Precise magnetization measurements down to 500 mK using a miniature He cryostat and a closed-cycle He gas handling system installed in a SQUID magnetometer without continuous-cooling functionality

Shimamura, Kazutoshi*; Wajima, Hiroki*; Makino, Hayato*; Abe, Satoshi*; Haga, Yoshinori; Sato, Yoshiaki*; Kawae, Tatsuya*; Yoshida, Yasuo*

Japanese Journal of Applied Physics, 61(5), p.056502_1 - 056502_7, 2022/05

https://doi.org/10.35848/1347-4065/ac5bb0

DC magnetization study on heavy-electron superconductor UBe

Shimizu, Yusei*; Haga, Yoshinori; Yanagisawa, Tatsuya*; Amitsuka, Hiroshi*; Aoki, Dai*; Brison, J.-P.*; Braithwaite, D.*

JPS Conference Proceedings (Internet), 3, p.015009_1 - 015009_6, 2014/06

https://doi.org/10.7566/JPSCP.3.015009

Maki parameter and upper critical field of the heavy-fermion superconductor UBe

Shimizu, Yusei*; Ikeda, Yoichi*; Wakabayashi, Takumi*; Haga, Yoshinori; Tenya, Kenichi*; Hidaka, Hiroyuki*; Yanagisawa, Tatsuya*; Amitsuka, Hiroshi*

Journal of the Physical Society of Japan, 80(9), p.093701_1 - 093701_4, 2011/09

https://doi.org/10.1143/JPSJ.80.093701

Ultrasonic measurements on the cage-structured clathrate compound UPdSi

Yanagisawa, Tatsuya*; Tateiwa, Naoyuki; Mayama, Taichi*; Saito, Hitoshi*; Hidaka, Hiroyuki*; Amitsuka, Hiroshi*; Haga, Yoshinori; Nemoto, Yuichi*; Goto, Terutaka*

Journal of the Physical Society of Japan, 80(Suppl.A), p.SA105_1 - SA105_3, 2011/07

https://doi.org/10.1143/JPSJS.80SA.SA105

Ga NQR relaxation rates in superconductor PuRhGa

Sakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Fujimoto, Tatsuya; Walstedt, R. E.*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; et al.

Journal of Physics and Chemistry of Solids, 68(11), p.2103 - 2106, 2007/11

https://doi.org/10.1016/j.jpcs.2007.08.039

A lot of attention is currently focused on Pu-based superconductors. These systems have relatively high superconducting (SC) transition temperatures, 18 K for PuCoGa and 9 K for PuRhGa. Both compounds crystallize in the tetragonal HoCoGa (115) structure, which is well known for the heavy-fermion SC systems CeIn (=Co, Rh, Ir)with 2 K at most. Recently, NMR and NQR experiments have been reported for PuCoGa by Curro et al. and for PuRhGa by our group. In both cases, measurements of using NQR have revealed that the Pu115 superconductors show unconventional superconductivity with an anisotropic gap. Now we have measured the more detailed data of for NQR lines in PuRhGa, especially focusing on the low-lying magnetic excitation in the normal state. From the viewpoint of spin-fluctuations, we will discuss the difference between PuRhGa and PuCoGa and between superconducting Pu115 and non-superconducting An115 series.

NMR study of the semimetallic compound UCoGa

Kambe, Shinsaku; Sakai, Hironori; Kato, Harukazu*; Tokunaga, Yo; Fujimoto, Tatsuya*; Walstedt, R. E.*; Ikeda, Shugo; Maehira, Takahiro*; Haga, Yoshinori; Onuki, Yoshichika

Physical Review B, 76(2), p.024411_1 - 024411_6, 2007/07

https://doi.org/10.1103/PhysRevB.76.024411

We report NMR studies on a single crystal of UCoGa, which has the same tetragonal HoCoGa (115) structure as the-wave high- superconductor PuCoGa. The spin-lattice relaxation rate () in UCoGa issmall comparing with those of other actinide 115 compounds. This fact is consistent with a semi-metallic nature of UCoGa suggested by de Haas-van Alphen effect measurements and band calculations. From comparison of at crystallografically different Ga and Co sites and the static susceptibility, an existence of two bands with rather different characters is revealed.

NMR/NQR study of the quadrupole orders in binary uranium-palladium intermetallic compound

Fujimoto, Tatsuya; Haga, Yoshinori; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Onuki, Yoshichika*

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.746 - 747, 2007/03

UPd shows the successive quadrupole orders at K, K and K. The phase transition at comes from the (1/2,0,1/2)-type quadrupole orders on quasi-cubic uranium-sublattice. On the other hand, the quadrupole states below are still controversial; while the Polarized Neutron Diffraction suggested the triple- structure, the Resonant X-ray Scattering assumed the canted quadrupole order. In addition, below , an antiferromagnetic order has been suggested, but the magnetic structure and so on are not still identified. To investigate the local symmetry of the quadruple order in UPd, we tried the nuclear quadrupole resonance, and we succeeded to find the first spin-echo signals from the UPd probed by Pd nuclei. In this paper, we report the nuclear properties of Pd isotope and discuss the characteristics of the quadrupole orders emerging in each temperature phases.

Enhancement of relaxation rates in the normal state of superconductor PuRhGa:NQR relaxation study

Sakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Fujimoto, Tatsuya; Walstedt, R. E.*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; et al.

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.e118 - e119, 2007/03

The spin-lattice relaxation rates () have been measured under zero fieldusing nuclear quadrupole resonance (NQR) linesin superconductor PuRhGa and Pauli-paramagnet LuCoGa. In the reference LuCoGa with fully-occupied shell, the shows the constant behavior of (secK). On the other hand, in PuRhGa, is much larger than in LuCoGaand the behavior below 30 K is seen, where its value is 3.27 0.005 (secK). These results suggest a development of coherent Fermi liquid stateincorporated with electronsbelow 30 K in PuRhGa.

Observation of ferromagnetic and antiferromagnetic correlations in UIrB

Fujimoto, Tatsuya; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Walstedt, R. E.; Ikeda, Shugo; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika

Journal of the Physical Society of Japan, 75(Suppl.), p.113 - 115, 2006/08

The low-dimensional systems exhibit wide-variety of physical properties. In the antiferromagnetic triangular lattice, for instance, resonating valence bond state is expected, furthermore, in one-dimensional (1D) systems, metal-insulator transition (Peierls transition) occurs due to charge-lattice couplings. Up to now, the study of low-dimensional systems has been mostly performed in oxides and organic compounds, but it is rare in the rare-earth and actinide intermetallics. To looking for the novel low-dimensionality in -electron systems, we focused on the UIrB, and NMR measurement was carried out. From Knight shift and nuclear spin-lattice relaxation rates, ferromagnetic correlations develop above 50 K, but below 50 K, the emergence of antiferromagnetic correlations was clarified along with the saturation of ferromagnetic correlations. The possible model to explain the obtained result is nesting effect on the 1D Fermi surface, and it is expected that UIrB will be the typical compound to investigate the physical properties of 1D -electrons systems.

Anomalous magnetic correlations in heavy fermion Pauli paramagnet UIrB; B NMR study

Fujimoto, Tatsuya; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Walstedt, R. E.; Ikeda, Shugo; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika

Physica B; Condensed Matter, 378-380, p.997 - 998, 2006/05

https://doi.org/10.1016/j.physb.2006.01.382

We report B NMR results of a single crystal UIrB. The measurement was performed by Fast Fourier Transformation technique, because spectral line width is extremely narrow ( 10 kHz) and NMR occurs in quite limited r.f. band due to a good sample quality. From temperature variation of Knight shift and nuclear spin-lattice relaxation rate, the development of ferromagnetic correlations was clarified in the temperature range above K. On the other hand, the magnetic dynamics was changed into another novel state below ; ferromagnetic correlations are restrained, meanwhile antiferromagnetic correlations are newly emerged. To explain this characteristic ground state, the one-dimensional electrons state due to the unique structural lattice of UIrB was proposed.