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Shimizu, Yusei*; Kittaka, Shunichiro*; Kono, Yohei*; Nakamura, Shota*; Haga, Yoshinori; Yamamoto, Etsuji; Machida, Kazushige*; Amitsuka, Hiroshi*; Sakakibara, Toshiro*
Physical Review B, 112(24), p.245157_1 - 245157_10, 2025/12
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)
Be nuclear magnetic resonance in UBe; Itinerant-localized duality and possible Fermi surface reconstruction at high magnetic fieldMatsuki, Rintaro*; Minami, Shoko*; Kotegawa, Hisashi*; Harima, Hisatomo*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*; To, Hideki*
Journal of the Physical Society of Japan, 94(12), p.124702_1 - 124702_8, 2025/11
Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)
Tokiwa, Yoshifumi; Opletal, P.; Sakai, Hironori; Kubo, Katsunori; Kambe, Shinsaku; Yamamoto, Etsuji; Kimata, Motoi; Awaji, Satoshi*; Sasaki, Takahiko*; Aoki, Dai*; et al.
Physical Review Letters, 135(13), p.136502_1 - 136502_6, 2025/09
Times Cited Count：1 Percentile：58.26(Physics, Multidisciplinary)We investigate the effect of easy-axis metamagnetic crossover on superconductivity in UTe along the 
-axis through measurements of AC susceptibility, magnetization, and the magnetocaloric effect. In ultra-clean single crystals, we identify a field-induced phase transition within the superconducting state at 5.6 T, driven by metamagnetism. This transition leads to a high-field superconducting state, significantly increasing the upper critical field to 12 T. A sudden increase in entropy at the transition suggests a self-reconstruction of the order parameter, enabling multi-component superconducting states to adapt to external perturbations.
Kokubun, Yuji; Hosomi, Kenji; Seya, Natsumi; Nagaoka, Mika; Inoue, Kazumi; Koike, Yuko; Hasegawa, Ryo; Kubota, Tomohiro; Hirao, Moe; Iizawa, Shogo; et al.
JAEA-Review 2024-053, 116 Pages, 2025/03
JAEA-Review-2024-053.pdf:3.26MB
Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution prevention act, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2023. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.
Nii, Yoichi*; Yamamoto, Kei; Kanno, Masaki*; Maekawa, Sadamichi*; Onose, Yoshinori*
Physical Review Letters, 134(2), p.027001_1 - 027001_5, 2025/01
Times Cited Count：5 Percentile：93.21(Physics, Multidisciplinary)Tokiwa, Yoshifumi; Opletal, P.; Sakai, Hironori; Kambe, Shinsaku; Yamamoto, Etsuji; Kimata, Motoi*; Awaji, Satoshi*; Sasaki, Takahiko*; Aoki, Dai*; Haga, Yoshinori; et al.
Physical Review B, 109(14), p.L140502_1 - L140502_6, 2024/04
Times Cited Count：7 Percentile：74.71(Materials Science, Multidisciplinary)The normal-conducting state of the superconductor UTe is studied by entropy analysis for magnetic fields along the 
-axis, obtained from magnetization using the relation 
. We observe a strong increase in entropy with magnetic field due to metamagnetic fluctuations (spatially uniform, 
). The field dependence is well described by the Hertz-Millis-Moriya theory for quantum criticality of itinerant metamagnetism. Notably, the lower bound of the quantum-critical region coincides well with the position of the minimum in the superconducting transition temperature 
. Hence, our results suggest that fluctuations reinforce the superconductivity.
Kokubun, Yuji; Nakada, Akira; Seya, Natsumi; Nagaoka, Mika; Koike, Yuko; Kubota, Tomohiro; Hirao, Moe; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; et al.
JAEA-Review 2023-052, 118 Pages, 2024/03
JAEA-Review-2023-052.pdf:3.67MB
Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2022. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.
Tokiwa, Yoshifumi; Sakai, Hironori; Kambe, Shinsaku; Opletal, P.; Yamamoto, Etsuji; Kimata, Motoi*; Awaji, Satoshi*; Sasaki, Takahiko*; Yanase, Yoichi*; Haga, Yoshinori; et al.
Physical Review B, 108(14), p.144502_1 - 144502_5, 2023/10
Times Cited Count：9 Percentile：64.61(Materials Science, Multidisciplinary)The vortex dynamics in the spin-triplet superconductor, UTe, are studied by measuring the DC electrical resistivity with currents along the -axis under magnetic fields along the -axis. Surprisingly, we have discovered an island region of low critical current deep inside the superconducting (SC) state, well below the SC upper critical field, attributed to a weakening of vortex pinning. Notably, this region coincides with the recently proposed intermediate-field SC state. We discuss the possibility of nonsingular vortices in the intermediate state, where SC order parameter does not vanish entirely in the vortex cores due to the mixing of multiple SC components.
Kawasaki, Ikuto; Takeuchi, Kazuharu*; Fujimori, Shinichi; Takeda, Yukiharu; Yamagami, Hiroshi; Yamamoto, Etsuji; Haga, Yoshinori
Physical Review B, 108(16), p.165127_1 - 165127_9, 2023/10
Times Cited Count：2 Percentile：16.78(Materials Science, Multidisciplinary)Takeda, Yukiharu; Posp
il, J.*; Yamagami, Hiroshi; Yamamoto, Etsuji; Haga, Yoshinori
Physical Review B, 108(8), p.085129_1 - 085129_10, 2023/08
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)
Te
Opletal, P.; Sakai, Hironori; Haga, Yoshinori; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Kambe, Shinsaku; Tokunaga, Yo
Journal of the Physical Society of Japan, 92(3), p.034704_1 - 034704_5, 2023/03
Times Cited Count：4 Percentile：49.37(Physics, Multidisciplinary)We investigate the physical properties of a single crystal of uranium telluride UTe. We have confirmed that UTe crystallizes in the hexagonal structure with three nonequivalent crystallographic uranium sites. The paramagnetic moments are estimated to be approximately 1 
per the uranium site, assuming a uniform moment on all the sites. A ferromagnetic phase transition occurs at 
= 48 K, where the in-plane magnetization increases sharply, whereas the out of-plane component does not increase significantly. With decreasing temperature further below under field-cooling conditions, the out-of-plane component increases rapidly around T
= 26 K. In contrast, the in-plane component hardly changes at T. Specific heat measurement indicates no 
-type anomaly around T, so this is a cross-over suggesting a reorientation of the ordering moments or successive magnetic ordering on the part of the multiple uranium sites.
by molten salt flux methodSakai, Hironori; Opletal, P.; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Tokunaga, Yo; Kambe, Shinsaku; Haga, Yoshinori
Physical Review Materials (Internet), 6(7), p.073401_1 - 073401_10, 2022/07
Times Cited Count：75 Percentile：96.38(Materials Science, Multidisciplinary)The molten salt flux method is applied as a new synthetic route for the single crystals of the spin-triplet superconductor UTe. The single crystals under an optimized growth condition with excess uranium exhibit a superconducting transition at 
K, which is the highest 
reported for this compound. The obtained crystals show a remarkably large residual resistivity ratio with respect to the room temperature value and a small residual electronic contribution in specific heat well below . These results indicate that the increase of in UTe can be achieved by reducing the disorder associated with uranium vacancies. The excess uranium in the molten salt acts as a reducing agent, preventing tetravalent uranium from becoming pentavalent and suppressing creation of uranium vacancies. At the same time, the relatively low growth temperature can suppress Te volatilization.
Haga, Yoshinori; Opletal, P.; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Tokunaga, Yo; Kambe, Shinsaku; Sakai, Hironori
Journal of Physics; Condensed Matter, 34(17), p.175601_1 - 175601_7, 2022/04
Times Cited Count：37 Percentile：86.97(Physics, Condensed Matter)Al; Impact of the U 
states on the electronic structure of UPdAlFujimori, Shinichi; Takeda, Yukiharu; Yamagami, Hiroshi; Pospil, J.*; Yamamoto, Etsuji; Haga, Yoshinori
Physical Review B, 105(11), p.115128_1 - 115128_6, 2022/03
Times Cited Count：1 Percentile：5.09(Materials Science, Multidisciplinary)Pt
Ga
Matsumoto, Yuji*; Haga, Yoshinori; Yamamoto, Etsuji; Takeuchi, Tetsuya*; Miyake, Atsushi*; Tokunaga, Masashi*
Journal of the Physical Society of Japan, 90(7), p.074707_1 - 074707_6, 2021/07
Times Cited Count：2 Percentile：19.30(Physics, Multidisciplinary)Noma, Yuichiro*; Kotegawa, Hisashi*; Kubo, Tetsuro*; To, Hideki*; Harima, Hisatomo*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*; Ito, Kohei*; Nakamura, Ai*; et al.
Journal of the Physical Society of Japan, 90(7), p.073707_1 - 073707_5, 2021/07
Times Cited Count：2 Percentile：19.30(Physics, Multidisciplinary)Si in paramagnetic phase; Three-dimensional angle resolved photoelectron spectroscopy studyFujimori, Shinichi; Takeda, Yukiharu; Yamagami, Hiroshi; Yamamoto, Etsuji; Haga, Yoshinori
Electronic Structure (Internet), 3(2), p.024008_1 - 024008_8, 2021/06
Rh
Ge ferromagnets in magnetic field along the axisPospil, J.*; Haga, Yoshinori; Miyake, Atsushi*; Kambe, Shinsaku; Tokunaga, Yo; Tokunaga, Masashi*; Yamamoto, Etsuji; Proschek, P.*; Voln
, J.*; Sechovsk, V.*
Physical Review B, 102(2), p.024442_1 - 024442_13, 2020/07
Times Cited Count：7 Percentile：31.16(Materials Science, Multidisciplinary)
-electron state of the heavy fermion superconductor NpPd
Al and the isostructural familyMetoki, Naoto; Aczel, A. A.*; Aoki, Dai*; Chi, S.*; Fernandez-Baca, J. A.*; Griveau, J.-C.*; Hagihara, Masato*; Hong, T.*; Haga, Yoshinori; Ikeuchi, Kazuhiko*; et al.
JPS Conference Proceedings (Internet), 30, p.011123_1 - 011123_6, 2020/03
Rare earths (4) and actinides (5) provide variety of interesting states realized with competing interactions between the increasing number of electrons. Since crystal field splitting of many-body electron system is smaller than the bandwidth, (1) high resolution experiments are needed, (2) essentially no clear spectrum with well defined peaks is expected in itinerant Ce and U compounds, and (3) Np and Pu is strictly regulated. Therefore, systematic research on magnetic excitations by neutron scattering experiments of localized compounds and rare earth iso-structural reference is useful. We describe the electron states of heavy electron compounds NpPdAl and actinide and rare earth based iso-structural family.
PtAlHaga, Yoshinori; Sugai, Takashi*; Matsumoto, Yuji*; Yamamoto, Etsuji
JPS Conference Proceedings (Internet), 29, p.013003_1 - 013003_5, 2020/02
