Search

This study examined the effects of birth weight on body composition, physical fitness, and sarcopenia in adulthood among young Japanese women. Seventy young adult women (birth weight <2500 g classified as low-birth-weight group [L-BW, n = 13] and ≥2500 g classified as not low-birth-weight group [NL-BW, n = 57]) were evaluated for body composition, physical fitness, and sarcopenia. Skeletal muscle mass was significantly greater (p<0.05) in the NL-BW group than in the L-BW group for all body sites. Effect sizes for the differences in skeletal muscle mass between the two groups were all larger in the NL-BW group than in the L-BW group (0.86–1.44). Knee extension muscle strength was higher in the NL-BW group than in the L-BW group (p = 0.04), but there were no differences between groups with respect to other physical fitness indicators (p>0.05). Except for SMI (p<0.05), other sarcopenia diagnostic evaluations did not differ between the two groups (p>0.05). In conclusion, L-BW female infants were shorter in standing height and smaller in skeletal muscle mass in terms of morphology at the time of young adulthood compared to NL-BW female infants. In addition, in terms of physical fitness, those with L-BW also had a lower-limb power score and a higher proportion of low skeletal muscle mass. Thus, it was suggested that low birth weight infants may be at risk of needing nursing care in old age (i.e., a high predicted incidence of sarcopenia) as well as thinness problems in the fertile generation. [ABSTRACT FROM AUTHOR]

Mn4N/(Mn,Cu)4N epitaxial bilayer structures with (Mn,Cu)4N compositions below and above the magnetization compensation composition were prepared on SrTiO3(001) substrates by molecular beam epitaxy. The thickness of the (Mn,Cu)4N layer was fixed at approximately 20 nm, while that of the Mn4N layer was changed from 7.5 to 19.6 nm. Cross-sectional elemental mapping proved that the diffusion of Cu from the (Mn,Cu)4N layer to the Mn4N layer was negligible. The magnetization curves showed that the magnetic moments of Mn4N and (Mn,Cu)4N were antiferromagnetically coupled, independent of the Mn4N film thickness, indicating a synthetic ferrimagnetic structure. The dependence of magnetic order on Mn4N film thickness was confirmed by surface-sensitive measurements using polar magneto-optical Kerr effect and x-ray magnetic circular dichroism. This is due to the change in the layer with dominant magnetization and the strength of the antiferromagnetic coupling. The temperature dependence of the anomalous Hall effect showed that the antiferromagnetic coupling was retained in the Mn4N(7.5 nm)/(Mn,Cu)4N(22.4 nm) structure over a wide temperature range of 10–350 K. [ABSTRACT FROM AUTHOR]

We focus on rare-earth-free anti-perovskite Mn4−xNixN epitaxial films, which can be used for ultrafast current-induced domain wall motion (CIDWM) in magnetic strips. The magneto-transport properties of these materials are very important for a deep understanding of CIDWM. In this study, we investigated the magneto-transport properties of Mn4−xNixN epitaxial films grown on SrTiO3(001) and MgO(001) substrates through anisotropic magnetoresistance (AMR) measurements at temperatures between 2 and 300 K. In samples with a small Ni composition such as x = 0.05−0.1, the AMR ratio of Mn4−xNixN drastically decreased with increasing temperature. We also analyzed the twofold and fourfold symmetries in the AMR curves. Fourfold symmetry is caused by tetragonal crystal fields and is unique to anti-perovskite 3d-metal nitrides such as Mn4N and Fe4N. Only slight fourfold symmetry was observed in Mn4−xNixN. We also performed first-principles calculations with the Vienna ab initio simulation package (VASP) to obtain the projected density of states (PDOS) of d orbitals in Mn4−xNixN, which is responsible for the magnetism of these materials. We conclude that these results are due to the Ni atoms, which function as magnetic impurities and lead to a noticeable change in PDOS, as proved by VASP calculation. [ABSTRACT FROM AUTHOR]

Magnetization control by electric current or spin current is an attractive technology with potential applications in memory and logic devices, and Mn4N has attracted much attention in recent years as a candidate material for current-induced magnetization switching and magnetic domain wall motion, as well as a skyrmion material. For these applications, a bilayer structure of Mn4N and heavy metals must be formed with high crystalline quality. In this study, we have achieved the epitaxial growth of Mn4N thin films on MgO(001) with a Pt underlayer. The reflection high-energy electron diffraction images and x-ray diffraction ω-rocking curves show that the Mn4N films fabricated on the Pt underlayers exhibit higher crystalline quality than the Mn4N films directly formed on the MgO. Furthermore, anomalous Hall effect loops with bump-like structures were observed. This is considered to be due to the topological spin texture. The Mn4N/Pt epitaxial bilayer structure has potential for use in spin–orbit torque applications and is a candidate configuration for topological spin textures. [ABSTRACT FROM AUTHOR]

Mn4N thin films meet the requirements for efficient current-driven magnetic domain wall motion, such as perpendicular magnetic anisotropy and small magnetization. To demonstrate efficient field-free spin–orbit torque (SOT)-driven domain wall motion, the thickness of the Mn4N layer must be reduced. In this study, we focus on the fabrication of Mn4N ultrathin films on SrTiO3(001) substrates and demonstrate the epitaxial growth of Mn4N films as thin as around 4 nm. Surprisingly, the sign of the anomalous Hall resistivity of Mn4N reverses when the thickness of Mn4N decreases from approximately 8 to 4 nm. X-ray magnetic circular dichroism measurements suggest that the magnetic structure of Mn4N with a thickness of around 4 nm is different from that of conventional ferrimagnetic Mn4N films. The results obtained in this study are of great importance when considering the use of SOT and the interfacial Dzyaloshinskii–Moriya interaction in Mn4N ultrathin films. [ABSTRACT FROM AUTHOR]