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Journal Articles

Magnetic, thermal, and neutron diffraction studies of a coordination polymer; bis(glycolato)cobalt(II)

Nakane, Tomohiro*; Yoneyama, Shota*; Kodama, Takeshi*; Kikuchi, Koichi*; Nakao, Akiko*; Ohara, Takashi; Higashinaka, Ryuji*; Matsuda, Tatsuma*; Aoki, Yuji*; Fujita, Wataru*

Dalton Transactions (Internet), 48(1), p.333 - 338, 2019/01

 Times Cited Count:1 Percentile:69.74(Chemistry, Inorganic & Nuclear)

Journal Articles

Phenomenological approach to study the degree of the itinerancy of the 5$$f$$ electrons in actinide ferromagnets with spin fluctuation theory

Tateiwa, Naoyuki; Posp$'i$$v{s}$il, J.*; Haga, Yoshinori; Sakai, Hironori; Matsuda, Tatsuma*; Yamamoto, Etsuji

Progress in Nuclear Science and Technology (Internet), 5, p.104 - 107, 2018/11

Uranium ferromagnetic superconductors UGe$$_2$$, URhGe and UCoGe have attracted much attention from both theoretical and experimental sides since the same 5$$f$$ electrons underlie carry both the ferromagnetism and superconductivity. Recently, we have analysed 69 uranium, 7 neptunium, and 4 plutonium ferromagnets with spin fluctuation theory originally developed for researches on itinerant ferromagnets in the 3$$d$$ transition metals and their intermetallics. The applicability of the spin fluctuation theory to the actinide 5$$f$$ system has been confirmed and the itinerant character of the 5f electrons is suggested in the actinide ferromagnets. In this conference, two results will be shown. One is the results of the analyses on 80 actinide ferromagnets and the other is the pressure dependence of the spin fluctuation parameters in UGe$$_2$$.

Journal Articles

Odd-parity electronic multipolar ordering in URu$$_2$$Si$$_2$$; Conclusions from Si and Ru NMR measurements

Kambe, Shinsaku; Tokunaga, Yo; Sakai, Hironori; Hattori, Taisuke; Higa, Nonoka; Matsuda, Tatsuma*; Haga, Yoshinori; Walstedt, R. E.*; Harima, Hisatomo*

Physical Review B, 97(23), p.235142_1 - 235142_10, 2018/06

AA2018-0180.pdf:1.09MB

 Times Cited Count:12 Percentile:20.55(Materials Science, Multidisciplinary)

Journal Articles

Element-specific observation of the ferromagnetic ordering process in UCoAl via soft X-ray magnetic circular dichroism

Takeda, Yukiharu; Saito, Yuji; Okane, Tetsuo; Yamagami, Hiroshi; Matsuda, Tatsuma*; Yamamoto, Etsuji; Haga, Yoshinori; Onuki, Yoshichika*

Physical Review B, 97(18), p.184414_1 - 184414_7, 2018/05

AA2018-0316.pdf:0.62MB

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

Journal Articles

Ruderman-Kittel interaction between Si in URu$$_{2}$$Si$$_{2}$$

Kambe, Shinsaku; Hattori, Taisuke; Tokunaga, Yo; Sakai, Hironori; Matsuda, Tatsuma*; Haga, Yoshinori; Walstedt, R. E.*

Journal of Physics; Conference Series, 969(1), p.012033_1 - 012033_6, 2018/03

 Times Cited Count:1 Percentile:23.99

High quality URu$$_{2}$$Si$$_{2}$$ enriched in $$^{29}$$Si isotope, which is an NMR nucleus, by 52% was prepared. Since the natural abundance ratio of $$^{29}$$Si isotope is about 4%, the accumulated measurement time can be shortened to about one hundredth by this concentration. Results of the Si-NMR linewidth of hidden ordered phase using this single crystal sample have already been reported. In this report, we will report more detailed analysis on the magnetic field, temperature and angle of this line width We also discuss the possibility of distribution of magnetic susceptibility in two-fold symmetry by RKKY model.

Journal Articles

Evidence for spin singlet pairing with strong uniaxial anisotropy in URu$$_2$$Si$$_2$$ using nuclear magnetic resonance

Hattori, Taisuke; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Matsuda, Tatsuma*; Haga, Yoshinori

Physical Review Letters, 120(2), p.027001_1 - 027001_5, 2018/01

 Times Cited Count:6 Percentile:28.4(Physics, Multidisciplinary)

Journal Articles

Itinerant ferromagnetism in actinide $$5f$$-electron systems; Phenomenological analysis with spin fluctuation theory

Tateiwa, Naoyuki; Posp$'i$$v{s}$il, J.*; Haga, Yoshinori; Sakai, Hironori; Matsuda, Tatsuma*; Yamamoto, Etsuji

Physical Review B, 96(3), p.035125_1 - 035125_15, 2017/07

 Times Cited Count:12 Percentile:29.06(Materials Science, Multidisciplinary)

We have carried out an analysis of magnetic data in 69 uranium, 7 neptunium and 4 plutonium ferromagnets with the spin fluctuation theory developed by Takahashi (Y. Takahashi, J. Phys. Soc. Jpn. ${bf 55}$, 3553 (1986)). The basic and spin fluctuation parameters of the actinide ferromagnets are determined and the applicability of the spin fluctuation theory to actinide $$5f$$ system has been discussed. Itinerant ferromagnets of the $$3d$$ transition metals and their intermetallics follow a generalized Rhodes-Wohlfarth relation $${p_{rm eff}}/{p_{rm s}}{,}{propto}{,}({T_{rm C}}/{T_0})^{-3/2}$$. Here, $$p_{rm s}$$, $$p_{rm eff}$$, $$T_{rm C}$$, and $$T_0$$ are the spontaneous and effective magnetic moments, the Curie temperature and the width of spin fluctuation spectrum in energy space, respectively. The same relation is satisfied for $${T_{rm C}}/{T_0}< 1.0$$ in the most of the actinide ferromagnets.

Journal Articles

$$T$$ dependence of nuclear spin-echo decay at low temperatures in YbRh$$_2$$Si$$_2$$

Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Hattori, Taisuke; Lapertot, G.*; Matsuda, Tatsuma*; Knebel, G.*; Flouquet, J.*; Walstedt, R. E.*

Physical Review B, 95(19), p.195121_1 - 195121_8, 2017/05

AA2017-0083.pdf:0.74MB

 Times Cited Count:3 Percentile:69.64(Materials Science, Multidisciplinary)

The authors report $$^{29}$$Si nuclear spin-echo oscillations and decay measurements on a single crystal of YbRh$$_2$$Si$$_2$$. These quantities are found to be $$T$$ independent from 300 K down to $$sim$$20 K, showing, however, a strong $$T$$ dependence below 20 K. These results indicate that electronic states near the Fermi level are modified at low temperatures. The observed spin-echo oscillations can be interpreted with the Ruderman-Kittel and pseudo-dipolar interactions between nearest-neighbor Si nuclei driven by conduction electron scattering at the Fermi surface. Possible modifications to the Fermi surface at low temperatures are discussed.

Journal Articles

Fermi surface of ThRu$$_{2}$$Si$$_{2}$$ as a reference to the strongly correlated isostructural metals investigated by quantum oscillations

Matsumoto, Yuji*; Haga, Yoshinori; Tateiwa, Naoyuki; Aoki, Haruyoshi*; Kimura, Noriaki*; Yamamura, Tomoo*; Yamamoto, Etsuji; Matsuda, Tatsuma*; Fisk, Z.*; Yamagami, Hiroshi*

Journal of the Physical Society of Japan, 85(10), p.104709_1 - 104709_7, 2016/10

 Times Cited Count:2 Percentile:71.04(Physics, Multidisciplinary)

Journal Articles

No detectable change in in-plane $$^{29}$$Si knight shift in the superconducting state of URu$$_2$$Si$$_2$$

Hattori, Taisuke; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Matsuda, Tatsuma*; Haga, Yoshinori

Journal of the Physical Society of Japan, 85(7), p.073711_1 - 073711_4, 2016/07

 Times Cited Count:7 Percentile:38.35(Physics, Multidisciplinary)

Using a high-quality single crystal of URu$$_2$$Si$$_2$$, we performed $$^{29}$$Si Knight shift measurements with an applied magnetic field $$H^a$$ along the crystalline $$a$$ axis, i.e., along the magnetic hard axis, for temperatures down to 50 mK. The narrow, single-peak $$^{29}$$Si NMR spectrum obtained from this crystal allowed us to examine the temperature variation of the Knight shift $$K(T)$$, and hence, that of the variation of the spin susceptibility with sensitivity on the order of 0.001%. At this precision, no observable change in $$K(T)$$ was detected from 50 mK up to the superconducting transition at $$T_{rm SC}(H^a)sim$$ 1 K. Our results correspond to either an extremely small spin susceptibility in the hidden-order state along the magnetic hard axis or to possible spin-triplet superconductivity in this system.

Journal Articles

$$^{29}$$Si NMR spin-echo decay in YbRh$$_2$$Si$$_2$$

Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Hattori, Taisuke; Lapertot, G.*; Matsuda, Tatsuma*; Knebel, G.*; Flouquet, J.*; Walstedt, R. E.*

Journal of Physics; Conference Series, 683(1), p.012006_1 - 012006_7, 2016/02

 Times Cited Count:1 Percentile:32.49

By means of nuclear magnetic resonance (NMR) spin-lattice relaxation time ($$T_1$$) measurements on a single crystal sample YbRh$$_2$$Si$$_2$$, the magnetic excitations around quantum critical phase transition is investigated. It is revealed that the coexisting Fermi and non-Fermi states appears near the quantum critical phase transition. Such a mottled state is considered to have remained hidden in Ce and U heavy fermion compounds, owing presumably to short lifetimes for the two states. The mottled state is highly anisotropic to applied magnetic field, which is consistent with previous studies. The origin of mottled state will be discussed.

Journal Articles

Anisotropic magnetic fluctuations in YbRh$$_2$$Si$$_2$$

Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Lapertot, G.*; Matsuda, Tatsuma*; Knebel, G.*; Flouquet, J.*; Walstedt, R. E.*

Journal of Physics; Conference Series, 592(1), p.012085_1 - 012085_5, 2015/03

 Times Cited Count:2 Percentile:30.21

Recently there is renewed interest in quantum critical phase transitions (QCPT) at $$T=0$$ K in metallic strongly-correlated electron systems. From early experimental results, the QCPT in the Kondo-lattice compound YbRh$$_2$$Si$$_2$$ is not a case of the ordinary spin density wave (SDW) instability observed in Ce-based Kondo-lattices, but a candidate for a novel locally critical case In new observations reported here, we find that coexisting, static Fermi liquid (FL) and non-Fermi liquid (NFL) states are a key feature of the QCPT in YbRh$$_2$$Si$$_2$$. Such a pair of states has remained hidden in Ce compounds, owing presumably to short lifetimes for the two states. A new scaling law for the occupation ratio of the two states is derived, and could be widely applicable to Kondo-lattice systems.

Journal Articles

Colossal thermomagnetic response in the exotic superconductor URu$$_2$$Si$$_2$$

Yamashita, Takuya*; Shimoyama, Yusuke*; Haga, Yoshinori; Matsuda, Tatsuma*; Yamamoto, Etsuji; Onuki, Yoshichika; Sumiyoshi, Hiroaki*; Fujimoto, Satoshi*; Levchenko, A.*; Shibauchi, Takasada*; et al.

Nature Physics, 11(1), p.17 - 20, 2015/01

 Times Cited Count:31 Percentile:10.71(Physics, Multidisciplinary)

Journal Articles

Degenerate Fermi and non-Fermi liquids near a quantum critical phase transition

Kambe, Shinsaku; Sakai, Hironori; Tokunaga, Yo; Lapertot, G.*; Matsuda, Tatsuma*; Knebel, G.*; Flouquet, J.*; Walstedt, R. E.*

Nature Physics, 10(11), p.840 - 844, 2014/11

 Times Cited Count:17 Percentile:22.97(Physics, Multidisciplinary)

In new observations reported here, we find that coexisting, static Fermi liquid and non-Fermi liquid states are a key feature of the QCPT in YbRh$$_{2}$$Si$$_{2}$$. By means of nuclear magnetic resonance (NMR) spin-lattice relaxation time measurements on a single crystal sample, it is revealed that the FL and NFL states are invariant,while their relative proportion in a crossover is field dependent near the QCPT. Such a pair of states has remained hidden in Ce compounds, owing presumably to short lifetimes for the two states. A new scaling law for the occupation ratio of the two states is derived, and could be widely applicable to Kondo-lattice systems

Journal Articles

Single crystal growth and characterization of URu$$_2$$Si$$_2$$

Haga, Yoshinori; Matsuda, Tatsuma*; Tateiwa, Naoyuki; Yamamoto, Etsuji; Onuki, Yoshichika; Fisk, Z.

Philosophical Magazine, 94(32-33), p.3672 - 3680, 2014/11

 Times Cited Count:5 Percentile:62.32(Materials Science, Multidisciplinary)

Journal Articles

Influence of electron doping on magnetic order in CeRu$$_2$$Al$$_{10}$$

Kobayashi, Riki*; Kaneko, Koji; Saito, Kotaro*; Mignot, J.-M.*; Andr$'e$, G.*; Robert, J.*; Wakimoto, Shuichi; Matsuda, Masaaki*; Chi, S.*; Haga, Yoshinori; et al.

Journal of the Physical Society of Japan, 83(10), p.104707_1 - 104707_5, 2014/10

 Times Cited Count:13 Percentile:28.67(Physics, Multidisciplinary)

Journal Articles

Spin polarized neutron scattering study on metal-insulator crossover in uranium dichalcogenide $$beta$$-US$$_{2}$$

Metoki, Naoto; Sakai, Hironori; Suzuki, Michito; Yamamoto, Etsuji; Haga, Yoshinori; Matsuda, Tatsuma; Ikeda, Shugo*

JPS Conference Proceedings (Internet), 3, p.013011_1 - 013011_6, 2014/06

Uranium chalcogenides are highly interesting because of the variety of the physical properties from 5$$f$$-based metal and Mott-Hibbard insulator. Especially dichalcogenide family exhibits a metal-insulator crossover depending on the chalcogenide elements, or under magnetic field and pressure. In this talk we present a recent result of our neutron scattering study on uranium dichalcogenide, which demonstrates that the metal-insulator crossover is related to the change of 5$$f$$ character from localized to itinerant. The electronic structure related to this phenomenon is discussed based on the band calculation.

Journal Articles

Single-crystal growth and de Haas-van Alphen effect study of ThRu$$_2$$Si$$_2$$

Matsumoto, Yuji*; Haga, Yoshinori; Tateiwa, Naoyuki; Aoki, Haruyoshi*; Kimura, Noriaki*; Matsuda, Tatsuma*; Yamamoto, Etsuji; Fisk, Z.; Yamagami, Hiroshi*

JPS Conference Proceedings (Internet), 3, p.011096_1 - 011096_5, 2014/06

Journal Articles

Unique Fermi surface and emergence of charge density wave in EuGa$$_4$$ and EuAl$$_4$$

Nakamura, Ai*; Hiranaka, Yuichi*; Hedo, Masato*; Nakama, Takao*; Miura, Yasunao*; Tsutsumi, Hiroki*; Mori, Akinobu*; Ishida, Kazuhiro*; Mitamura, Katsuya*; Hirose, Yusuke*; et al.

JPS Conference Proceedings (Internet), 3, p.011012_1 - 011012_6, 2014/06

Journal Articles

Direct observation of lattice symmetry breaking at the hidden-order transition in URu$$_2$$Si$$_2$$

Tonegawa, Sho*; Kasahara, Shigeru*; Fukuda, Tatsuo; Sugimoto, Kunihisa*; Yasuda, Nobuhiro*; Tsuruhara, Yugo*; Watanabe, Daiki*; Mizukami, Yuta*; Haga, Yoshinori; Matsuda, Tatsuma*; et al.

Nature Communications (Internet), 5, p.4188_1 - 4188_7, 2014/06

 Times Cited Count:45 Percentile:8.09(Multidisciplinary Sciences)

428 (Records 1-20 displayed on this page)