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| 2. |
- Nilsen, G. J., et al.
(författare)
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Pair correlations, short-range order, and dispersive excitations in the quasi-kagome quantum magnet volborthite
- 2011
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 84:17
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Tidskriftsartikel (refereegranskat)abstract
- We present spatial and dynamic information on the s = 1/2 distorted kagome antiferromagnet volborthite, Cu3V2O7(OD)(2) center dot 2D(2)O, obtained by polarized and inelastic neutron scattering. The instantaneous structure factor, S(Q), is dominated by nearest-neighbor pair correlations, with short-range order at wave vectors Q(1) = 0.65(3) angstrom(-1) and Q(2) = 1.15(5) angstrom(-1) emerging below 5 K. The excitation spectrum, S(Q,omega), reveals two steep branches dispersing from Q(1) and Q(2), and a flat mode omega(f) = 5.0(2) meV. The results allow us to identify the crossover at T* similar to 1 K in V-51 NMR and specific-heat measurements as the buildup of correlations at Q(1). We compare our data to theoretical models proposed for volborthite, and also demonstrate that the excitation spectrum can be explained by spin-wave-like excitations with anisotropic exchange parameters, as suggested by recent local-density calculations.
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| 3. |
- Babkevich, P., et al.
(författare)
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Dimensional Reduction in Quantum Dipolar Antiferromagnets
- 2016
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 116:19
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Tidskriftsartikel (refereegranskat)abstract
- We report ac susceptibility, specific heat, and neutron scattering measurements on a dipolar-coupled antiferromagnet LiYbF4. For the thermal transition, the order-parameter critical exponent is found to be 0.20(1) and the specific-heat critical exponent -0.25(1). The exponents agree with the 2D XY/h(4) universality class despite the lack of apparent two-dimensionality in the structure. The order-parameter exponent for the quantum phase transitions is found to be 0.35(1) corresponding to (2 + 1)D. These results are in line with those found for LiErF4 which has the same crystal structure, but largely different T-N, crystal field environment and hyperfine interactions. Our results therefore experimentally establish that the dimensional reduction is universal to quantum dipolar antiferromagnets on a distorted diamond lattice.
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| 5. |
- Kamstrup, P, et al.
(författare)
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Biomarkers of Clot Activation and Degradation and Risk of Future Major Cardiovascular Events in Acute Exacerbation of COPD: A Cohort Sub-Study in a Randomized Trial Population
- 2022
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Ingår i: Biomedicines. - : MDPI AG. - 2227-9059. ; 10:8
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Tidskriftsartikel (refereegranskat)abstract
- Cardiovascular diseases are common in patients with chronic obstructive pulmonary disease (COPD). Clot formation and resolution secondary to systemic inflammation may be a part of the explanation. The aim was to determine whether biomarkers of clot formation (products of von Willebrand Factor formation and activation) and clot resolution (product of fibrin degeneration) during COPD exacerbation predicted major cardiovascular events (MACE). The cohort was based on clinical data and biobank plasma samples from a trial including patients admitted with an acute exacerbation of COPD (CORTICO-COP). Neo-epitope biomarkers of formation and the activation of von Willebrand factor (VWF-N and V-WFA, respectively) and cross-linked fibrin degradation (X-FIB) were assessed using ELISAs in EDTA plasma at the time of acute admission, and analyzed for time-to-first MACE within 36 months, using multivariable Cox proportional hazards models. In total, 299/318 participants had samples available for analysis. The risk of MACE for patients in the upper quartile of each biomarker versus the lower quartile was: X-FIB: HR 0.98 (95% CI 0.65–1.48), VWF-N: HR 1.56 (95% CI 1.07–2.27), and VWF-A: HR 0.78 (95% CI 0.52–1.16). Thus, in COPD patients with an acute exacerbation, VWF-N was associated with future MACE and warrants further studies in a larger population.
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| 6. |
- Niklasson, GA, et al.
(författare)
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Surface roughness of pyrolytic tin dioxide films evaluated by different methods
- 2000
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Ingår i: THIN SOLID FILMS. - : ELSEVIER SCIENCE SA. - 0040-6090. ; 359:2, s. 203-209
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Tidskriftsartikel (refereegranskat)abstract
- The scaling of surface roughness in thin spray pyrolyzed fluorinated tin dioxide films of different thicknesses was obtained from atomic force microscopy. The data show that, within experimental uncertainties, the effective dimensionality of the surface i
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| 9. |
- Wojek, Bastian M., et al.
(författare)
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The J(eff)=1/2 insulator Sr3Ir2O7 studied by means of angle-resolved photoemission spectroscopy
- 2012
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 24:41, s. 415602-
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Tidskriftsartikel (refereegranskat)abstract
- The low-energy electronic structure of the J(eff) = 1/2 spin-orbit insulator Sr3Ir2O7 has been studied by means of angle-resolved photoemission spectroscopy. A comparison of the results for bilayer Sr3Ir2O7 with available literature data for the related single-layer compound Sr2IrO4 reveals qualitative similarities and similar J(eff) = 1/2 bandwidths for the two materials, but also pronounced differences in the distribution of the spectral weight. In particular, photoemission from the J(eff) = 1/2 states appears to be suppressed. Yet, it is found that the Sr3Ir2O7 data are in overall better agreement with band-structure calculations than the data for Sr2IrO4.
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