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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)Kinjo, Katsuki*; Fujibayashi, Hiroki*; Matsumura, Hiroki*; Hori, Fumiya*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; et al.
Science Advances (Internet), 9(30), p.2736_1 - 2736_6, 2023/07
Times Cited Count：0 Percentile：0(Multidisciplinary Sciences)
-axis knight shift on UTe with 
= 2.1 KMatsumura, Hiroki*; Fujibayashi, Hiroki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; et al.
Journal of the Physical Society of Japan, 92(6), p.063701_1 - 063701_5, 2023/05
Times Cited Count：5 Percentile：92.42(Physics, Multidisciplinary) along hard magnetic axisSakai, Hironori; Tokiwa, Yoshifumi; Opletal, P.; Kimata, Motoi*; Awaji, Satoshi*; Sasaki, Takahiko*; Aoki, Dai*; Kambe, Shinsaku; Tokunaga, Yo; Haga, Yoshinori
Physical Review Letters, 130(19), p.196002_1 - 196002_6, 2023/05
Times Cited Count：5 Percentile：92.42(Physics, Multidisciplinary)The superconducting (SC) phase diagram in uranium ditelluride is explored under magnetic fields (
) along the hard magnetic 
-axis using a high-quality single crystal with 
= 2.1 K. Simultaneous electrical resistivity and AC magnetic susceptibility measurements discern low- and high-field SC (LFSC and HFSC, respectively) phases with contrasting field-angular dependence. Crystal quality increases the upper critical field of the LFSC phase, but the 
of 
T, at which the HFSC phase appears, is always the same through the various crystals. A phase boundary signature is also observed inside the LFSC phase near , indicating an intermediate SC phase characterized by small flux pinning forces.
Tokunaga, Yo; Sakai, Hironori; Kitagawa, Shunsaku*; Ishida, Kenji*
Nihon Butsuri Gakkai-Shi, 78(5), p.267 - 272, 2023/04
no abstracts in English
induced by magnetic fieldKinjo, Katsuki*; Fujibayashi, Hiroki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; Homma, Yoshiya*; et al.
Physical Review B, 107(6), p.L060502_1 - L060502_5, 2023/02
Times Cited Count：7 Percentile：93.16(Materials Science, Multidisciplinary)Aoki, Dai*; Brison, J.-P.*; Flouquet, J.*; Ishida, Kenji*; Knebel, G.*; Tokunaga, Yo; Yanase, Yoichi*
Journal of Physics; Condensed Matter, 34(24), p.243002_1 - 243002_41, 2022/06
Times Cited Count：54 Percentile：87.73(Physics, Condensed Matter) under pressure revealed by 
Te-NMRKinjo, Katsuki*; Fujibayashi, Hiroki*; Nakamine, Genki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; et al.
Physical Review B, 105(14), p.L140502_1 - L140502_5, 2022/04
Times Cited Count：5 Percentile：67.2(Materials Science, Multidisciplinary)Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Haga, Yoshinori; Tokiwa, Yoshifumi; Opletal, P.; Fujibayashi, Hiroki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; et al.
Journal of the Physical Society of Japan, 91(2), p.023707_1 - 023707_5, 2022/02
Times Cited Count：14 Percentile：93.17(Physics, Multidisciplinary)Te NMR experiments in field () applied along the easy magnetization axis (the -axis) revealed slow electronic dynamics developing in the paramagnetic state of UTe. The observed slow fluctuations are concerned with a successive growth of long-range electronic correlations below 30
40 K, where the spin susceptibility along the hard magnetization axis (the -axis) shows a broad maximum. The experiments also imply that tiny amounts of disorder or defects locally disturb the long-range electronic correlations and develop an inhomogeneous electronic state at low temperatures, leading to a low temperature upturn observed in the bulk-susceptibility in 
. We suggest that UTe would be located on the paramagnetic side near an electronic phase boundary, where either the magnetic or Fermi-surface instability would be the origin of the characteristic fluctuations.
Te NMR on UTeNakamine, Genki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; Homma, Yoshiya*; et al.
Journal of the Physical Society of Japan, 90(6), p.064709_1 - 064709_7, 2021/06
Times Cited Count：17 Percentile：85.26(Physics, Multidisciplinary) probed with Te-NMR measurementNakamine, Genki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; Homma, Yoshiya*; et al.
Physical Review B, 103(10), p.L100503_1 - L100503_5, 2021/03
Times Cited Count：32 Percentile：93.31(Materials Science, Multidisciplinary) revealed by Te-nuclear magnetic resonanceNakamine, Genki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; Homma, Yoshiya*; Li, D.*; et al.
Journal of the Physical Society of Japan, 88(11), p.113703_1 - 113703_4, 2019/11
Times Cited Count：68 Percentile：95.42(Physics, Multidisciplinary)Tokunaga, Yo
no journal, ,
We report our recent NMR studies on the novel spin-triplet superconductor UTe, which is at the verge of the ferromagnetic order. The upper critical field H
exceeding the Pauli limit indicates the spin-triplet state. For the field along -axis, the field reentrant superconductivity is observed up to 35T, where the first order metamagnetic transition occurs. The NMR results have revealed unconventional magnetic and superconducting properties of this compound from a microscopic point of view.
Tokunaga, Yo
no journal, ,
NMR studies have been performed on a newly discovered heavy fermion superconductor UTe. Using a single crystal, we have successfully measured the NMR Knight shift and spin-lattice relaxation rate for fields along the three orthorhombic crystal axes. The data confirm a moderate Ising anisotropy for both the static and dynamical susceptibilities in the paramagnetic state above about 20 K. However, a divergence of the spin-spin relaxation rate observed below 20 K for H//a demonstrates the development of strong longitudinal magnetic fluctuations along the a-axis at very low frequency.
Tokunaga, Yo
no journal, ,
Te-NMR studies have been performed on a newly discovered heavy fermion superconductor UTe. Using a single crystal, we have measured the Te-NMR Knight shift and spin-lattice relaxation rate 
for fields along the three orthorhombic crystal axes. We confirmed a moderate Ising anisotropy for both the static and dynamical susceptibilities in the paramagnetic state above about 20 K. Around 20 K, however, we have observed a sudden loss of NMR spin-echo signal due to sudden enhancement of the NMR spin-spin relaxation rate 
, when the field is applied along the easy axis of magnetization. We have also performed NMR measurements on a single crystal which does not show superconductivity.
Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Opletal, P.; Tokiwa, Yoshifumi; Haga, Yoshinori; Fujibayashi, Hiroki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; et al.
no journal, ,
We report the results of Te NMR measurements in field () applied along the easy magnetization axis (the -axis). The experiments revealed slow electronic dynamics developing in the paramagnetic state of UTe. The observed slow fluctuations are concerned with a successive growth of long-range electronic correlations below 3040 K, where the spin susceptibility along the hard magnetization axis (the -axis) shows a broad maximum. The experiments also imply that tiny amounts of disorder or defects locally disturb the long-range electronic correlations and develop an inhomogeneous electronic state at low temperatures, leading to a low temperature upturn observed in the bulk-susceptibility in .
Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Haga, Yoshinori; Tokiwa, Yoshifumi; Opletal, P.; Fujibayashi, Hiroki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; et al.
no journal, ,
; NMR studyTokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Opletal, P.; Tokiwa, Yoshifumi; Haga, Yoshinori
no journal, ,
no abstracts in English
Sakai, Hironori; Opletal, P.; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Tokunaga, Yo; Kambe, Shinsaku; Haga, Yoshinori
no journal, ,
The superconducting transition temperature in the spin-triplet superconductor UTe increases from the initial reported value of 1.6 K to 2.0 K as the newly reported one improving the growth condition. We have developed a growth method for the superconductor UTe that is different from the usual chemical vapor phase transport method. As a result, we have succeeded in growing high-purity UTe crystals at 
=2.1 K and confirmed that the residual specific heat below is very low and the residual ratio of electrical resistance is very large. We report the optimization of the newly developed method for UTe.
-
phase diagram of spin-triplet superconducting UTeSakai, Hironori
no journal, ,
We have developed a single crystal growth method for UTe, which is attracting attention as a spin-triplet superconductor. With optimized growth conditions, the residual resistivity ratio has been significantly improved, in addition to an increase in superconducting transition temperature. The phase diagram of magnetic field ()-temperature () up to a high magnetic field of 25 T has been determined by simultaneous measurement of electrical resistivity and AC susceptibility using a high-quality single crystal grown by this method.
