| 1. |
|
|
| 2. |
- Burkert, Till, et al.
(författare)
-
Giant Magnetic Anisotropy in Tetragonal FeCo Alloys
- 2004
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 93:2, s. 027203-
-
Tidskriftsartikel (refereegranskat)abstract
- The magnetic anisotropy energy (MAE) of hcp Gd was calculated from first principles using the full-potential linear muffin-tin orbital method. It was found that the principal contributions to the MAE are the dipole-dipole interaction between the localized 4f spins and the spin-orbit interaction of the valence band states. The dipole contribution has the form 1/2K(1)(d)(1-cos 2 theta), where theta is the angle between the magnetization direction and the c axis. The contribution of the spin-orbit interaction is shown to arise from the polarization of the conduction band that becomes exchange split due to exchange interaction with the localized 4f electrons. We argue that this leads to significant contributions from higher order anisotropy constants. An imposed reduced 4f moment leads to a repopulation of the electronic states at the Fermi level and a reduced exchange splitting of the valence states, which we demonstrate leads to a modification of the MAE. This modification is in qualitative agreement with the observed temperature dependence of the MAE. In addition, the dependence of the MAE on the c/a ratio has been studied.
|
|
| 3. |
- Eklund, Fredrik, et al.
(författare)
-
Variation in fracture rates by country may not be explained by differences in bone mass
- 2009
-
Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 0171-967X .- 1432-0827. ; 85:1, s. 10-16
-
Tidskriftsartikel (refereegranskat)abstract
- It is unclear whether the high fracture incidence in Sweden compared with other countries is related to low bone mass. We present and compare bone mineral density (BMD, g/cm(2)) at the femoral neck in a mainly osteoporotic referral population consisting of 2,031 men and 6,932 women with that of previous population-based cohorts. BMD measurements were collected at a single study center in Sweden, and data on validated hip fractures were collected from the corresponding health-care district and the cohort investigated. The BMD values of our cohort were similar to those of population-based cohorts from other countries. In contrast, the total incidence of hip fractures in 80-year-old women and men in the health-care district where our BMD measurements were performed was high (1.8% and 0.9%, respectively). The correlation between age and BMD was more negative in men aged 20-49 years than in women of the same age group (-0.011 vs. -0.006 g/cm(2) yearly, P < 0.001). In contrast, at 50-80 years of age, more negative regression coefficients were seen in women (-0.007 vs. -0.004 g/cm(2) yearly, P < 0.001 for comparison). In conclusion, a low BMD may not be the key factor explaining Sweden's comparatively high fracture incidence. In our cross-sectional data, age trends in BMD at the femoral neck differ between men and women. It would be highly interesting to further study the underlying causes of the global variations in fracture incidence rates.
|
|
| 4. |
- Hallkvist, Olle M., et al.
(författare)
-
Dairy product intake and bone properties in 70-year-old men and women
- 2018
-
Ingår i: Archives of Osteoporosis. - : Springer. - 1862-3514 .- 1862-3522. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- SUMMARY: In the present population-based study including 70-year-old men and women, total dairy product intake was associated with a weak positive association with tibia trabecular and cortical cross-sectional areas.PURPOSE: Milk consumption has recently been suggested to increase fracture risk. Therefore, we aimed to investigate associations between dairy product consumption and peripheral bone properties. Furthermore, we explored whether consumption of milk and fermented dairy products affected bone properties differently.METHODS: The Healthy Aging Initiative is a population-based, cross-sectional study investigating the health of 70-year-old men and women. Out of the 2904 individuals who met the inclusion criteria, data on self-reported daily dairy product consumption (dl/day), peripheral quantitative computed tomography (pQCT) examinations at the 4 and 66% scan sites of the tibia and radius, and dual-energy X-ray absorptiometry (DXA) scans were collected from 2040 participants. Associations between dairy product consumption and bone properties were examined using multiple linear regression models adjusted for sex, muscle area, meal size, dietary protein proportion, current smoking status, and objectively measured physical activity.RESULTS: Total dairy product intake was associated with larger trabecular (2.296 (95% CI, 0.552-4.039) mm2, per dl/day increase, p = 0.01) and cortical cross-sectional areas (CSAs) in the tibia (1.757 (95% CI, 0.683-2.830 mm2, p = 0.001) as measured by pQCT and higher areal bone mineral density (aBMD) of the radius (3.231 (95% CI, 0.764-5.698) mg/cm2, p = 0.01) as measured by DXA. No other measurement in the tibia, radius, femoral neck, or lower spine was associated significantly with dairy product intake. Bone properties did not differ according to the type of dairy product consumed.CONCLUSION: No evidence of a negative association between dairy product consumption and bone health was found. Furthermore, total dairy product consumption was associated with increased CSAs in the tibia, regardless of dairy product type. Collectively, our findings indicate the existence of a weak but significant positive association between dairy product consumption bone properties in older adults.
|
|
| 5. |
|
|
| 6. |
- Andersson, Gabriella, et al.
(författare)
-
Perpendicular magnetocrystalline anisotropy in tetragonally distorted Fe-Co alloys
- 2006
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 96:3
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the experimental realization of tetragonal Fe-Co alloys as a constituent of Fe(0.36)Co(0.64)/Pt superlattices with huge perpendicular magnetocrystalline anisotropy energy, reaching 210 mu eV/atom, and a saturation magnetization of 2.5 mu(B)/atom at 40 K, in qualitative agreement with theoretical predictions. At room temperature the corresponding values 150 mu eV/atom and 2.2 mu(B)/atom are achieved. This suggests that Fe-Co alloys with carefully chosen combinations of composition and distortion are good candidates for high-density perpendicular storage materials.
|
|
| 7. |
- Andersson, Per H., et al.
(författare)
-
Effect of hydrogenation on the magnetic state in cubic Pd3Mn
- 1999
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 60:9, s. 6765-6769
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of hydrogenation on the magnetic and electronic state of cubic Pd3Mn has been calculated using a full-potential linear augmented plane-wave method in the local spin-density approximation. A complex magnetic structure is found in very good agreement with experiment. For the nonhydrogenated system we observe a noncommensurate spin spiral although we cannot identify the ground state of the spin structure as the total energy of the trigonal spin structure is almost degenerate with the total energy of the tetragonal spin structure. When hydrogenated the direction of the spiral is aligned along the (001) axis. The spin structures agree with experiment and are connected to features on the calculated Fermi surfaces.
|
|
| 8. |
- Andersson, P. H., et al.
(författare)
-
The effect of hydrogenation on the crystal structure and magnetic state in Pd3Mn
- 2001
-
Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 226-230:Part 1, s. 1040-1041
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of hydrogenation on the crystalstructure and magneticstate of Pd3Mn has been calculated using a full-potential linear augmented plane wave method in the local spin density approximation.When hydrogenated the system is observed to transform from the tetragonal Al3Zr structure to the cubic Cu3Au structure. When hydrogen is removed the system remains in a meta-stable cubic phase for an extended period of time. The structural transformations are associated with a change in the magneticstate. Our theoretical results of magnetic as well as crystalstructure stability are in agreement with experiments, especially the destabilization of the tetragonal structure for increased hydrogen concentration and complex magneticstructure of the cubic phases. The latter is analyzed in terms of Fermi surface nesting.
|
|
| 9. |
|
|
| 10. |
- Andersson, Per H., et al.
(författare)
-
Theoretical study of structural and electronic properties of VHx
- 1998
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 58:9, s. 5230-5235
-
Tidskriftsartikel (refereegranskat)abstract
- We have calculated the change in the electronic structure and the distortion of the lattice in vanadium upon hydrogenation from first principles using the full-potential linear muffin-tin-orbital method and the linear augmented plane-wave method in the local-density approximation. The calculated hydrogen induced volume expansions agree with experiment and the change in the c/a ratio is also in good agreement with observations where such are available for single phase VHx. Among several changes in the electronic structure, we note a hybridization of the d band of vanadium with the hydrogen 1s band. We also observe an antiferromagnetically ordered moment at V/Vexp=1.08. The possibility of producing magnetic V by means of hydrogenation in combination with epitaxial growth is suggested.
|
|
