-optical Kerr effect magnetometry and low-temperature magneto-transport measurements. Post-growth annealing treatment of the layers has been shown to enhance the hole concentration and Curie temperature in the layers. A significant increase in the magnitude of magneto-transport effects caused by incorporation of a small amount of Bi into the (Ga,Mn)As layers, revealed in the planar Hall effect (PHE) measurements, is interpreted as a result of enhanced spin-orbit coupling in the (Ga,Mn)(Bi,As) layers. A two-state behaviour of the planar Hall resistance at zero magnetic field provides its usefulness for applications in non-volatile memory devices.
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| 21. |
- Massarotti, D., et al.
(författare)
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Hysteretic Critical State in Coplanar Josephson Junction with Monolayer Graphene Barrier
- 2017
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1947 .- 1557-1939. ; 30:1, s. 5-14
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Tidskriftsartikel (refereegranskat)abstract
- Coplanar Al/graphene/Al junctions fabricated on the same graphene sheet deposited on silicon carbide (SiC), show robust Josephson coupling at subKelvin temperature, when the separations between the electrodes is below 400 nm. Remarkably, a hysteretic Critical State sets in when ramping an orthogonal magnetic field, with a sudden collapse of the Josephson critical current I (c) when turning the field on, and a revival of I (c) when inverting the sweep. Similar hysteresis can be found in granular superconducting films which may undergo the Berezinskii-Kosterlitz-Thouless transition. Here, we give quantitative arguments to prove that this odd behavior of the magnetoconductance gives evidence for an incipient Berezinskii-Kosterlitz-Thouless transition with drift and pinning of fluctuating free vortices induced by the current bias.
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| 22. |
- Ord, Teet, et al.
(författare)
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Surface Effect on Spatial Length-Scales in a Two-Gap Superconductor
- 2016
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Ingår i: JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM. - : Springer. - 1557-1939 .- 1557-1947. ; 29:12, s. 3087-3091
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Tidskriftsartikel (refereegranskat)abstract
- The healing of two-band superconductivity near its interface is studied. It is demonstrated that the restoration of superconductivity gaps in the immediate vicinity of the interface is governed by two length scales: the first one diverges at critical temperature T (c) , while the second one diverges at T (c+)< T (c) . By moving away from the boundary, the temperature dependencies of characteristic lengths change so that singularity at T (c+) becomes removed in the bulk by arbitrary weak interband coupling. The asymptotes for the spatial behavior of gaps have been found analytically near the surface and approaching the bulk state.
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| 23. |
- Orgiani, P., et al.
(författare)
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The Role of Quantum Interference Effects in Normal-State Transport Properties of Electron-Doped Cuprates
- 2015
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1947 .- 1557-1939. ; 28:12, s. 3481-3486
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Tidskriftsartikel (refereegranskat)abstract
- The normal-state resistivity of thin films of the infinite-layer electron-doped cuprate Sr (1-x) La (x) CuO (2 +/-delta) has been investigated. Under-doped samples, which clearly show a metal-to-insulator transition (MIT) at low temperatures, have allowed the determination of the fundamental physical mechanism behind the upturn of the resistivity, namely the quantum interference effects (QIEs) in three-dimensional systems. The occurrence of weak localization effects has been unambiguously proven by low-frequency voltage spectral density measurements, which show a linear dependence of the 1/f noise on the applied bias current at low temperatures. The identification of the QIEs at low temperatures has therefore allowed the determination of the high-temperature non-Fermi liquid metallic phase, which is dominated by a linear temperature dependence of the resistivity for all of the samples investigated.
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| 24. |
- Oubelkacem, A., et al.
(författare)
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The Magnetic Properties of Multi-surface Transverse Ferroelectric Ising Thin Films
- 2015
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 28:3, s. 877-883
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Tidskriftsartikel (refereegranskat)abstract
- The effective field theory (EFT) based on the transverse Ising model (TIM) is used to study the layer and average polarizations of multi-surface ferroelectric thin film. The effects of the transverse fields and the exchange interactions on the polarization are discussed. It is obvious that the polarizations are affected explicitly by the TIM parameters, and the larger the exchange interactions, the larger the layer and average polarizations. Our theoretical predictions may be a reference for future work in studying the phase transition properties of ferroelectric thin films.
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| 25. |
- Ukleev, V., et al.
(författare)
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Imprinted Magnetic Anisotropy and Zigzag Domain Structure of Amorphous TbCo Films
- 2015
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Ingår i: Journal of Superconductivity and Novel Magnetism. - : Springer Science and Business Media LLC. - 1557-1939 .- 1557-1947. ; 28:12, s. 3571-3577
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the magnetic anisotropy and domain structure of amorphous Tb (x) Co(1-x) films grown in external in-plane magnetic field by high-frequency ion sputtering. Films with different thicknesses 100 and 500 nm and rare-earth element concentrations x = 12 % and x = 34 % present strong imprinted in-plane uniaxial anisotropy. Measurements of magnetic properties and domain structure imaging were performed by means of longitudinal and polar magneto-optical Kerr effect (MOKE). The coercivity fields increase by an order of magnitude for the higher Tb concentration and increase with film thickness (H (c) along the hard axis are 495, and 580 Oe, for 100 and 500 nm, with x = 34 % and 65, and 95 Oe for 100 and 500 nm with x = 12 %, respectively). Polar MOKE measurements revealed the existence of an out-of-plane magnetization component for the films with a Tb concentration of 34 % in lower fields. Large-scale domain structure of TbCo films with imprinted anisotropy was also studied as a function of applied field. Kerr imaging shows a zigzag domain structure of Tb12Co88 films, while no domains were found in Tb34Co66 samples. We also demonstrate that the zigzag angle depends on the film thickness. We suggest that domain structure in these films is determined by the interplay of imprinted and local magnetic anisotropies as well as exchange interaction.
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