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Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Opletal, P.; Tokiwa, Yoshifumi; Haga, Yoshinori; Kitagawa, Shunsaku*; Ishida, Kenji*; Aoki, Dai*; Knebel, G.*; et al.
Physical Review Letters, 131(22), p.226503_1 - 226503_7, 2023/12
Times Cited Count：0 Percentile：0(Physics, Multidisciplinary)
10
W/cm
Skobelev, I. Yu.*; Ryazantsev, S. N.*; Kulikov, R. K.*; Sedov, M. V.*; Filippov, E. D.*; Pikuz, S. A.*; Asai, Takafumi*; Kanasaki, Masato*; Yamauchi, Tomoya*; Jinno, Satoshi; et al.
Photonics (Internet), 10(11), p.1250_1 - 1250_11, 2023/11
Times Cited Count：0 Percentile：0(Optics)It is challenging to clearly distinguish the impacts of the optical field and collisional ionization in the evolution of the charge state of a plasma produced when matter interacts with high-intensity laser pulses. In this work, time-dependent calculations of plasma kinetics are used to show that it is possible only when low-density gaseous targets with sufficiently small clusters are used. In the case of Ar plasma, the upper limit of the cluster radius was estimated to be 
m.
RhGa explored by 
Ga nuclear quadrupole resonanceYamamoto, Shingo*; Fujii, Takuto*; Luther, S.*; Yasuoka, Hiroshi*; Sakai, Hironori; B
rtl, F.*; Ranjith, K. M.*; Rosner, H.*; Wosnitza, J.*; Strydom, A. M.*; et al.
Physical Review B, 106(11), p.115125_1 - 115125_5, 2022/09
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)We have studied the microscopic magnetic properties, the nature of the 130 K phase transition, and the ground state in the recently synthesized compound CeRhGa by use of Ga nuclear quadrupole resonance (NQR). The NQR spectra clearly show an unusual phase transition at 
K, yielding a splitting of the high-temperature single NQR line into two well-resolved NQR lines, providing evidence for two crystallographically inequivalent Ga sites. The NQR frequencies are in good agreement with fully relativistic calculations of the band structure. Our NQR results indicate the absence of magnetic or charge order down to 0.3 K. The temperature dependence of the spin-lattice relaxation rate 
shows three distinct regimes, with onset temperatures at 
and 2 K. The temperature-independent , observed between and 2 K, crosses over to a Korringa process, 
, below 
2 K, which evidences a rare two-ion Kondo scenario: The system evolves into a dense Kondo coherent state below 2.0 and 0.8 K probed by the two different Ga sites.
; 
In NQR/NMR and 
Co NMR studySakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Zhu, J.-X.*; Ronning, F.*; Thompson, J. D.*; Ramakrishna, S. K.*; Reyes, A. P.*; Suzuki, Kohei*; Oshima, Yoshiki*; et al.
Physical Review B, 104(8), p.085106_1 - 085106_12, 2021/08
Times Cited Count：3 Percentile：27.71(Materials Science, Multidisciplinary)Antiferromagnetism in a prototypical quantum critical metal CeCoIn is known to be induced by slight substitutions of non-magnetic Zn atoms for In. In nominally 7% Zn substituted CeCoIn, an antiferromagnetic (AFM) state coexists with heavy fermion superconductivity. Heterogeneity of the electronic states is investigated in Zn doped CeCoIn by means of nuclear quadrupole and magnetic resonances (NQR and NMR). Site-dependent NQR relaxation rates indicate that the AFM state is locally nucleated around Zn substituents in the matrix of a heavy fermion state, and percolates through the bulk at the AFM transition temperature 
. At lower temperatures, an anisotropic superconducting (SC) gap below the SC transition temperature 
, and the SC state permeates through the AFM regions via a SC proximity effect. Applying an external magnetic field induces a spin-flop transition near 5 T, reducing the volume of the AFM regions. Consequently, a short ranged inhomogeneous AFM state survives and coexists with a paramagnetic Fermi liquid state at high fields.
-Al
O
(0001)Entani, Shiro*; Honda, Mitsunori; Naramoto, Hiroshi*; Li, S.*; Sakai, Seiji*
Surface Science, 704, p.121749_1 - 121749_6, 2021/02
Times Cited Count：4 Percentile：33.7(Chemistry, Physical)Graphene is expected to be one of the most promising materials for nanoelectronics and spintronics. In most graphene-based devices, the graphene channel is placed on insulating substrates. Therefore, the study of inter-facial interactions between graphene and the insulator surface is of critical importance. In this study, the vertical arrangement of graphene which is transferred on -AlO(0001) has been studied by normal incidence X-ray standing wave (NIXSW) technique. The analysis of the NIXSW profile reveals that the graphene layer is located at 3.57 (
) above the -AlO(0001) surface, which is larger than the interlayer distance of graphite at 3.356 (). Micro- Raman spectroscopy shows that the transferred graphene has a limited spatial distribution of hole concentration. The present study shows that transferred graphene on the sapphire substrate followed by vacuum-annealing has an atomically flat surface free from residual contaminations such as organic compounds and there occurs the hole-doping in graphene.
F from 
O
?Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri, A.*; Hwang, S. H.*; et al.
Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05
Times Cited Count：14 Percentile：74.18(Physics, Multidisciplinary)The structure of a neutron-rich F nucleus is investigated by a quasifree (
) knockout reaction. The sum of spectroscopic factors of 
orbital is found to be 1.0 
0.3. The result shows that the O core of F nucleus significantly differs from a free O nucleus, and the core consists of 35% O
, and 65% excited O. The result shows that the O core of F nucleus significantly differs from a free O nucleus. The result may infer that the addition of the 
proton considerably changes the neutron structure in F from that in O, which could be a possible mechanism responsible for the oxygen dripline anomaly.
S nuclear magnetic resonance spectra of uranium disulfide 
-USSakai, Hironori; Tokunaga, Yo; Haga, Yoshinori; Kambe, Shinsaku; Ramakrishna, S. K.*; Reyes, A. P.*; Rosa, P. F. S.*; Ronning, F.*; Thompson, J. D.*; Fisk, Z.*; et al.
JPS Conference Proceedings (Internet), 30, p.011169_1 - 011169_6, 2020/03
Uranium disulfide -US showing a semimetal-to-semiconductor crossover has been investigated by the nuclear magnetic resonance (NMR) technique for S nuclei with the nuclear spin of 
. Since the natural concentration 0.76% of NMR active S nuclei is too dilute, the isotopic enrichment to 50% has been carried out for the single crystal growth. The S NMR spectra have been successfully obtained using a single crystal of -US with external fields along the crystallographic 
axis. The S sites assignments have been made based on these NMR spectra.
Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati
, M.*; Sakai, Hironori; Kambe, Shinsaku; Hattori, Taisuke; et al.
JPS Conference Proceedings (Internet), 30, p.011037_1 - 011037_6, 2020/03
The field-angular dependence of Co-NMR spin-lattice relaxation rate has been measured for a 10% Co-doped single crystal of URhGe. The experiment revealed that spin fluctuations in ferromagnetic (FM) state of URhGe are robust against magnetic field below about 4 T, applied along any direction in the 
crystal plane. This is in clear contrast with the sister compound UCoGe, in which FM spin fluctuations are rapidly suppressed by a tiny applied field along the axis. We show that such a difference in the character of the spin fluctuations is reflected in their two distinct phase diagrams for the upper critical field 
, providing further support to the mechanism of superconductivity mediated by spin fluctuations in these materials.
Tanaka, Taiki*; Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Boll, R. A.*; Brewer, N. T.*; Van Cleve, S.*; Dean, D. J.*; Ishizawa, Satoshi*; et al.
Physical Review Letters, 124(5), p.052502_1 - 052502_6, 2020/02
Times Cited Count：19 Percentile：81.08(Physics, Multidisciplinary)
; Pulsed-field NMR study on single crystals up to 56 TTokunaga, Yo; Orlova, A.*; Bruyant, N.*; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Higa, Nonoka; et al.
Physical Review B, 99(8), p.085142_1 - 085142_5, 2019/02
Times Cited Count：6 Percentile：27.67(Materials Science, Multidisciplinary)The heavy-fermion antiferromagnet CeIn exhibits a field-induced anomaly associated with Fermi surface reconstruction at 
45 T, well below the antiferromagnetic (AFM) critical field that exceeds 60 T. In order to explore the origin of this anomaly, we have measured In NMR spectra in pulsed magnetic fields up to 56 T using high-quality single crystals. To within experimental resolution, we do not detect any change in the NMR spectra that could suggest a modification in either the character of the hyperfine field or the electric field gradient at In sites through 
. This strongly suggests that the 45 T anomaly cannot be simply ascribed to a field-induced change in the magnetic structure of the AFM state.
Pu nuclear magnetic resonance in the candidate topological insulator PuB
Dioguardi, A. P.*; Yasuoka, Hiroshi*; Thomas, S. M.*; Sakai, Hironori; Cary, S. K.*; Kozimor, S. A.*; Albrecht-Schmitt, T. E.*; Choi, H. C.*; Zhu, J.-X.*; Thompson, J. D.*; et al.
Physical Review B, 99(3), p.035104_1 - 035104_6, 2019/01
Times Cited Count：8 Percentile：37.59(Materials Science, Multidisciplinary)We present a detailed nuclear magnetic resonance (NMR) study of Pu in bulk and powdered single-crystal plutonium tetraboride (PuB), which has recently been investigated as a potential correlated topological insulator. The Pu NMR spectra are consistent with axial symmetry of the shift tensor showing for the first time that Pu NMR can be observed in an anisotropic environment and up to room temperature. The temperature dependence of the Pu shift, combined with a relatively long spin-lattice relaxation time (
), indicate that PuB adopts a nonmagnetic state with gaplike behavior consistent with our density functional theory calculations. The temperature dependencies of the NMR Knight shift and 
imply bulk gaplike behavior confirming that PuB is a good candidate topological insulator.
Entani, Shiro*; Honda, Mitsunori; Shimoyama, Iwao; Li, S.*; Naramoto, Hiroshi*; Yaita, Tsuyoshi; Sakai, Seiji*
Japanese Journal of Applied Physics, 57(4S), p.04FP04_1 - 04FP04_4, 2018/04
Times Cited Count：3 Percentile：14.78(Physics, Applied)Sakai, Takaaki; Ren, L.*; Tsige-Tamirat, H.*; Vasile, A.*; Kang, S.-H.*; Ashurko, Y.*; Fanning, T.*
Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 7 Pages, 2016/06
Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Sakai, Hironori; Hattori, Taisuke; Kambe, Shinsaku; et al.
Physical Review B, 93(20), p.201112_1 - 201112_5, 2016/05
Times Cited Count：14 Percentile：54.92(Materials Science, Multidisciplinary)The ferromagnetic superconductor URhGe has been known to exhibit an extremely large enhancement of the upper critical field when the field is confined and rotated in the (
) crystal plane. Our high-field Co NMR measurements on 10% Co-doped URhGe up to 30 T prove that this unconventional behavior of the superconductivity (SC) is associated with a strong anisotropy of field-dependent quantum fluctuations near a tricritical point. These fluctuations are rapidly suppressed by the field component along the axis, while being unaffected by any field component along the 
axis. The observed close interplay between the SC and quantum fluctuations strongly supports a pairing mechanism mediated by these fluctuations in URhGe.
Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Sakai, Hironori; Kambe, Shinsaku; Hattori, Taisuke; et al.
Journal of Physics; Conference Series, 683(1), p.012010_1 - 012010_6, 2016/02
Times Cited Count：0 Percentile：0.03(Materials Science, Multidisciplinary)Metamagnetism is in itself quite interesting phenomena, especially in a system with itinerant f-electrons. Unconventional states observed in the vicinity of the metamagnetic transition have been the subject of a number of recent publications. The object of this study is to elucidate the interplay between superconductivity and metamagnetism in URhGe. The nature of the metamagnetism becomes particularly important in ferromagnetic superconductors URhGe and UCoGe, since it is likely related to the pairing mechanism for their unconventional superconductivity. Here we report the result of our Co-NMR study on URh
Co
Ge and discuss the origin of the field induced superconducting phenomenon observed in high fields around 12 T.
RuO
Josephson junctionsKaneyasu, Hirono*; Etter, S. B.*; Sakai, Toru; Sigrist, M.*
Physical Review B, 92(13), p.134515_1 - 134515_5, 2015/10
Times Cited Count：4 Percentile：14.69(Materials Science, Multidisciplinary)The evolution of the 3-Kelvin superconductivity phase at the interface between SrRuO and Ru-metal inclusions is discussed for Pb-Ru-SrRuO contacts. Using the Ginzburg-Landau model, the influence of proximity-induced superconductivity in Ru on the topology of the 3-K phase is analysed. Because the s-wave order parameter in Ru favors a 3-K state of trivial topology, the onset temperature of the phase with a nontrivial topology is essentially reduced to the bulk transition temperature.
Ajimura, Shuhei*; Bezerra, T. J. C.*; Chauveau, E.*; Enomoto, T.*; Furuta, Hisataka*; Harada, Masahide; Hasegawa, Shoichi; Hiraiwa, T.*; Igarashi, Yoichi*; Iwai, Eito*; et al.
Progress of Theoretical and Experimental Physics (Internet), 2015(6), p.063C01_1 - 063C01_19, 2015/06
Times Cited Count：6 Percentile：45.25(Physics, Multidisciplinary)The J-PARC E56 experiment aims to search for sterile neutrinos at the J-PARC Materials and Life Science Experimental Facility (MLF). In order to examine the feasibility of the experiment, we measured the background rates of different detector candidate sites, which are located at the third floor of the MLF, using a detector consisting of plastic scintillators with a fiducial mass of 500 kg. The gammas and neutrons induced by the beam as well as the backgrounds from the cosmic rays were measured, and the results are described in this article.
Co NMR in URh
Co
GeTokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Sakai, Hironori; Kambe, Shinsaku; Araki, Shingo*
Physical Review Letters, 114(21), p.216401_1 - 216401_5, 2015/05
Times Cited Count：51 Percentile：89.51(Physics, Multidisciplinary)Our measurements of the Co NMR spin-spin relaxation in URhCoGe reveal a divergence of electronic spin fluctuations in the vicinity of the field-induced quantum critical point at 
T, around which reentrant superconductivity (RSC) occurs in the ferromagnetic heavy fermion compound URhGe. We show that critical fluctuations develop in the same limited region near the field 
as that where RSC is observed. This strongly suggests these quantum fluctuations as the pairing glue responsible for the RSC. The fluctuations observed are characteristic of a tricritical point.
by diffuse neutron scattering measurementSakuma, Takashi*; Makhsun*; Sakai, Ryutaro*; Xianglian*; Takahashi, Haruyuki*; Basar, K.*; Igawa, Naoki; Danilkin, S. A.*
AIP Conference Proceedings 1656, p.020002_1 - 020002_4, 2015/04
Times Cited Count：2 Percentile：63.4(Physics, Applied)Diffuse neutron scattering measurement on BaF crystals was performed at 10 K and 295 K. Oscillatory form in the diffuse scattering intensity of BaF was observed at 295 K. The correlation effects among thermal displacements of F-F atoms were obtained from the analysis of oscillatory diffuse scattering intensity. From the values of correlation effects and Debye-Waller temperature parameters, force constants among the first and second nearest neighboring atoms of BaF, were determined to be 4.40 and 2.30 eV/
at 295 K, respectively
Kuzubov, A. A.*; Kovaleva, E. A.*; Avramov, P. V.*; Kuklin, A. V.*; Mikhaleva, N. S.*; Tomilin, F. N.*; Sakai, Seiji; Entani, Shiro; Matsumoto, Yoshihiro*; Naramoto, Hiroshi*
Journal of Applied Physics, 116(8), p.084309_1 - 084309_4, 2014/08
Times Cited Count：9 Percentile：38.16(Physics, Applied)