Pseudotunnel magnetoresistance in twisted van der Waals FeGeTe homojunctions

Obata, Reiji*; Saito, Eiji; Kikkawa, Takashi; 13 of others*

Advanced Materials, 37(8), p.2411459_1 - 2411459_11, 2025/02

https://doi.org/10.1002/adma.202411459

Quantitative evaluation of irradiated ductility degradation using the indentation technique combined with numerical experiments

Wakui, Takashi; Saito, Shigeru; Futakawa, Masatoshi

Materials, 17(23), p.5925_1 - 5925_14, 2024/12

https://doi.org/10.3390/ma17235925

The ductile properties of irradiated materials are one of the important indicators related to their structural integrity. Indentation tests are used for evaluating the ductile properties easily and rapidly. Constants in the material constitutive equation were identified via inverse analysis using the Kalman filter, such that the numerical experimental results reproduced the indentation test results. Numerical tensile experiments were conducted using stress-strain curves with the identified constants to obtain nominal stress-strain curves. Furthermore, two methods were proposed for evaluating the total elongation. Evaluated minimum total elongation was 10 %. The evaluation results of ion-irradiated materials were similar to the tensile test results of irradiated materials.

Enhanced magnetism derived from pore-edge spins in thin FeGeTe nanomeshes

Obata, Reiji*; Kikkawa, Takashi*; Saito, Eiji; 7 of others*

Nanotechnology, 35(47), p.475601_1 - 475601_9, 2024/11

https://doi.org/10.1088/1361-6528/ad6fa2

Differential pressure rise event for filters of HTTR primary helium gas circulators, 2; Investigation of filter deposits and recurrence prevention measures

Nemoto, Takahiro; Fujiwara, Yusuke; Arakawa, Ryoki; Choyama, Yuya; Nagasumi, Satoru; Hasegawa, Toshinari; Yokoyama, Keisuke; Watanabe, Masashi; Onishi, Takashi; Kawamoto, Taiki; et al.

JAEA-Technology 2024-003, 17 Pages, 2024/06

JAEA-Technology-2024-003.pdf:1.91MB

In order to investigate the cause of the increase in differential pressure in the primary helium circulator filter that occurred during the RS-14 cycle, a clogged filter was investigated. As a result of the investigation, deposits caused by silicone oil were confirmed on the surface of the filter element. These results revealed that the cause of filter clogging was silicone oil mixed into the primary system due to performance deterioration of the charcoal filter in the gas circulator of primary helium purification system. As a measure to prevent the recurrence of this event, in addition to the conventional management based on operating hours for replacing of charcoal filter in the gas circulator of primary helium purification system, we have established a new replacement plan for every three years.

Understanding spin currents from magnon dispersion and polarization; Spin-Seebeck effect and neutron scattering study on TbFeO

Kawamoto, Yo*; Kikkawa, Takashi; Saito, Eiji; 9 of others*

Applied Physics Letters, 124(13), p.132406_1 - 132406_7, 2024/03

https://doi.org/10.1063/5.0197831

Development of a non-destructive depth-selective quantification method for sub-percent carbon contents in steel using negative muon lifetime analysis

Ninomiya, Kazuhiko*; Kubo, Kenya*; Inagaki, Makoto*; Yoshida, Go*; Chiu, I.-H.; Kudo, Takuto*; Asari, Shunsuke*; Sentoku, Sawako*; Takeshita, Soshi*; Shimomura, Koichiro*; et al.

Scientific Reports (Internet), 14, p.1797_1 - 1797_8, 2024/01

https://doi.org/10.1038/s41598-024-52255-5

The amount of C in steel, which is critical in determining its properties, is strongly influenced by steel production technology. We propose a novel method of quantifying the bulk C content in steel non-destructively using muons. This revolutionary method may be used not only in the quality control of steel in production, but also in analyzing precious steel archaeological artifacts. A negatively charged muon forms an atomic system owing to its negative charge, and is finally absorbed into the nucleus or decays to an electron. The lifetimes of muons differ significantly, depending on whether they are trapped by Fe or C atoms, and identifying the elemental content at the muon stoppage position is possible via muon lifetime measurements. The relationship between the muon capture probabilities of C/Fe and the elemental content of C exhibits a good linearity, and the C content in the steel may be quantitatively determined via muon lifetime measurements. Furthermore, by controlling the incident energies of the muons, they may be stopped in each layer of a stacked sample consisting of three types of steel plates with thicknesses of 0.5 mm, and we successfully determined the C contents in the range 0.20 - 1.03 wt% depth-selectively, without sample destruction.

Gate-tunable resistance drops related to local superconducting gaps in thin TaS layers on SrTiO substrates

Kosugi, Mioko*; Saito, Eiji; Kikkawa, Takashi*; 11 of others*

APL Materials (Internet), 11(8), p.081106_1 - 081106_6, 2023/08

https://doi.org/10.1063/5.0147818

Intruder configurations in Ne at the transition into the island of inversion; Detailed structure study of Ne

Wang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.

Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08

https://doi.org/10.1016/j.physletb.2023.138038

Detailed -ray spectroscopy of the exotic neon isotope Ne has been performed using the one-neutron removal reaction from Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.

Spin Seebeck effect; Sensitive probe for elementary excitation, spin correlation, transport, magnetic order, and domains in solids

Kikkawa, Takashi*; Saito, Eiji

Annual Review of Condensed Matter Physics, 14, p.129 - 151, 2023/03

https://doi.org/10.1146/annurev-conmatphys-040721-014957

Mechanism of paramagnetic spin Seebeck effect

Oyanagi, Koichi*; Takahashi, Saburo*; Kikkawa, Takashi*; Saito, Eiji

Physical Review B, 107(1), p.014423_1 - 014423_8, 2023/01

https://doi.org/10.1103/PhysRevB.107.014423