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Mizuta, Yoshio*; Hosokai, Tomonao*; Masuda, Shinichi*; Zhidkov, A.*; Makito, Keigo*; Nakanii, Nobuhiko*; Kajino, Shohei*; Nishida, Akinori*; Kando, Masaki; Mori, Michiaki; et al.
Physical Review Special Topics; Accelerators and Beams, 15(12), p.121301_1 - 121301_10, 2012/12
Times Cited Count：21 Percentile：69.86(Physics, Nuclear)
diffusion in cubic 
-electron compounds observed by high transverse field SRIto, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Nishida, Nobuhiko*; Heffner, R. H.; Aoki, Yuji*; Suzuki, Hiroyuki*; Onimaru, Takahiro*; Tanida, Hiroshi*; Takagi, Shigeru*
Journal of Physics; Conference Series, 225, p.012021_1 - 012021_6, 2010/06
Times Cited Count：2 Percentile：65.13(Physics, Applied)The diffusion of positive muon in condensed matter has been investigated for many years by using spin rotation/relaxation (SR) technique. The SR studies have provided deep insight into quantum diffusion at low temperatures as well as hopping process at high temperatures, which are closely related to hydrogen dynamics in the dilute limit. We here report transverse field (TF) SR studies of the diffusion in cubic -electron compounds PrPb
and SmAg
In. The site splits into two magnetically labeled sites when high TF is applied to single-crystalline specimens along the [001] direction. The SR lines show drastic variation according to the motion between the magnetically labeled sites. From detailed analysis of the SR lines, we deduced hopping parameters for both compounds.
Sato, Hideyuki*; Aoki, Yuji*; Kikuchi, Daisuke*; Sugawara, Hitoshi*; Higemoto, Wataru; Oishi, Kazuki; Ito, Takashi; Heffner, R. H.; Saha, S. R.*; Koda, Akihiro*; et al.
Physica B; Condensed Matter, 404(5-7), p.749 - 753, 2009/04
Times Cited Count：5 Percentile：24.22(Physics, Condensed Matter)Wide varieties of strongly correlated electron phenomena are performed on the stage of a filled skutterudite structure. Especially when one of the players contains a plural number of 4f electrons, the orbital degrees of freedom play a major role as a new type of nonmagnetic and/or weak-magnetic phenomena. Several examples found in Pr- and Sm-based filled skutterudites are introduced in relation to muon spin relaxation experiments.
P
probed by muon spin relaxationIto, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; Sato, Hideyuki*
Physica B; Condensed Matter, 404(5-7), p.761 - 764, 2009/04
Times Cited Count：1 Percentile：5.48(Physics, Condensed Matter)We report on detailed longitudinal field (LF) 
SR studies in SmRuP in order to characterize magnetic fluctuations in a magnetically ordered state below 
K. A magnitude and fluctuation rate of the fluctuating field are derived as functions of temperature from LF dependence of the longitudinal relaxation rate. Possible low-energy excitations of magnetic multipoles are discussed.
site in PrPb; Interplay between localized electrons and an interstitial charged particleIto, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Nishida, Nobuhiko*; Heffner, R. H.; Aoki, Yuji*; Amato, A.*; Onimaru, Takahiro*; Suzuki, Hiroyuki*
Physical Review Letters, 102(9), p.096403_1 - 096403_4, 2009/03
Times Cited Count：14 Percentile：61.24(Physics, Multidisciplinary)
P probed by SRIto, Takashi; Higemoto, Wataru; Oishi, Kazuki; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; Sato, Hideyuki*
Journal of Physics and Chemistry of Solids, 68(11), p.2072 - 2075, 2007/11
Times Cited Count：1 Percentile：7.18(Chemistry, Multidisciplinary)no abstracts in English
P probed by muon spin relaxationIto, Takashi; Higemoto, Wataru; Oishi, Kazuki; Fujimoto, Tatsuya*; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; et al.
Journal of the Physical Society of Japan, 76(5), p.053707_1 - 053707_4, 2007/05
Times Cited Count：27 Percentile：73.76(Physics, Multidisciplinary)A filled skutterudite compound SmRuP shows metal-insulatortransition at 
=16.5K with magnetic anomaly. A possibility of magnetic octupole ordering has been discussed on the basis of multipole degrees of freedom belonging to thecrystalline-electric-field ground state. We investigated local magnetic states in the ordered state by using the muon spin relaxation method. An increase of muon spin relaxation rate was detected in zeroapplied field just below , indicating time-reversal-symmetry breaking in the ordered state. This result suggests that the order parameter includes magnetic octupole and/ordipole. Magnitude of the internal field at the muon site monotonically increases with decreasing temperature, growing steeply below 
=3K. The longitudinal relaxation rate has a maximum at around , suggesting suppression of magnetic fluctuations. We discussed these experimental facts on the basis of the multipoledegrees of freedom.
in paraquadrupolar stateIto, Takashi; Higemoto, Wataru; Oishi, Kazuki; Heffner, R. H.; Nishida, Nobuhiko*; Aoki, Yuji*; Onimaru, Takahiro*; Suzuki, Hiroyuki*
Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.743 - 745, 2007/00
Times Cited Count：4 Percentile：21.53(Materials Science, Multidisciplinary)PrPb exhibits antiferroquadrupole ordering at T
= 0.4 K. In the ordering phase, incommensurate structure of quadruple was found from recent experimental study and much attention is paid to this compound. We performed muon spin rotation and relaxation measurements on a single crystalline sample of PrPb. A quite anisotropic contact-coupling constant was extracted from the muon Knight shift, possibly concerned with nonspherical distribution of 4-electron at low temperature. The contact and dipole coupling constants are of comparable magnitudes, suggesting significance of strong hybridization between the 
electrons of Pr and the conduction electrons for incommensurate structure.
Ito, Takashi; Nishida, Nobuhiko*; Oishi, Kazuki; Higemoto, Wataru; Karaki, Yoshitomo*; Ishimoto, Hidehiko*
Journal of the Physical Society of Japan, 75(Suppl.), p.189 - 191, 2006/08
no abstracts in English
at very low temperatureHigemoto, Wataru; Sato, Kazuhiko*; Ito, Takashi; Nishida, Nobuhiko*; Oishi, Kazuki*; Heffner, R. H.; Haga, Yoshinori; Yamamoto, Etsuji; Kimura, Noriaki*; Onuki, Yoshichika; et al.
no journal, ,
The unconventional superconductivity in heavy fermion UPt attracted much interest. In recent neutron experiment, the narrowing of the AF Bragg peak at low temperature was observed, from which they suggest that a quasistatic AF long range order is realized below 20 mK. We have extended ZF-SR measurement down to 8 mK to investigate the anomalous magnetic state over the very low temperature region. In our ZF-SR, there is no significant change in the muon spinrelaxation rate down to 8 mK. The result suggests the absence of static or quasistaticmagnetic order over the relevant temperature range.
electron systemsIto, Takashi; Higemoto, Wataru; Oishi, Kazuki; Fujimoto, Tatsuya; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; et al.
no journal, ,
no abstracts in English
diffusion and trapping in dilute Fe alloys by longitudinal spin relaxation techniqueNishida, Nobuhiko*; Higemoto, Wataru; Ito, Takashi
no journal, ,
In the late 1970s and 1980s muon spin rotation experiments were performed elaborately to study muon diffusion and trapping in Fe and Fe alloys. Recently, we have found that the measurement of the longitudinal muon spin relaxation time in ferromagnetic Fe alloys is the effective technique to study the muon diffusion and trapping in Fe dilute alloys and to investigate how the hydrogen interacts with the principal alloying elements We revisit the SR studies of diffusion and trapping in Fe alloys. In some alloys, we found the temperature dependence of muon spin relaxation time exhibits the peaks and in some other alloys a hump in a broad temperature region.
P at low temperature and low field probed by SRIto, Takashi; Higemoto, Wataru; Oishi, Kazuki; Fujimoto, Tatsuya; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; et al.
no journal, ,
no abstracts in English
Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Nishida, Nobuhiko*; Aoki, Yuji*; Onimaru, Takahiro*; Suzuki, Hiroyuki*
no journal, ,
no abstracts in English
-Pr in PrPbIto, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Nishida, Nobuhiko*; Heffner, R. H.; Aoki, Yuji*; Amato, A.*; Onimaru, Takahiro*; Suzuki, Hiroyuki*
no journal, ,
An isolated few-spin system including a spin 
is usually unlikely to be realized in metal. Contrary to the expectation, we actually found an isolated three-spin system 
Pr--Pr in a rare-earth intermetallic compound PrPb. This system results in spin precession with six frequencies at regular intervals. Such harmonic frequencies cannot be obtained only from dipolar interactions between and bare Pr nuclear spins 
. Extremely anisotropic enhancement of the - coupling is required. This enhancement can be explained by mechanism of the Pr hyperfine-enhanced nuclear magnetism and -induced perturbation on 4f-electronic state of two Pr ions next to the .
P at low temperature and low field probed by SRIto, Takashi; Higemoto, Wataru; Oishi, Kazuki; Fujimoto, Tatsuya; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; et al.
no journal, ,
no abstracts in English
P detected by muon spin relaxationIto, Takashi; Higemoto, Wataru; Oishi, Kazuki; Fujimoto, Tatsuya; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; et al.
no journal, ,
no abstracts in English
SR study on multipolar ordering in PrPb, 2Ito, Takashi; Higemoto, Wataru; Oishi, Kazuki; Heffner, R. H.; Nishida, Nobuhiko*; Aoki, Yuji*; Onimaru, Takahiro*; Suzuki, Hiroyuki*
no journal, ,
no abstracts in English
Pr-based compounds observed by muon spin relaxationIto, Takashi; Higemoto, Wataru; Oishi, Kazuki; Nishida, Nobuhiko*; Karaki, Yoshitomo*; Ishimoto, Hidehiko*
no journal, ,
Several novel phenomena about higher order multipoles have recently been found in Pr-based compounds with a nonmagnetic crystalline-electric-field (CEF) ground state. Previous SR studies in such compounds reported an anomalous muon spin relaxation at low temperatures in spite of the CEF ground state with the nonmagnetic nature, and a hyperfine-enhanced nuclear magnetism was discussed as the origin. A Van-Vleck paramagnet PrPt is a typical system of the enhanced nuclear magnetism, which exhibits a ferromagnetic nuclear ordering at 
=1.7 mK. This compound has been well characterized and is an ideal system to clarify a relation between the enhanced nuclear magnetism and the anomalous muon spin relaxation in Pr-based compounds. We performed SR measurements down to 50 mK. An internal field observed at the muon site is much larger in magnitude than ones due to bare nuclear dipole moments, suggesting an induction of 4 magnetic moments. A fluctuation rate 
of the field was estimated in the order of a few MHz and the value for is consistent with one estimated from . Our observations demonstrate that the SR is an ideal tool to investigate the dynamics of the hyperfine-enhanced nuclear spins in electron systems.
P probed by SRIto, Takashi; Higemoto, Wataru; Oishi, Kazuki*; Heffner, R. H.; Nishida, Nobuhiko*; Sato, Kazuhiko*; Sugawara, Hitoshi*; Aoki, Yuji*; Kikuchi, Daisuke*; Sato, Hideyuki*
no journal, ,
The filled skutterudite compound SmRuP exhibits a metal-insulator (MI) transition at 
16.5 K. An entropy release 
below suggests that the crystalline-electric-field ground state is a 
quartet with various multipole degrees of freedom. A possibility of magnetic octupole ordering has been intensively discussed to explain the time-reversal-symmetry breaking, anomalous elastic properties, and a complex field-temperature phase diagram. We will report SR measurements on single crystalline samples of SmRuP to investigate the nature of the multipoles in the ordered state. A remarkable longitudinal relaxation was observed in the ordered state, the magnitude of which was reduced below 3 K. We will discuss possible low-energy excitations of magnetic multipoles in the ordered state and their influence on the local magnetic probe on the basis of symmetry of the multipoles.
