Slater-Pauling-like Behavior of Spin Hall Conductivity in Pt-based Superlattices

The intrinsic spin Hall effect in the bulk systems of late  transition metals (Os, Ir, Pt, and Au) as well as the Pt-based superlattices were investigated by using first-principle calculations. By comparing the computed spin Hall conductivities of Pt−M superlattices (M=Os, Ir, and Au) with different compositions and those obtained from atomic bulk composition, we saw that the spin Hall conductivities (SHCs) follow the behavior described by the Slater-Pauling curve, the maximum of which is at pure Pt bulk. From the examination of the band structures of the considered systems, we found that the origin of this behavior comes from the variation of the band structures as a direct consequence of the change of the number of electrons and hybridization effects

Spin-spiral structures in free-standing Fe(110) monolayers

科研費報告書収録論文(課題番号:16310081/研究代表者:白井正文/ナノ磁性材料におけるスピン構造とそのダイナミクスに関する理論研究

Low-Mass Star Formation, Triggered by Supernova in Primordial Clouds

The evolution of a gas shell, swept by the supernova remnant of a massive first generation star, is studied with H_2 and HD chemistry taken into account. When a first-generation star explodes as a supernova, H_2 and HD molecules are formed in the swept gas shell and effectively cool the gas shell to temperatures of 32 K - 154 K. If the supernova remnant can sweep to gather the ambient gas, the gas shell comes to be dominated by its self-gravity, and hence, is expected to fragment. Our result shows that for a reasonable range of temperatures (200 K - 1000 K) of interstellar gas, the formation of second-generation stars can be triggered by a single supernova or hypernova.Comment: 38pages, 10 figures, The Astrophysical Journal, accepted 8 Dec. 200

Jahn-Teller driven perpendicular magnetocrystalline anisotropy in metastable ruthenium

A metastable phase of body-centered-tetragonal ruthenium (bct Ru) is identified to exhibit a large perpendicular magnetocrystalline anisotropy (PMCA), whose energy E-MCA is as large as 150 mu cV/atom, which is two orders of magnitude greater than those of 3d magnetic metals. Further investigation over the range of tetragonal distortion suggests that the appearance of magnetism in the bct Ru is governed by the Jahn-Teller spit e(g) orbitals. Moreover, from band analysis, MCA is mainly determined by an interplay between two e(g) states, d(x)(-y)(2)(2)and d(z)(2) states, as a result of level reversal associated with tetragonal distortion.open1

Collapse and Fragmentation of Rotating Magnetized Clouds. I. Magnetic Flux - Spin Relation

We discuss evolution of the magnetic flux density and angular velocity in a molecular cloud core, on the basis of three-dimensional numerical simulations, in which a rotating magnetized cloud fragments and collapses to form a very dense optically thick core of > 5 times 10 ^10 cm^-3 . As the density increases towards the formation of the optically thick core, the magnetic flux density and angular velocity converge towards a single relationship between the two quantities. If the core is magnetically dominated its magnetic flux density approaches 1.5 (n/5 times 10^10 cm^-3)^1/2 mG, while if the core is rotationally dominated the angular velocity approaches 2.57 times 10^-3, (n/5 times 10^10 cm^-3)^1/2 yr^-1, where n is the density of the gas. We also find that the ratio of the angular velocity to the magnetic flux density remains nearly constant until the density exceeds 5 times 10^10 cm^-3. Fragmentation of the very dense core and emergence of outflows from fragments are shown in the subsequent paper.Comment: 17 pages, 12 figures, accepted for publication in MNRA