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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.
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.
Ta quadrupole resonanceYasuoka, Hiroshi; Kubo, Tetsuro*; Kishimoto, Yasuki*; Kasinathan, D.*; Schmidt, M.*; Yan, B.*; Zhang, Y.*; To, Hideki*; Felser, C.*; Mackenzie, A. P.*; et al.
Physical Review Letters, 118(23), p.236403_1 - 236403_6, 2017/07
Times Cited Count：29 Percentile：82.8(Physics, Multidisciplinary)The Ta quadrupole resonance (NQR) technique has been utilized to investigate the microscopic magnetic properties of the Weyl semi-metal TaP. We found three zero-field NQR signals associated with the transition between the quadrupole split levels for Ta with 
=7/2 nuclear spin. A quadrupole coupling constant, 
= 19.250 MHz, and an asymmetric parameter of the electric field gradient, 
= 0.423 were extracted, in good agreement with the theoretical calculations. In order to examine the magnetic excitations, the temperature dependence of the spin lattice relaxation rate (1/
) has been measured for the 
-line (
transition). We found that there exist two regimes with quite different relaxation processes. Above 
*
K, a pronounced (
behavior was found which is attributed to the magnetic excitations at the Weyl nodes with temperature dependent orbital hyperfine coupling. Below *, the relaxation is mainly governed by Korringa process with (1/) = constant, while we have to include a 
type dependence in order to reproduce our experimental data. We show that Ta-NQR is a novel probe for the bulk Weyl fermions and their excitations.
; NQR relaxation ratesSakai, Hironori; Ronning, F.*; Hattori, Takanori; Tokunaga, Yo; Kambe, Shinsaku; Zhu, J.-X.*; Wakeham, N.*; Yasuoka, Hiroshi; Bauer, E. D.*; Thompson, J. D.*
Journal of Physics; Conference Series, 807(3), p.032001_1 - 032001_6, 2017/04
Times Cited Count：3 Percentile：68.62(Physics, Condensed Matter)We have used nuclear quadrupole resonance (NQR) to probe microscopically the response of a prototypical quantum critical metal CeCoIn to substitutions of small amounts of Cd for In. Approximately half of the Cd substituents induce local Ce moments in their close proximity, as observed by site-dependent longitudinal nuclear spin relaxation rates . To reaffirm that localized 
moments are induced around the Cd substituents, we find a Gaussian spin-echo decay rate 
of transverse nuclear spin relaxation. Further, 
for the NQR subpeak is found to be proportional to temperatures, again indicating local moments fluctuations around the Cd substituents, while that for the NQR main peak shows a 
-dependence. The latter temperature dependence is close to 0.75 in pure CeCoIn and indicates that the bulk electronic state is located close to a two dimensional quantum critical instability.
Si NMR studyYasuoka, Hiroshi; Motoya, Kiyoichiro*; Majumder, M.*; Witt, S.*; Kerllner, C.*; Baenitz, M.*
Journal of the Physical Society of Japan, 85(7), p.073701_1 - 073701_4, 2016/07
Times Cited Count：3 Percentile：27.79(Physics, Multidisciplinary)Sakai, Hironori; Ronning, F.*; Zhu, J.-X.*; Wakeham, N.*; Yasuoka, Hiroshi; Tokunaga, Yo; Kambe, Shinsaku; Bauer, E. D.*; Thompson, J. D.*
Physical Review B, 92(12), p.121105_1 - 121105_5, 2015/09
Times Cited Count：19 Percentile：62.1(Materials Science, Multidisciplinary)Chemical substitutions are used commonly to tune a magnetic transition to zero temperature, but the resulting non-Fermi liquid (NFL) behavior is non-universal. We have used nuclear quadrupole resonance (NQR) to probe microscopically the response of a prototypical quantum-critical metal CeCoIn to substitutions of small amounts of Sn and Cd for In. These substituents induce very different local electronic environments as observed by site dependent spin lattice relaxation rates that influence the NFL behavior. The effects found here illustrate the need for care in interpreting NFL properties determined by macroscopic measurements.
Chudo, Hiroyuki; Ono, Masao; Harii, Kazuya; Matsuo, Mamoru; Ieda, Junichi; Haruki, Rie*; Okayasu, Satoru; Maekawa, Sadamichi; Yasuoka, Hiroshi; Saito, Eiji
Applied Physics Express, 7(6), p.063004_1 - 063004_4, 2014/06
Times Cited Count：44 Percentile：84.37(Physics, Applied)A magnetic field is predicted to emerge on a particle in a rotating body even if the body is electrically neutral. This emergent field is called a Barnett field. We show that nuclear magnetic resonance (NMR) enables direct measurement of the Barnett field in solids. We rotated both a sample and an NMR coil synchronously at high speed and found an NMR shift whose sing reflects that of the nuclear magnetic moments. This result provides direct evidence of the Barnett field. The use of NMR for Barnett field measurement enables the unknown signs of nuclear magnetic moments in solids to be determined.
explored by nuclear quadrupole resonanceKoutroulakis, G.*; Yasuoka, Hiroshi; Chudo, Hiroyuki; Tobash, P. H.*; Mitchell, J. N.*; Bauer, E. D.*; Thompson, J. D.*
New Journal of Physics (Internet), 16, p.053019_1 - 053019_12, 2014/05
Times Cited Count：6 Percentile：44.89(Physics, Multidisciplinary)We report 
In nuclear quadrupolar resonance (NQR) measurements on the heavy-fermion superconductor PuCoIn, in the temperature range 0.29 K 
75 K. The NQR parameters for the two crystallographically inequivalent In sites are determined, and their temperature dependence is investigated. A linear shift of the quadrupolar frequency with lowering temperature below the critical value 
is revealed, in agreement with the prediction for composite pairing. The nuclear spin-lattice relaxation rate 
clearly signals a superconducting (SC) phase transition at 
2.3 K, with strong spin fluctuations, mostly in-plane, dominating the relaxation process in the normal state near to . Analysis of the 
data in the SC state suggests that PuCoIn is a strong-coupling 
-wave superconductor.
explored using In nuclear quadrupole resonanceChudo, Hiroyuki; Koutroulakis, G.*; Yasuoka, Hiroshi; Bauer, E. D.*; Tobash, P. H.*; Mitchell, J. N.*; Thompson, J. D.*
Journal of Physics; Condensed Matter, 26(3), p.036001_1 - 036001_5, 2014/01
Times Cited Count：5 Percentile：23.98(Physics, Condensed Matter)The results of In nuclear quadrupole resonance (NQR) measurements on PuIn are reported. Three of the four NQR lines of In expected for nuclear spin =9/2 are observed. The equal spacing of these lines at 20 K yields the NQR frequency of 
=10.45 MHz, and the asymmetry parameter of the electric field gradient, =0. The NQR line profile and the nuclear spin-lattice relaxation rate display an abrupt change at 14 K, which is associated with the onset of long-range antiferromagnetic order. The temperature dependences of the staggered magnetization 
, extracted from the NQR spectra, and below 
=14 K are well explained by the self-consistent renormalization (SCR) theory for spin fluctuations. In addition, scaling between and 
is also consistent with the predictions of SCR theory, providing further evidence that PuIn is a weak itinerant antiferromagnet in which spin fluctuations around the antiferromagnetic wave vector play a major role in the system's behavior at finite temperatures.
Pu nuclear magnetic resonanceYasuoka, Hiroshi; Koutroulakis, G.*; Chudo, Hiroyuki; Richmond, S.*; Veirs, D. K.*; Smith, A. I.*; Bauer, E. D.*; Thompson, J. D.*; Jarvinen, G. D.*; Clark, D. L.*
Science, 336(6083), p.901 - 904, 2012/05
Times Cited Count：47 Percentile：85.78(Multidisciplinary Sciences)AlB; A Local-moment 4 magnet with a complex -
phase diagramRaumbach, R. E.*; Chudo, Hiroyuki; Yasuoka, Hiroshi; Ronning, F.*; Bauer, E. D.*; Thompson, J. D.*
Physical Review B, 85(9), p.094422_1 - 094422_7, 2012/03
Times Cited Count：31 Percentile：74.69(Materials Science, Multidisciplinary)
Np nuclear relaxation rate in heavy fermion superconductor NpPd AlChudo, Hiroyuki; Tokunaga, Yo; Kambe, Shinsaku; Sakai, Hironori; Haga, Yoshinori; Matsuda, Tatsuma; Onuki, Yoshichika; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; et al.
Physical Review B, 84(9), p.094402_1 - 094402_5, 2011/09
Times Cited Count：6 Percentile：29.25(Materials Science, Multidisciplinary)MnSiChudo, Hiroyuki; Ando, Kazuya*; Saito, Kesami*; Okayasu, Satoru; Haruki, Rie; Sakuraba, Yuya*; Yasuoka, Hiroshi; Takanashi, Koki; Saito, Eiji
Journal of Applied Physics, 109(7), p.073915_1 - 073915_4, 2011/04
Times Cited Count：19 Percentile：61.3(Physics, Applied)We present spin pumping using a Heusler alloy CoMnSi/Pt bilayer film. A spin current is produced by a ferromagnetic resonance (FMR) technique. The pure spin current injected into the Pt layer from the CoMnSi layer is detected by the inverse spin-Hall effect (ISHE), which converts the spin current into an electric current. We estimated a damping constant of the CoMnSi/Pt bilayer film from an angular dependence of FMR spectra. Using the damping constant efficiency of spin pumping from the CoMnSi layer is evaluated. We found that a mixing conductance at the CoMnSi/Pt interface is comparable to that at a permalloy/Pt interface.
Pr nuclear spin dynamics in PrPb; 
La NMR study in Pr
La
PbTokunaga, Yo; Sakai, Hironori; Chudo, Hiroyuki; Kambe, Shinsaku; Yasuoka, Hiroshi; Suzuki, Hiroyuki*; Walstedt, R. E.*; Homma, Yoshiya*; Aoki, Dai*; Shiokawa, Yoshinobu*
Physical Review B, 82(10), p.104401_1 - 104401_6, 2010/09
Times Cited Count：5 Percentile：26.3(Materials Science, Multidisciplinary)La NMR studies have been performed on PrPb substituted with 3% La. The temperature dependence of the local magnetic susceptibility around La ions has been extracted from the La Knight shift. These data show that the non-magnetic 
crystalline-electric-field (CEF) ground state (GS) is preserved even at the nearest neighboring Pr ions, although their CEF level scheme is slightly modified due to the La substitution. On the other hand, the temperature dependence of the nuclear spin-lattice relaxation rate is found to be well reproduced by assuming the same CEF level scheme over a wide temperature range. However, shows a strong upturn below 10 K, which is not expected from the non-magnetic CEF GS. We show that the low temperature anomaly can be quantitatively understood in terms of a cross-relaxation process between Pr and La nuclear spins.
AlChudo, Hiroyuki; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Aoki, Dai*; Homma, Yoshiya*; Haga, Yoshinori; Matsuda, Tatsuma; Onuki, Yoshichika; Yasuoka, Hiroshi
Journal of the Physical Society of Japan, 79(5), p.053704_1 - 053704_4, 2010/05
Times Cited Count：12 Percentile：59.61(Physics, Multidisciplinary)We present 
Al NMR measurements of the Knight shift and nuclear spin-lattice relaxation rate 1/
in the normal state for a single crystal of the heavy-fermion superconductor NpPd Al (
= 4.9 K). We report here that 1/ shows a large anisotropy with a different temperature dependence for 
and 
1/ for 
shows a power-law temperature dependence 
, while 1/ for shows a -linear dependence at low temperatures in fields well above 
. From the analysis of 1/, 
-type anisotropy of AFM spin fluctuations is found to become prominent below 20 K.
Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Matsuda, Tatsuma; Haga, Yoshinori; Yasuoka, Hiroshi; Chudo, Hiroyuki; Walstedt, R. E.*
Journal of Physics; Conference Series, 200, p.012076_1 - 012076_4, 2010/02
Times Cited Count：1 Percentile：46.67(Materials Science, Multidisciplinary)In order to clarify quantum criticality in heavy fermion systems, we propose to use the Gaussian spin-echo decay rate 
of the NMR spin-spin relaxation. In contrast to the spin-lattice relaxation rate , which is connected with the dynamical susceptibility Im
, is driven by the static susceptibility Re
at finite 
for an antiferromagnet. The combined quantity 
is found to provide key information in determining the nature of quantum criticality. The -dependence of for the Sn site in the heavy fermion compound USn is presented as an example.
Pd NQR study on NpPdAl and CePdAlChudo, Hiroyuki; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Aoki, Dai*; Haga, Yoshinori; Matsuda, Tatsuma; Homma, Yoshiya*; Nakano, Yasunori*; Honda, Fuminori*; et al.
Journal of Physics; Conference Series, 200, p.012020_1 - 012020_4, 2010/02
Times Cited Count：3 Percentile：74.25(Materials Science, Multidisciplinary)We report the results of Pd NQR experiments on NpPdAl and CePdAl. In the normal state at 6 K, the Pd NQR spectrum consists of four lines in both systems. These lines can be assigned to two sets of 
and 
NQR transitions arising from two crystallographically in equivalent Pd sites. From the analysis of the Pd NQR spectrum the nuclear quadrupole frequency , asymmetry parameter and electric field gradient 
have been deduced.
Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Chudo, Hiroyuki; Yasuoka, Hiroshi; Matsuda, Tatsuma; Haga, Yoshinori; Ikeda, Shugo; Nakamura, Akio; Yamamoto, Etsuji; et al.
Journal of Nuclear Materials, 385(1), p.1 - 3, 2009/03
Times Cited Count：1 Percentile：10.22(Materials Science, Multidisciplinary)In 5f-electron systems, exotic magnetism and unconventional superconductivity appear at low temperatures owing to strong electron correlations and orbital degeneracy. For example, we have investigated the unconventional superconducting states of recently synthesized NpPdAl (=5K) and PuRhGa (=9K) in terms of both macroscopic (staticsusceptibility, specific heat, resistivity) and microscopic (NMR) probes. The relation between magnetic fluctuations and unconventional superconductivity in f-electron systems is also discussed. Another exciting topic concerns the series AnO (An; U, Np, Pu, Am). Besides the importance of AnO as a nuclear fuel, the magnetic properties of these compounds at low temperatures are particularly interesting. On the basis of 
O-NMR studies, multipolar ordered states have been identified in UO (dipolar + quadrupolar ordering) and NpO (quadrupolar + octupolar ordering), in contrast with the non-magnetic ground state of PuO.
antiferromagnetism in cubic UIn; In-NMR/NQR studySakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Chudo, Hiroyuki; Tokiwa, Yoshifumi*; Aoki, Dai*; Haga, Yoshinori; Onuki, Yoshichika; Yasuoka, Hiroshi
Physical Review B, 79(10), p.104426_1 - 104426_7, 2009/03
Times Cited Count：6 Percentile：29.51(Materials Science, Multidisciplinary)In nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements have been performed on an antiferromagnet UIn with the cubic AuCu-type structure. Under zero field, the observation of the NQR spectrum has led to an estimated of 11.8 MHz at 90 K. The temperature variation of the NQR relaxation rates () far above the N
el temperature =88 K approaches a constant value, which indicates a localized nature for the 
-electrons in this system. On the other hand, in the antiferromagnetically ordered state, we propose that the most plausible direction of antiferromagnetic U moments may be 
among the possible orientations of 
, , or 
.
P-NMR study of hyperfine interactions and magnetic fluctuations in the neptunium-based filled skutterudite NpFe
P
Tokunaga, Yo; Kambe, Shinsaku; Sakai, Hironori; Chudo, Hiroyuki; Matsuda, Tatsuma; Haga, Yoshinori; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Shiokawa, Yoshinobu*; et al.
Physical Review B, 79(5), p.054420_1 - 054420_7, 2009/02
Times Cited Count：5 Percentile：25.59(Materials Science, Multidisciplinary)P-NMR measurements have been performed on a single crystal of the neptunium-based filled skutterudite NpFeP. We have observed transferred hyperfine interactions at the P sites, which lead to an estimate of the local spin density in the P 3
orbitals. It is shown that a fraction of the Np 5 spin moments is transferred mostly into the P 3 orbitals extending toward the inside of a P-cage. The weak hybridization between Np 5 and P 3 orbitals suggests a localized character for Np 5 electrons. We have also measured the field and temperature dependences of the nuclear spin-lattice relaxation rate (). The data reveal that the low-energy spin fluctuations of Np 5 spin moments are strongly suppressed by applied fields over a relatively wide temperature range. The present NMR results demonstrate that the negative magnetoresistance comes from a reduction of the magnetic scattering from Np 5 spin moments by an applied field.
