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Journal Articles

Feedback of superconductivity on the magnetic excitation spectrum of UTe$$_{2}$$

Raymond, S.*; Knafo, W.*; Knebel, G.*; Kaneko, Koji; Brison, J.-P.*; Flouquet, J.*; Aoki, Dai*; Lapertot, G.*

Journal of the Physical Society of Japan, 90(11), p.113706_1 - 113706_5, 2021/11

Journal Articles

Low-dimensional antiferromagnetic fluctuations in the heavy-fermion paramagnetic ladder compound UTe$$_{2}$$

Knafo, W.*; Knebel, G.*; Steffens, P.*; Kaneko, Koji; Rosuel, A.*; Brison, J.-P.*; Flouquet, J.*; Aoki, Dai*; Lapertot, G.*; Raymond, S.*

Physical Review B, 104(10), p.L100409_1 - L100409_6, 2021/09

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

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:23.04(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

$$^{29}$$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

BB2015-1546.pdf:0.87MB

 Times Cited Count:1 Percentile:60.83

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:65.76

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

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:74.1(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

Fermi surface in the hidden-order state of URu$$_2$$Si$$_2$$ under intense pulsed magnetic fields up to 81T

Scheerer, G. W.*; Knafo, W.*; Aoki, Dai*; Nardone, M.*; Zitouni, A.*; B$'e$ard, J.*; Billette, J.*; Barata, J.*; Jaudet, C.*; Suleiman, M.*; et al.

Physical Review B, 89(16), p.165107_1 - 165107_12, 2014/04

 Times Cited Count:10 Percentile:47.27(Materials Science, Multidisciplinary)

Journal Articles

Anisotropic energy scale for degenerate Fermi and non-Fermi liquids near a quantum critical phase transition in YbRh$$_2$$Si$$_2$$

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

Physical Review B, 91(16), p.161110_1 - 161110_5, 2014/04

 Times Cited Count:3 Percentile:17.86(Materials Science, Multidisciplinary)

Based on $$^{29}$$Si nuclear spin-lattice relaxation time ($$T_1$$) data on a single crystal of YbRh$$_2$$Si$$_2$$, the coexisting Fermi liquid (FL) and non-Fermi liquid (NFL) states around the quantum critical phase transition have been found to be sensitive to the direction of the applied magnetic field. Augmented scaling analysis shows that the anisotropic characteristic temperature and field are roughly 10 times larger for $$Hparallel c$$ than for $$Hparallel a$$, consistent with a previously obtained anisotropic phase diagram.

Journal Articles

Magnetic polarization and Fermi surface instability; Case of YbRh$$_2$$Si$$_2$$

Pourret, A.*; Knebel, G.*; Matsuda, Tatsuma; Lapertot, G.*; Flouquet, J.*

Journal of the Physical Society of Japan, 82(5), p.053704_1 - 053704_5, 2013/05

 Times Cited Count:28 Percentile:81.38(Physics, Multidisciplinary)

Journal Articles

Observation of bulk band dispersions of YbRh$$_2$$Si$$_2$$ using soft X-ray angle-resolved photoemission spectroscopy

Yasui, Akira*; Saito, Yuji; Fujimori, Shinichi; kawasaki, Ikuto*; Okane, Tetsuo; Takeda, Yukiharu; Lapertot, G.*; Knebel, G.*; Matsuda, Tatsuma*; Haga, Yoshinori; et al.

Physical Review B, 87(7), p.075131_1 - 075131_6, 2013/02

 Times Cited Count:5 Percentile:28.48(Materials Science, Multidisciplinary)

We have performed soft X-ray angle-resolved photoemission spectroscopy (ARPES) measurements on YbRh$$_2$$Si$$_2$$ and clarified its three-dimensional bulk valence-band structures. The ARPES spectra have not only Yb$$^{3+}$$ multiplet peaks but also a finite contribution of Yb$$^{2+}$$ peaks at 15 K, corresponding to the valence fluctuating behavior in this compound. This means that Yb 4f electrons in this compound have itinerant character below the $$T_{rm K}$$. We have found that dispersions of the valence bands except the vicinity of the Yb 4f bands agree better with those of the band-structure calculation of LuRh$$_2$$Si$$_2$$ than those of YbRh$$_2$$Si$$_2$$ within a local-density approximation. In addition, the Yb 3d-4f resonant photoemission spectra of YbRh$$_2$$Si$$_2$$ strongly suggest the existence of Yb 5d electrons in the valence band. We conclude that the charge transfer from the Yb 4f state to the Yb 5d state has an important role in the formation of the valence band of YbRh$$_2$$Si$$_2$$.

Journal Articles

Field-induced phenomena in ferromagnetic superconductors UCoGe and URhGe

Aoki, Dai*; Taupin, M.*; Paulsen, C.*; Hardy, F.*; Taufour, V.*; Kotegawa, Hisashi*; Hassinger, E.*; Malone, L.*; Matsuda, Tatsuma; Miyake, Atsushi*; et al.

Journal of the Physical Society of Japan, 81(Suppl.B), p.SB002_1 - SB002_6, 2012/12

 Times Cited Count:3 Percentile:28.92(Physics, Multidisciplinary)

Journal Articles

High-field Fermi surface properties in the low-carrier heavy-fermion compound URu$$_2$$Si$$_2$$

Aoki, Dai*; Knebel, G.*; Sheikin, I.*; Hassinger, E.*; Malone, L.*; Matsuda, Tatsuma; Flouquet, J.*

Journal of the Physical Society of Japan, 81(7), p.074715_1 - 074715_6, 2012/07

 Times Cited Count:22 Percentile:75.43(Physics, Multidisciplinary)

Journal Articles

Reply to "Comment on 'Details of sample dependence and transport properties of URu$$_2$$Si$$_2$$'"

Matsuda, Tatsuma; Aoki, Dai*; Knebel, G.*; Haga, Yoshinori; Flouquet, J.*

Journal of the Physical Society of Japan, 81(5), p.056002_1 - 056002_2, 2012/05

 Times Cited Count:0 Percentile:0.14(Physics, Multidisciplinary)

This paper is a reply to the comment which was sent to our previous paper "Details of sample dependence and transport properties of URu$$_2$$Si$$_2$$" published November 2011 in Journal of the Physical Society of Japan.

Journal Articles

Details of sample dependence and transport properties of URu$$_2$$Si$$_2$$

Matsuda, Tatsuma; Hassinger, E.*; Aoki, Dai*; Taufour, V.*; Knebel, G.*; Tateiwa, Naoyuki; Yamamoto, Etsuji; Haga, Yoshinori; Onuki, Yoshichika; Fisk, Z.; et al.

Journal of the Physical Society of Japan, 80(11), p.114710_1 - 114710_10, 2011/11

 Times Cited Count:42 Percentile:86.3(Physics, Multidisciplinary)

Journal Articles

Ferromagnetic quantum critical endpoint in UCoAl

Aoki, Dai*; Combier, T.*; Taufour, V.*; Matsuda, Tatsuma; Knebel, G.*; Kotegawa, Hisashi*; Flouquet, J.*

Journal of the Physical Society of Japan, 80(9), p.094711_1 - 094711_10, 2011/09

 Times Cited Count:71 Percentile:92.29(Physics, Multidisciplinary)

Journal Articles

Thermoelectric evidence for high-field anomalies in the hidden order phase of URu$$_2$$Si$$_2$$

Malone, L.*; Matsuda, Tatsuma; Antunes, A.*; Knebel, G.*; Taufour, V.*; Aoki, Dai*; Behnia, K.*; Proust, C.*; Flouquet, J.*

Physical Review B, 83(24), p.245117_1 - 245117_5, 2011/06

 Times Cited Count:16 Percentile:59.6(Materials Science, Multidisciplinary)

Journal Articles

Pressure evolution of the magnetic field induced ferromagnetic fluctuation through the pseudo-metamagnetism of CeRu$$_2$$Si$$_2$$

Aoki, Dai*; Paulsen, C.*; Matsuda, Tatsuma; Malone, L.*; Knebel, G.*; Haen, P.*; Lejay, P.*; Settai, Rikio*; Onuki, Yoshichika; Flouquet, J.*

Journal of the Physical Society of Japan, 80(5), p.053702_1 - 053702_4, 2011/05

 Times Cited Count:17 Percentile:70.46(Physics, Multidisciplinary)

Journal Articles

Trends in heavy fermion matter

Flouquet, J.*; Aoki, Dai*; Bourdarot, F.*; Hardy, F.*; Hassinger, E.*; Knebel, G.*; Matsuda, Tatsuma; Maingast, C.*; Paulsen, C.*; Taufour, V.*

Journal of Physics; Conference Series, 273, p.012001_1 - 012001_25, 2011/02

 Times Cited Count:15 Percentile:96.43

Journal Articles

Inelastic contribution of the resistivity in the hidden order in URu$$_2$$Si$$_2$$

Hassinger, E.*; Matsuda, Tatsuma; Knebel, G.*; Taufour, V.*; Aoki, Dai*; Flouquet, J.*

Journal of Physics; Conference Series, 273, p.012031_1 - 012031_5, 2011/02

 Times Cited Count:2 Percentile:55.59

Journal Articles

First observation of quantum oscillations in the ferromagnetic superconductor UCoGe

Aoki, Dai*; Sheikin, I.*; Matsuda, Tatsuma; Taufour, V.*; Knebel, G.*; Flouquet, J.*

Journal of the Physical Society of Japan, 80(1), p.013705_1 - 013705_4, 2011/01

 Times Cited Count:31 Percentile:81.67(Physics, Multidisciplinary)

We succeeded in growing high quality single crystals of the ferromagnetic superconductor UCoGe and measured the magnetoresistance at fields up to 34 T. The Shubnikov-de Haas signal was observed for the first time in a U-111 system (UTGe, UTSi, T: transition metal). A small pocket Fermi surface ($$Fsim$$1 kT) with large cyclotron effective mass 25$$m_0$$ was detected at high fields above 22 T, implying that UCoGe is a low carrier system accompanied with heavy quasi-particles. The observed frequency decreases with increasing fields, indicating that the volume of detected Fermi surface changes nonlinearly with field. The cyclotron mass also decreases, which is consistent with the decrease of the $$A$$ coefficient of resistivity.

40 (Records 1-20 displayed on this page)