Japan Atomic Energy Agency

About: Japan Atomic Energy Agency is a government organization based out in Tōkai-mura, Japan. It is known for research contribution in the topics: Neutron & Laser. The organization has 7151 authors who have published 17791 publications receiving 259118 citations. The organization is also known as: JAEA & Nihon genshiryoku kenkyū kaihatsu kikō.

Magnetovolume effect in Mn 3 Cu 1 − x Ge x N related to the magnetic structure: Neutron powder diffraction measurements

Abstract: Magnetic structures in an antiperovskite system, ${\mathrm{Mn}}_{3}{\mathrm{Cu}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}\mathrm{N}$, with a large magnetovolume effect above $x=0.15$ have been studied by neutron powder diffraction measurement. The present neutron study revealed that not only a cubic crystal structure but also a ${\ensuremath{\Gamma}}^{5g}$ antiferromagnetic spin structure are key ingredients of the large magnetovolume effect in this itinerant electron system. The large magnetovolume effect is possibly ascribed to the geometrical frustration originating from the corner-shared octahedra of the antiperovskite structure.

Neutrino Signals from the Formation of a Black Hole: A Probe of the Equation of State of Dense Matter

Abstract: The gravitational collapse of a nonrotating, black-hole-forming massive star is studied by {nu}-radiation-hydrodynamical simulations for two different sets of realistic equation of state of dense matter. We show that the event will produce as many neutrinos as the ordinary supernova, but with distinctive characteristics in luminosities and spectra that will be an unmistakable indication of black hole formation. More importantly, the neutrino signals are quite sensitive to the difference of equation of state and can be used as a useful probe into the properties of dense matter. The event will be unique in that they will be shining only by neutrinos (and, possibly, gravitational waves) but not by photons, and hence they should be an important target of neutrino astronomy.

Bipartite magnetic parent phases in the iron oxypnictide superconductor

Abstract: Superconductivity in iron pnictide compounds occurs near a magnetic phase and magnetic spin fluctuations are prime candidates for the superconducting pairing mechanism. What does this mean now that a second magnetic phase, next to another superconducting phase, is found at higher doping levels?

Revealing the Dual Nature of Magnetism in Iron Pnictides and Iron Chalcogenides Using X-ray Emission Spectroscopy

Abstract: We report a Fe K$\ensuremath{\beta}$ x-ray emission spectroscopy study of local magnetic moments in various iron-based superconductors in their paramagnetic phases. Local magnetic moments are found in all samples studied: PrFeAsO, $\mathrm{Ba}{(\mathrm{Fe},\mathrm{Co})}_{2}{\mathrm{As}}_{2}$, LiFeAs, Fe${}_{1+x}$(Te,Se), and ${\mathrm{A}}_{2}{\mathrm{Fe}}_{4}{\mathrm{Se}}_{5}$ (where $\text{A}=\text{K}$, Rb, and Cs). The moment size is independent of temperature or carrier concentration but varies significantly across different families. Specifically, all iron pnictide samples have local moments of about 1${\ensuremath{\mu}}_{B}$/Fe, while FeTe and ${\mathrm{K}}_{2}{\mathrm{Fe}}_{4}{\mathrm{Se}}_{5}$ families have much larger local moments of $\ensuremath{\sim}2{\ensuremath{\mu}}_{B}$/Fe and $\ensuremath{\sim}3.3{\ensuremath{\mu}}_{B}$/Fe, respectively. Our results illustrate the importance of multiorbital physics in describing magnetism of these compounds.