3
3.0
Jun 30, 2018
06/18
by
L. Malone; Y. Mizukami; P. Walmsley; C. Putzke; S. Kasahara; T. Shibauchi; Y. Matsuda; A. Carrington
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We present a study of the superconducting gap structure in the iron-pnictide series BaFe2(As1-xPx)2. By measuring the variation of the specific heat as a function of temperature and magnetic field we are able to determine the number and Fermi surface location of the nodes in the superconducting gap. In particular, from measurements of the variation of the specific heat as the magnetic field is rotated in the ab plane of the sample we conclude that the nodes are in the [110] directions. Then...
Topics: Superconductivity, Condensed Matter
Source: http://arxiv.org/abs/1409.7523
4
4.0
Jun 29, 2018
06/18
by
S. Hosoi; K. Matsuura; K. Ishida; Hao Wang; Y. Mizukami; T. Watashige; S. Kasahara; Y. Matsuda; T. Shibauchi
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The importance of antiferromagnetic fluctuations are widely acknowledged in most unconventional superconductors. In addition, cuprates and iron pnictides often exhibit unidirectional (nematic) electronic correlations, including stripe and orbital orders, whose fluctuations may also play a key role for electron pairing. However, these nematic correlations are intertwined with antiferromagnetic or charge orders, preventing us to identify the essential role of nematic fluctuations. This calls for...
Topics: Superconductivity, Condensed Matter, Materials Science, Strongly Correlated Electrons
Source: http://arxiv.org/abs/1604.00184
101
101
Jul 20, 2013
07/13
by
K. Hashimoto; S. Kasahara; R. Katsumata; Y. Mizukami; M. Yamashita; H. Ikeda; T. Terashima; A. Carrington; Y. Matsuda; T. Shibauchi
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High-precision measurements of magnetic penetration depth $\lambda$ in clean single crystals of LiFeAs and LiFeP superconductors reveal contrasting low-energy quasiparticle excitations. In LiFeAs the low-temperature $\lambda(T)$ shows a flat dependence indicative of a fully gapped state, which is consistent with previous studies. In contrast, LiFeP exhibits a $T$-linear dependence of superfluid density $\propto \lambda^{-2}$, indicating a nodal superconducting order parameter. A systematic...
Source: http://arxiv.org/abs/1107.4505v1
74
74
Sep 20, 2013
09/13
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S. Kasahara; H. J. Shi; K. Hashimoto; S. Tonegawa; Y. Mizukami; T. Shibauchi; K. Sugimoto; T. Fukuda; T. Terashima; Andriy H. Nevidomskyy; Y. Matsuda
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Strongly interacting electrons can exhibit novel collective phases, among which the electronic nematic phases are perhaps the most surprising as they spontaneously break rotational symmetry of the underlying crystal lattice. The electron nematicity has been recently observed in the iron-pnictide and cuprate high-temperature superconductors. Whether such a tendency of electrons to self-organise unidirectionally has a common feature in these superconductors is, however, a highly controversial...
Source: http://arxiv.org/abs/1207.1045v1
5
5.0
Jun 28, 2018
06/18
by
Y. Mizukami; Y. Kawamoto; Y. Shimoyama; S. Kurata; H. Ikeda; T. Wolf; D. A. Zocco; K. Grube; H. v. Löhneysen; Y. Matsuda; T. Shibauchi
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In the heavily hole-doped iron-based superconductors $A$Fe$_2$As$_2$ ($A=$ K, Rb, and Cs), the electron effective mass increases rapidly with alkali-ion radius. To study how the mass enhancement affects the superconducting state, we measure the London penetration depth $\lambda(T)$ in clean crystals of $A$Fe$_2$As$_2$ down to low temperature $T\sim0.1$ K. In all systems, the superfluid stiffness $\rho_s(T)=\lambda^2(0)/\lambda^2(T)$ can be approximated by a power-law $T$ dependence at low...
Topics: Superconductivity, Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1510.02273
46
46
Sep 20, 2013
09/13
by
S. K. Goh; Y. Mizukami; H. Shishido; D. Watanabe; S. Yasumoto; M. Shimozawa; M. Yamashita; T. Terashima; Y. Yanase; T. Shibauchi; A. I. Buzdin; Y. Matsuda
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We report a highly unusual angular variation of the upper critical field (H_c2) in epitaxial superlattices CeCoIn_5(n)/YbCoIn_5(5), formed by alternating layers of n and a 5 unit-cell thick heavy-fermion superconductor CeCoIn_5 with a strong Pauli effect and normal metal YbCoIn_5, respectively. For the n=3 superlattice, H_{c2}(\theta) changes smoothly as a function of the field angle \theta. However, close to the superconducting transition temperature, H_{c2}(\theta) exhibits a cusp near the...
Source: http://arxiv.org/abs/1207.4889v2
3
3.0
Jun 30, 2018
06/18
by
Y. Mizukami; M. Konczykowski; Y. Kawamoto; S. Kurata; S. Kasahara; K. Hashimoto; V. Mishra; A. Kreisel; Y. Wang; P. J. Hirschfeld; Y. Matsuda; T. Shibauchi
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In superconductors with unconventional pairing mechanisms, the energy gap in the excitation spectrum often has nodes, which allow quasiparticle excitations at low energies. In many cases, e.g. $d$-wave cuprate superconductors, the position and topology of nodes are imposed by the symmetry, and thus the presence of gapless excitations is protected against disorder. Here we report on the observation of distinct changes in the gap structure of iron-pnictide superconductors with increasing impurity...
Topics: Superconductivity, Condensed Matter
Source: http://arxiv.org/abs/1405.6951
3
3.0
Jun 30, 2018
06/18
by
M. Shimozawa; S. K. Goh; R. Endo; R. Kobayashi; T. Watashige; Y. Mizukami; H. Ikeda; H. Shishido; Y. Yanase; T. Terashima; T. Shibauchi; Y. Matsuda
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By using a molecular beam epitaxy technique, we fabricate a new type of superconducting superlattices with controlled atomic layer thicknesses of alternating blocks between heavy fermion superconductor CeCoIn_5, which exhibits a strong Pauli pair-breaking effect, and nonmagnetic metal YbCoIn_5. The introduction of the thickness modulation of YbCoIn_5 block layers breaks the inversion symmetry centered at the superconducting block of CeCoIn_5. This configuration leads to dramatic changes in the...
Topics: Superconductivity, Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1404.0482
45
45
Sep 22, 2013
09/13
by
K. Hashimoto; Y. Mizukami; R. Katsumata; H. Shishido; M. Yamashita; H. Ikeda; Y. Matsuda; J. A. Schlueter; J. D. Fletcher; A. Carrington; D. Gnida; D. Kaczorowski; T. Shibauchi
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When a second-order magnetic phase transition is tuned to zero temperature by a non-thermal parameter, quantum fluctuations are critically enhanced, often leading to the emergence of unconventional superconductivity. In these `quantum critical' superconductors it has been widely reported that the normal-state properties above the superconducting transition temperature $T_c$ often exhibit anomalous non-Fermi liquid behaviors and enhanced electron correlations. However, the effect of these strong...
Source: http://arxiv.org/abs/1302.2945v1
3
3.0
Jun 30, 2018
06/18
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S. Tonegawa; S. Kasahara; T. Fukuda; K. Sugimoto; N. Yasuda; Y. Tsuruhara; D. Watanabe; Y. Mizukami; Y. Haga; T. D. Matsuda; E. Yamamoto; Y. Onuki; H. Ikeda; Y. Matsuda; T. Shibauchi
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Since the 1985 discovery of the phase transition at $T_{\rm HO}=17.5$ K in the heavy-fermion metal URu$_2$Si$_2$, neither symmetry change in the crystal structure nor magnetic ordering have been observed, which makes this "hidden order" enigmatic. Some high-field experiments have suggested electronic nematicity which breaks fourfold rotational symmetry, but direct evidence has been lacking for its ground state at zero magnetic field. Here we report on the observation of lattice...
Topics: Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1406.5040
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40
Sep 23, 2013
09/13
by
P. Walmsley; C. Putzke; L. Malone; I. Guillamon; D. Vignolles; C. Proust; S. Badoux; A. I. Coldea; M. D. Watson; S. Kasahara; Y. Mizukami; T. Shibauchi; Y. Matsuda; A. Carrington
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We report a combined study of the specific heat and de Haas-van Alphen effect in the iron-pnictide superconductor BaFe$_2$(As$_{1-x}$P$_x$)$_2$. Our data when combined with results for the magnetic penetration depth give compelling evidence for the existence of a quantum critical point (QCP) close to $x=0.30$ which affects the majority of the Fermi surface by enhancing the quasiparticle mass. The results show that the sharp peak in the inverse superfluid density seen in this system results from...
Source: http://arxiv.org/abs/1303.3396v2
5
5.0
Jun 30, 2018
06/18
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S. Kasahara; T. Watashige; T. Hanaguri; Y. Kohsaka; T. Yamashita; Y. Shimoyama; Y. Mizukami; R. Endo; H. Ikeda; K. Aoyama; T. Terashima; S. Uji; T. Wolf; H. v. Löhneysenn; T. Shibauchi; Y. Matsuda
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Fermi systems in the crossover regime between weakly coupled Bardeen-Cooper-Schrieffer (BCS) and strongly coupled Bose-Einstein-condensate (BEC) limits are among the most fascinating objects to study the behavior of an assembly of strongly interacting particles. The physics of this crossover has been of considerable interest both in the fields of condensed matter and ultracold atoms. One of the most challenging issue in this regime is the effect of large spin imbalance on a Fermi system under...
Topics: Quantum Gases, Superconductivity, Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1411.1232
5
5.0
Jun 30, 2018
06/18
by
C. Putzke; P. Walmsley; J. D. Fletcher; L. Malone; D. Vignolles; C. Proust; S. Badoux; P. See; H. E. Beere; D. A. Ritchie; S. Kasahara; Y. Mizukami; T. Shibauchi; Y. Matsuda; A. Carrington
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Fluctuations around an antiferromagnetic quantum critical point (QCP) are believed to lead to unconventional superconductivity and in some cases to high-temperature superconductivity. However, the exact mechanism by which this occurs remains poorly understood. The iron-pnictide superconductor BaFe$_2$(As$_{1-x}$P$_x$)$_2$ is perhaps the clearest example to date of a high temperature quantum critical superconductor, and so it is a particularly suitable system in which to study how the quantum...
Topics: Superconductivity, Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1402.1323
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50
Sep 23, 2013
09/13
by
K. Hashimoto; K. Cho; T. Shibauchi; S. Kasahara; Y. Mizukami; R. Katsumata; Y. Tsuruhara; T. Terashima; H. Ikeda; M. A. Tanatar; H. Kitano; N. Salovich; R. W. Giannetta; P. Walmsley; A. Carrington; R. Prozorov; Y. Matsuda
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In a superconductor, the ratio of the carrier density, $n$, to their effective mass, $m^*$, is a fundamental property directly reflecting the length scale of the superfluid flow, the London penetration depth, $\lambda_L$. In two dimensional systems, this ratio $n/m^*$ ($\sim 1/\lambda_L^2$) determines the effective Fermi temperature, $T_F$. We report a sharp peak in the $x$-dependence of $\lambda_L$ at zero temperature in clean samples of BaFe$_2$(As$_{1-x}$P$_x$)$_2$ at the optimum composition...
Source: http://arxiv.org/abs/1212.5632v1
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20
Jun 28, 2018
06/18
by
J. P. Sun; K. Matsuura; G. Z. Ye; Y. Mizukami; M. Shimozawa; K. Matsubayashi; M. Yamashita; T. Watashige; S. Kasahara; Y. Matsuda; J. -Q. Yan; B. C. Sales; Y. Uwatoko; J. -G. Cheng; T. Shibauchi
texts
eye 20
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The coexistence and competition between superconductivity and electronic orders, such as spin or charge density waves, have been a central issue in high transition-temperature (${T_{\rm c}}$) superconductors. Unlike other iron-based superconductors, FeSe exhibits nematic ordering without magnetism whose relationship with its superconductivity remains unclear. More importantly, a pressure-induced fourfold increase of ${T_{\rm c}}$ has been reported, which poses a profound mystery. Here we report...
Topics: Superconductivity, Materials Science, Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1512.06951
