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丸山 龍治
no journal, ,
The polarized neutron off-specular scattering measurement of Fe/Ge periodic multilayers revealed that the frerromagnetic (FM) interlayer exchange coupling between neighboring Fe layers grew with decreasing Ge thickness less than 2 nm. The FM interlayer exchange coupling observed here contributed to the presence of the saturation magnetization and soft magnetic properties comparable to the bulk. This offers a possibility to keep the spontaneous magnetization for the multilayer with a thin bilayer thickness and hence to extend the bandwidth of the polarizing supermirror. In this presentation, the discussion on the FM interlayer exchange coupling of the Fe/Ge multilayer and its performance as a polarizing supermirror will be followed by the one on a recently tested possibility to use an Fe/Cr multilayer for the neutron-spin polarizer.
樹神 克明
no journal, ,
Magnetic pair distribution function (mPDF) shows a real space magnetic correlation between magnetic moments with a distance r. Roughly speaking, ferromagnetic and antiferromagnetic correlations between the paired magnetic moments give positive and negative magnetic correlation peaks, respectively. The mPDF analysis is appropriate for the determination of magnetic structures of the materials with magnetic short-range orderings, for example, spin glass, frustrated magnets, magnetic nanoparticles, and so on. We performed mPDF analysis on frustrated metallic magnets with short-range orderings.
金子 耕士
no journal, ,
Polarized neutron offer a unique capability to gain insights into matter. This technique is widely applied to investigate magnetism and its correlated phenomena in condensed matter, often requires additional sample environments, such as low temperature, magnetic fields, and high pressure. At the research reactor JRR-3, we have restored a polarized neutron option on the triple-axis spectrometer TAS-1. Recently, we introduced a liquid-helium-free sample environment, including a 10~T vertical-field magnet and top-load cryostats with a base temperature below 1.5 K, and 3 T horizontal-field magnet, all of which share a common design for the sample space. These sample environments allow us to perform polarized neutron scattering experiments under complex conditions. I will present recent data collected on TAS-1.
MgGe with the Shastry-Sutherland lattice廣瀬 雄介; 本多 史憲*; 摂待 力生*; 中島 多朗*; 齋藤 開*
no journal, ,
Ce
MgGe crystallizes in the tetragonal MoFeB type structure, where Ce atoms form a frustrated arrangement, the Shastry-Sutherland lattice (SSL). The compound exhibits an antiferromagnetic ordering at TN=9.5 K and a complex magnetic phase diagram. To investigate the magnetic structure, we performed neutron scattering measurements on a single crystalline CeMgGe. A magnetic scattering, which grows below TN, is observed on a nuclear scattering, meaning that a magnetic propagation vector is zero. The spin-polarized neutron scattering experiment reveals that the magnetic moment of Ce atoms is aligned in the c plane. From the neutron scattering measurement, we determine the magnetic structure of CeMgGe with an ordered moment of about 1.5mB, which is almost consistent with the saturated magnetic moment.
廣井 孝介; 熊田 高之; 中部 倫太郎; 元川 竜平; 奥 隆之
no journal, ,
In small-angle neutron scattering (SANS) measurement, incoherent scattering components from samples are observed as background that does not have structural information. The incoherent scattering component can be experimentally estimated and separated from the coherent scattering one by separately observing spin-flip and non-spin-flip scattering components using polarization analysis. There are some SANS instruments that have such polarization analysis option in Japan, BL15 TAIKAN at Material and Life science Experimental Facility (MLF) of J-PARC and SANS-J of JRR-3. In this presentation, we will introduce polarization analysis setups of TAIKAN and SANS-J and show recent experimental results.
田端 千紘; 高田 秀佐*; 下条 豊; 大河原 学*; 池田 陽一*; 猪野 隆*; 河村 聖子; 奥 隆之; 藤田 全基*; 金子 耕士
no journal, ,
Neutron scattering is a powerful tool to investigate magnetism, and its capabilities are enhanced when combined with a magnetic field, allowing for deeper insights into magnetic materials. Traditionally, such experiments use a vertical field magnet on a triple-axis spectrometer to explore wide Q-omega space at high magnetic fields. However, horizontal field magnets are less common due to limitations like lower maximum fields and restricted access in the horizontal scattering plane. Despite these challenges, there is growing interest in horizontal-field magnets for studying complex magnetic structures, such as topological spin textures, and for unique applications with polarized neutrons, like separating nuclear and magnetic components or detecting magnetic chirality. We have introduced a new horizontal-field system for neutron scattering that features an HTC superconducting magnet and a cryogen-free VTC. The 3T magnet, designed by HTS-110, accommodates a 3He spin filter with a low fringe field and a 60-degree horizontal window for polarization channel px measurements. The VTC fits the magnet's bore and shares sample space with existing VTCs at JRR-3, enabling shared use of sample sticks and 3He inserts. This system provides horizontal fields up to 3 T, temperatures down to 0.3 K, and compatibility with the chopper spectrometer at MLF, J-PARC, for future testing.
吉川 貴史
no journal, ,
In spintronics, transmission of spin information via the spin angular momentum of itinerant electrons, known as spin current, has long been of critical importance, particularly in nanoscale and mesoscale device structures and junctions. However, since the demonstration of spin-current transport by magnons in a magnetic material Y
Fe
O
in 2010, it has become evident that dynamics of elementary excitations, such as magnons, in magnetic materials also play a crucial role in spintronic functionalities. One notable example is the spin Seebeck effect (SSE), in which magnon dynamics in a magnet under a temperature gradient drives a spin current. In this talk I will discuss recent research in which neutron scattering has been employed to unravel the complicated temperature dependence of the SSE signals observed in magnetic garnets YFeO and TbFeO such as sign reversal and significant signal-reduction at low temperatures. In the latter part of the presentation, I will introduce the generation of spin currents via nuclear spins and discuss its potential development into the field of polarized neutron scattering.