Elastic and inelastic neutron scattering experiments under high pressure in the frustrated antiferromagnet CuFeO

Terada, Noriki*; Khalyavin, D. D.*; Manuel, P.*; Asai, Shinichiro*; Masuda, Takatsugu*; Saito, Hiraku*; Nakajima, Taro*; Osakabe, Toyotaka

Physical Review B, 110(2), p.024406_1 - 024406_9, 2024/07

https://doi.org/10.1103/PhysRevB.110.024406

The frustrated antiferromagnet CuFeO exhibits pressure-induced complex magnetic phase transitions from the commensurate collinear (CM1) phase to several incommensurate noncollinear phases. To study the effect of high pressure on magnetic interactions, we performed neutron diffraction and inelastic neutron scattering experiments under high-pressure conditions. With increasing pressure, the CM1 ground state becomes less stable against application of a magnetic field even below the critical pressure ( 3 GPa), as proved by the significant reduction in the critical magnetic field from =7.5 T to 4.5 T at 2.1 GPa. Additionally, the energy gap in the spin-wave dispersion relation is reduced from 1.0 to 0.88 meV by the application of a pressure of = 2.1 GPa. Comparing the experimental results with spin-wave calculations revealed that the change in the spin-wave excitation can be explained by the reduction in either the uniaxial anisotropy term or the degree of separation in the nearest-neighbor exchange interactions.

Local structural changes in V-Ti-Cr alloy hydrides with hydrogen absorption/desorption cycling

Ikeda, Kazutaka*; Sashida, Sho*; Otomo, Toshiya*; Oshita, Hidetoshi*; Honda, Takashi*; Hawai, Takafumi*; Saito, Hiraku*; Ito, Shinichi*; Yokoo, Tetsuya*; Sakaki, Koji*; et al.

International Journal of Hydrogen Energy, 51(Part A), p.79 - 87, 2024/01

https://doi.org/10.1016/j.ijhydene.2023.10.318

Square and rhombic lattices of magnetic skyrmions in a centrosymmetric binary compound

Takagi, Rina*; Matsuyama, Naofumi*; Ukleev, V.*; Yu, L.*; White, J. S.*; Francoual, S.*; Mardegan, J. R. L.*; Hayami, Satoru*; Saito, Hiraku*; Kaneko, Koji; et al.

Nature Communications (Internet), 13, p.1472_1 - 1472_7, 2022/03

https://doi.org/10.1038/s41467-022-29131-9

Cross-sectional hydrogen content and mass density profiles of DLC film by neutron and X-ray reflectivity

Ozeki, Kazuhide*; Yonemura, Masao*; Masuzawa, Toru*; Saito, Hidetoshi*; Ogoe, Yasuharu*; Hirakuri, Kenji*; Takeda, Masayasu

no journal, , 

Hydrogen content in the DLC film is very important factor because it greatly influences on its mechanical properties and microstructure such as hardness, wear resistance, surface roughness, and sp3/sp2 ratio. In the present study, we prepared the DLC film using plasma CVD technique varying H/CH ratio from 0 to 9. Cross-sectional hydrogen content and mass density profiles of the films were defined by neutron and X-ray reflectivity measurements, and the results were compared with that from ERDA analysis. And O/C atomic ratio of the oxide layer of the film surface was also analyzed using XPS. From the neutron and X-ray reflectivity analysis, hydrogen content and mass density in the DLC film increased with film depth from the surface, and average hydrogen content showed more than 30 % in all films. By combining with XPS results, it is clarified that hydrogen content in the surface layer was lower than that in bulk layer.