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| 2. |
- Forslund, Ola Kenji, et al.
(författare)
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Co-existence of short- and long-range magnetic order in LaCo2P2
- 2021
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 96:12, s. 125864-
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Tidskriftsartikel (refereegranskat)abstract
- The ferromagnetic (FM) nature of the metallic LaCo2P2 was investigated with the positive muon spin rotation, relaxation and resonance (μ+SR) technique. Transverse and zero field μ+ SR measurements revealed that the compound enters a long range FM ground state at K, consistent with previous studies. Based on the reported FM structure, the internal magnetic field was computed at the muon sites, which were predicted with first principles calculations. The computed result agree well with the experimental data. Moreover, although LaCo2P2 is a paramagnet at higher temperatures T > 160 K, it enters a short range ordered (SRO) magnetic phase for K. Measurements below the vicinity of revealed that the SRO phase co-exists with the long range FM order at temperatures 124 K . Such co-existence is an intrinsic property and may be explained by an interplay between spin and lattice degree of freedoms.
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| 3. |
- Forslund, Ola Kenji, 1990, et al.
(författare)
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Pressure driven magnetic order in Sr 1 - x Ca x Co 2 P 2
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic phase diagram of Sr1-xCaxCo2P2 as a function of hydrostatic pressure and temperature is investigated by means of high pressure muon spin rotation, relaxation and resonance (μ+SR). The weak pressure dependence for the x≠ 1 compounds suggests that the rich phase diagram of Sr1-xCaxCo2P2 as a function of x at ambient pressure may not solely be attributed to chemical pressure effects. The x= 1 compound on the other hand reveals a high pressure dependence, where the long range magnetic order is fully suppressed at pc 2≈ 9.8 kbar, which seem to be a first order transition. In addition, an intermediate phase consisting of magnetic domains is formed above pc 1≈ 8 kbar where they co-exist with a magnetically disordered state. These domains are likely to be ferromagnetic islands (FMI) and consist of an high- (FMI-1) and low-temperature (FMI-2) region, respectively, separated by a phase boundary at Ti≈ 20 K. This kind of co-existence is unusual and is originating from a coupling between lattice and magnetic degrees of freedoms.
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| 4. |
- Forslund, Ola Kenji, et al.
(författare)
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Pressure driven magnetic order in Sr1-xCaxCo2P2
- 2022
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic phase diagram of Sr1-xCaxCo2P2 as a function of hydrostatic pressure and temperature is investigated by means of high pressure muon spin rotation, relaxation and resonance (mu+SR). The weak pressure dependence for the x not equal 1- compounds suggests that the rich phase diagram of Sr1-xCaxCo2P2 as a function of x at ambient pressure may not solely be attributed to chemical pressure effects. The x = 1 compound on the other hand reveals a high pressure dependence, where the long range magnetic order is fully suppressed at p(c2) approximate to 9.8 kbar, which seem to be a first order transition. In addition, an intermediate phase consisting of magnetic domains is formed above p(c1) approximate to 8 kbar where they co-exist with a magnetically disordered state. These domains are likely to be ferromagnetic islands (FMI) and consist of an high- (FMI-(1)) and low-temperature (FMI-(2)) region, respectively, separated by a phase boundary at T-i approximate to 20 K. This kind of co-existence is unusual and is originating from a coupling between lattice and magnetic degrees of freedoms.
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| 6. |
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| 7. |
- Namkoong, H, et al.
(författare)
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DOCK2 is involved in the host genetics and biology of severe COVID-19
- 2022
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 609:7928, s. 754-
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Tidskriftsartikel (refereegranskat)abstract
- Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge1–5. Here we conducted a genome-wide association study (GWAS) involving 2,393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3,289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target.
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| 8. |
- Sakamoto, Kazuyuki, et al.
(författare)
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Abrupt Rotation of the Rashba Spin to the Direction Perpendicular to the Surface
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:9, s. 096805-
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Tidskriftsartikel (refereegranskat)abstract
- The polarization vector of the Rashba spin, which must be parallel to the two-dimensional (2D) plane in an ideal system, is found to change abruptly and definitely to the direction perpendicular to the surface at the K̅ point of the Brillouin zone of a real hexagonal system, the Tl/Si(111)-(1×1) surface. This finding obtained experimentally by angle-resolved and spin-resolved photoemission measurements is fully confirmed by a first-principles theoretical calculation. We found that the abrupt rotation of the Rashba spin is simply understood by the 2D symmetry of the hexagonal structure.
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| 9. |
- Sugiyama, Jun, et al.
(författare)
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Magnetic phases in Sr1-xCaxCo2P2 studied by mu+SR
- 2015
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Ingår i: 20TH INTERNATIONAL CONFERENCE ON MAGNETISM, ICM 2015. - : Elsevier. ; , s. 426-434
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Konferensbidrag (refereegranskat)abstract
- In order to elucidate the dependence of the magnetic ground state on the Ca content (x) in Sr1-xCaxCo2P2 (0 <= x <= 1, ThCr2Si2-type structure), we have performed muon spin rotation and relaxation (mu+SR) experiments on Sr1-xCaxCo2P2 powder samples mainly in a zero applied field. The end member compound, SrCo2P2, is found to be paramagnetic down to 19 mK. As x increases, such a paramagnetic ground state is observed down to 1.8 K until x = 0.45. Then, as x increases further, a short-range antiferromagnetic (AF) ordered phase appears at low temperatures for 0.48 <= x <= 0.75, and finally, a long-range AF ordered phase is stabilized for x > 0.75. The internal magnetic field of the other end member compound, CaCo2P2, is well consistent with that of the A-type AF order state, which was proposed from neutron scattering experiments. The phase diagram determined with mu+SR is different from that proposed by macroscopic measurements. For an isostructural compound, LaCo2P2, static magnetic order is found to be formed below similar to 130 K.
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| 10. |
- Sugiyama, Jun, et al.
(författare)
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Variation of magnetic ground state of Sr1-xCaxCo2P2 determined with mu(+) SR
- 2015
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 91:14
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Tidskriftsartikel (refereegranskat)abstract
- In order to study the variation of a microscopic internal magnetic field with the Ca content (x), we have systematically measured muon-spin rotation and relaxation (mu+SR) spectra for Sr1-xCaxCo2P2 (0 <= x <= 1) powder samples mainly in a zero external field. As x increases from 0, a Pauli-paramagnetic phase is observed even at the lowest T measured (1.8 K) until x = 0.45; then, a short-range antiferromagnetic (AF) ordered phase appears for 0.48 <= x <= 0.75, and finally a long-range AF ordered phase is stabilized for x >= 0.75. The evolution of the magnetic order is connected to the shrinking of the c-axis length as a function of x, which naturally enhances the AF interaction between the two adjacent Co planes.
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