The Experts below are selected from a list of 2355 Experts worldwide ranked by ideXlab platform
Yuji Matsuda - One of the best experts on this subject based on the ideXlab platform.
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field induced quantum critical route to a fermi liquid in high temperature Superconductors
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: T Shibauchi, Yuji Matsuda, L Krusinelbaum, Masashi Hasegawa, Y Kasahara, Ryuji OkazakiAbstract:In high-transition-temperature (Tc) superconductivity, charge doping is a natural tuning parameter that takes copper oxides from the antiferromagnet to the superconducting region. In the metallic state above Tc, the standard Landau's Fermi-liquid theory of metals as typified by the temperature squared (T2) dependence of resistivity appears to break down. Whether the origin of the non-Fermi-liquid behavior is related to physics specific to the cuprates is a fundamental question still under debate. We uncover a transformation from the non-Fermi-liquid state to a standard Fermi-liquid state driven not by doping but by magnetic field in the overdoped high-Tc superconductor Tl2Ba2CuO6+x. From the c-axis resistivity measured up to 45 T, we show that the Fermi-liquid features appear above a sufficiently high field that decreases linearly with temperature and lands at a quantum critical point near the superconductivity's upper critical field—with the Fermi-liquid coefficient of the T2 dependence showing a power-law diverging behavior on the approach to the critical point. This field-induced quantum criticality bears a striking resemblance to that in quasi-two-dimensional Heavy-Fermion Superconductors, suggesting a common underlying spin-related physics in these Superconductors with strong electron correlations.
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fulde ferrell larkin ovchinnikov state in Heavy Fermion Superconductors
Journal of the Physical Society of Japan, 2007Co-Authors: Yuji Matsuda, Hiroshi ShimaharaAbstract:The Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state is a novel superconducting state in a strong magnetic field characterized by the formation of Cooper pairs with nonzero total momentum ( k ↑,- k + ...
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fulde ferrell larkin ovchinnikov state in Heavy Fermion Superconductors
arXiv: Superconductivity, 2007Co-Authors: Yuji Matsuda, Hiroshi ShimaharaAbstract:The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is a novel superconducting state in a strong magnetic field characterized by the formation of Cooper pairs with nonzero total momentum (k \uparrow, -k+q \downarrow), instead of the ordinary BCS pairs (k \uparrow, -k \downarrow). A fascinating aspect of the FFLO state is that it exhibits inhomogeneous superconducting phases with a spatially oscillating order parameter and spin polarization. The FFLO state has been of interest in various research fields, not only in Superconductors in solid state physics, but also in neutral Fermion superfluid of ultracold atomic gases and in color superconductivity in high energy physics. In spite of extensive studies of various Superconductors, there has been no undisputed experimental verification of the FFLO state, mainly because of the very stringent conditions required of the superconducting materials. Among several classes of materials, certain Heavy Fermion and organic Superconductors are believed to provide conditions that are favorable to the formation of the FFLO state. This review presents recent experimental and theoretical developments of the FFLO state mainly in Heavy Fermion Superconductors. In particular we address the recently discovered quasi-two-dimensional superconductor CeCoIn_5, which is a strong candidate for the formation of the FFLO state.
S Vieira - One of the best experts on this subject based on the ideXlab platform.
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imaging superconducting vortex cores and lattices with a scanning tunneling microscope
Superconductor Science and Technology, 2014Co-Authors: H Suderow, Isabel Guillamon, J G Rodrigo, S VieiraAbstract:The observation of vortices in Superconductors was a major breakthrough in developing the conceptual background for superconducting applications. Each vortex carries a flux quantum, and the magnetic field decreases radially from the center. Techniques used to make magnetic field maps, such as magnetic decoration, give vortex lattice images in a variety of systems. However, strong type II Superconductors allow penetration of the magnetic field over large distances, of the order of the magnetic penetration depth λ. Superconductivity survives up to magnetic fields where, for imaging purposes, there is no magnetic contrast at all. Static and dynamic properties of vortices are largely unknown at such high magnetic fields. Reciprocal space studies using neutron scattering have been employed to obtain insight into the collective behavior. But the microscopic details of vortex arrangements and their motion remain difficult to obtain. Direct real-space visualization can be made using scanning tunneling microscopy and spectroscopy (STM/S). Instead of using magnetic contrast, the electronic density of states describes spatial variations of the quasiparticle and pair wavefunction properties. These are of the order of the superconducting coherence length ξ, which is much smaller than λ. In principle, individual vortices can be imaged using STM up to the upper critical field where vortex cores, of size ξ, overlap. In this review, we describe recent advances in vortex imaging made with scanning tunneling microscopy and spectroscopy. We introduce the technique and discuss vortex images that reveal the influence of the Fermi surface distribution of the superconducting gap on the internal structure of vortices, the collective behavior of the lattice in different materials and conditions, and the observation of vortex lattice melting. We consider challenging lines of work, which include imaging vortices in nanostructures, multiband and Heavy Fermion Superconductors, single layers and van der Waals crystals, studying current-driven dynamics and the liquid vortex phases.
Yifeng Yang - One of the best experts on this subject based on the ideXlab platform.
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High-energy magnetic excitations from Heavy quasiparticles in CeCu2Si2
'Springer Science and Business Media LLC', 2021Co-Authors: Yu Song, Yifeng Yang, Weiyi Wang, Chongde Cao, Zahra Yamani, Yutao Sheng, Wolfgang Löser, Yiming Qiu, Robert J. BirgeneauAbstract:Abstract Magnetic fluctuations is the leading candidate for pairing in cuprate, iron-based, and Heavy Fermion Superconductors. This view is challenged by the recent discovery of nodeless superconductivity in CeCu2Si2, and calls for a detailed understanding of the corresponding magnetic fluctuations. Here, we mapped out the magnetic excitations in superconducting (S-type) CeCu2Si2 using inelastic neutron scattering, finding a strongly asymmetric dispersion for E ≲ 1.5 meV, which at higher energies evolves into broad columnar magnetic excitations that extend to E ≳ 5 meV. While low-energy magnetic excitations exhibit marked three-dimensional characteristics, the high-energy magnetic excitations in CeCu2Si2 are almost two-dimensional, reminiscent of paramagnons found in cuprate and iron-based Superconductors. By comparing our experimental findings with calculations in the random-phase approximation,we find that the magnetic excitations in CeCu2Si2 arise from quasiparticles associated with its Heavy electron band, which are also responsible for superconductivity. Our results provide a basis for understanding magnetism and superconductivity in CeCu2Si2, and demonstrate the utility of neutron scattering in probing band renormalization in Heavy Fermion metals
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a phenomenological theory of Heavy Fermion superconductivity in cecoin 5
Chinese Science Bulletin, 2017Co-Authors: Yifeng YangAbstract:Unconventional superconductivity was first discovered in Heavy Fermion materials which exhibit a rich variety of superconducting quantum phenomena. Understanding the microscopic origin of Heavy Fermion superconductivity will help us understand the nature of high-temperature superconductivity and explore new class of unconventional Superconductors. In this article, we give a brief introduction to the recent theoretical and experimental studies on Heavy Fermion Superconductors. In particular, it has been shown that previous understandings of the pairing mechanism based on oversimplified single-band model calculations may not explain the recent experimental observations of the superconducting gap symmetry and therefore need to be revisited. For example, the Heavy Fermion Superconductors CeCu2Si2 and UBe13, which have long been believed to have nodal superconducting gap structures for over three decades, are now found to exhibit nodeless behaviors in many new experiments. While these may be partially explained by using realistic band structures in combination with random phase approximation (RPA) for the dynamic susceptibility, we point out that for strongly correlated systems such as Heavy Fermions, RPA fails to capture the true behavior of quantum critical fluctuations which act as the pairing force for the unconventional superconductivity. We argue that there are three major issues that need to be taken into account in order to develop a good understanding of the Heavy Fermion superconductivity: (1) the strong electronic correlations and the two-fluid behavior of the f electrons; (2) the quantum critical nature of the superconducting pairing force that cannot be obtained based on RPA; (3) the multi-band or multi-orbital properties that rely on real materials and may be crucial for the gap structures. Following these considerations, we propose a new framework based on the strong-coupling Eliashberg theory that combines previous phenomenological theory of the spin-fluctuation-induced pairing mechanism and realistic band structures from either experimental measurements or first-principles calculations. As an example, we apply our model to the prototype Heavy Fermion Superconductors CeCoIn5 and CeRhIn5. By using a single-band model derived from the scanning tunneling spectroscopy, we solve the linearized Eliashberg equation and produce the correct d-wave superconducting gap structure, in agreement with experimental observations. We further predict a simple formula for the superconducting transition temperature T c as a function of the pairing strength and the spin fluctuation energy. We then extend the formula to general cases and use the two-fluid prediction on the Heavy electron density of states to calculate the pressure-variation of T c. Our results agree well with experiment and explain the dome structure of T c. For multi-band systems, we have studied the superconductivity in CeCu2Si2. In contrast to previous calculations that predict either d-wave or nodal s-wave gap, we found that the inter-band scattering plays an essential role and may cause a nodeless gap structure. This work is still under progress. We believe that the success of the new framework suggests that it may provide a promising basis for treating the above issues and will help our understanding of the properties of Heavy Fermion superconductivity. In the future, we hope to extend our study to other Heavy Fermion Superconductors and take into consideration the detailed orbital characters and the dual nature of f electrons. The latter would possibly require a reformulation of the Eliashberg equations.
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universal linear temperature resistivity possible quantum diffusion transport in strongly correlated Superconductors
Scientific Reports, 2017Co-Authors: Y H Liu, Hong Xiao, Yifeng YangAbstract:The strongly correlated electron fluids in high temperature cuprate Superconductors demonstrate an anomalous linear temperature (T) dependent resistivity behavior, which persists to a wide temperature range without exhibiting saturation. As cooling down, those electron fluids lose the resistivity and condense into the superfluid. However, the origin of the linear-T resistivity behavior and its relationship to the strongly correlated superconductivity remain a mystery. Here we report a universal relation [Formula: see text], which bridges the slope of the linear-T-dependent resistivity (dρ/dT) to the London penetration depth λ L at zero temperature among cuprate superconductor Bi2Sr2CaCu2O8+δ and Heavy Fermion Superconductors CeCoIn5, where μ 0 is vacuum permeability, k B is the Boltzmann constant and ħ is the reduced Planck constant. We extend this scaling relation to different systems and found that it holds for other cuprate, pnictide and Heavy Fermion Superconductors as well, regardless of the significant differences in the strength of electronic correlations, transport directions, and doping levels. Our analysis suggests that the scaling relation in strongly correlated Superconductors could be described as a hydrodynamic diffusive transport, with the diffusion coefficient (D) approaching the quantum limit D ~ ħ/m*, where m* is the quasi-particle effective mass.
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universal linear temperature resistivity possible quantum diffusion transport in strongly correlated Superconductors
arXiv: Superconductivity, 2017Co-Authors: Y H Liu, Hong Xiao, Yifeng YangAbstract:The strongly correlated electron fluids in high temperature cuprate Superconductors demonstrate an anomalous linear temperature ($T$) dependent resistivity behavior, which persists to a wide temperature range without exhibiting saturation. As cooling down, those electron fluids lose the resistivity and condense into the superfluid. However, the origin of the linear-$T$ resistivity behavior and its relationship to the strongly correlated superconductivity remain a mystery. Here we report a universal relation $d\rho/dT=(\mu_0k_B/\hbar)\lambda^2_L$, which bridges the slope of the linear-$T$-dependent resistivity ($d\rho/dT$) to the London penetration depth $\lambda_L$ at zero temperature among cuprate superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ and Heavy Fermion Superconductors CeCoIn$_5$, where $\mu_0$ is vacuum permeability, $k_B$ is the Boltzmann constant and $\hbar$ is the reduced Planck constant. We extend this scaling relation to different systems and found that it holds for other cuprate, pnictide and Heavy Fermion Superconductors as well, regardless of the significant differences in the strength of electronic correlations, transport directions, and doping levels. Our analysis suggests that the scaling relation in strongly correlated Superconductors could be described as a hydrodynamic diffusive transport, with the diffusion coefficient ($D$) approaching the quantum limit $D\sim\hbar/m^*$, where $m^*$ is the quasi-particle effective mass.
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Universal linear-temperature resistivity: possible quantum diffusion transport in strongly correlated Superconductors
'Springer Science and Business Media LLC', 2017Co-Authors: Yinshang Liu, Hong Xiao, Yifeng YangAbstract:Abstract The strongly correlated electron fluids in high temperature cuprate Superconductors demonstrate an anomalous linear temperature (T) dependent resistivity behavior, which persists to a wide temperature range without exhibiting saturation. As cooling down, those electron fluids lose the resistivity and condense into the superfluid. However, the origin of the linear-T resistivity behavior and its relationship to the strongly correlated superconductivity remain a mystery. Here we report a universal relation $$d{\boldsymbol{\rho }}/{\boldsymbol{dT}}=({{\boldsymbol{\mu }}}_{{\bf{0}}}{{\boldsymbol{k}}}_{{\boldsymbol{B}}}/{\boldsymbol{\hslash }})\,{{\boldsymbol{\lambda }}}_{{\boldsymbol{L}}}^{{\bf{2}}}$$ d ρ / dT = ( μ 0 k B / ℏ ) λ L 2 , which bridges the slope of the linear-T-dependent resistivity (dρ/dT) to the London penetration depth λ L at zero temperature among cuprate superconductor Bi2Sr2CaCu2O8+δ and Heavy Fermion Superconductors CeCoIn5, where μ 0 is vacuum permeability, k B is the Boltzmann constant and ħ is the reduced Planck constant. We extend this scaling relation to different systems and found that it holds for other cuprate, pnictide and Heavy Fermion Superconductors as well, regardless of the significant differences in the strength of electronic correlations, transport directions, and doping levels. Our analysis suggests that the scaling relation in strongly correlated Superconductors could be described as a hydrodynamic diffusive transport, with the diffusion coefficient (D) approaching the quantum limit D ~ ħ/m*, where m* is the quasi-particle effective mass
Y ōnuki - One of the best experts on this subject based on the ideXlab platform.
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magnetic field and pressure phase diagrams of uranium Heavy Fermion compound u2zn17
Journal of the Physical Society of Japan, 2011Co-Authors: Naoyuki Tateiwa, Shugo Ikeda, Yoshinori Haga, Tatsuma D Matsuda, Etsuji Yamamoto, Kiyohiro Sugiyama, M Hagiwara, Koichi Kindo, Y ōnukiAbstract:We have performed magnetization measurements at high magnetic fields of up to 53 T on single crystals of a uranium Heavy-Fermion compound U 2 Zn 17 grown by the Bridgman method. In the antiferromagnetic state below the Neel temperature T N =9.7 K, a metamagnetic transition is found at H c ≃32 T for the field along the [11\bar20] direction ( a -axis). The magnetic phase diagram for the field along the [11\bar20] direction is given. The magnetization curve shows a nonlinear increase at H m ≃35 T in the paramagnetic state above T N up to a characteristic temperature T χmax where the magnetic susceptibility or electrical resistivity shows a maximum value. This metamagnetic behavior of the magnetization at H m is discussed in comparison with the metamagnetic magnetism of the Heavy-Fermion Superconductors UPt 3 , URu 2 Si 2 , and UPd 2 Al 3 . We have also carried out high-pressure resistivity measurement on U 2 Zn 17 using a diamond anvil cell up to 8.7 GPa. Noble gas argon was used as a pressure-transmitting m...
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238 u mossbauer study on the magnetic properties of uranium based Heavy Fermion Superconductors
Hyperfine Interactions, 2000Co-Authors: Satoshi Tsutsui, Yoshinori Haga, Etsuji Yamamoto, Y ōnuki, Masami Nakada, Saburo Nasu, T Honma, Hitoshi OhkuniAbstract:We have performed 238U Mossbauer spectroscopy of uranium-based Heavy Fermion Superconductors, UPd2Al3 and URu2Si2, in order to investigate their physical properties, mainly their magnetic properties. The slow relaxation of magnetic hyperfine interaction in a paramagnetic state and the static hyperfine field has been observed in an antiferromagnetic ordered state for each compound. The line-widths have maximum at their characteristic temperatures where their magnetic susceptibilities have maximum values.
Y H Liu - One of the best experts on this subject based on the ideXlab platform.
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universal linear temperature resistivity possible quantum diffusion transport in strongly correlated Superconductors
Scientific Reports, 2017Co-Authors: Y H Liu, Hong Xiao, Yifeng YangAbstract:The strongly correlated electron fluids in high temperature cuprate Superconductors demonstrate an anomalous linear temperature (T) dependent resistivity behavior, which persists to a wide temperature range without exhibiting saturation. As cooling down, those electron fluids lose the resistivity and condense into the superfluid. However, the origin of the linear-T resistivity behavior and its relationship to the strongly correlated superconductivity remain a mystery. Here we report a universal relation [Formula: see text], which bridges the slope of the linear-T-dependent resistivity (dρ/dT) to the London penetration depth λ L at zero temperature among cuprate superconductor Bi2Sr2CaCu2O8+δ and Heavy Fermion Superconductors CeCoIn5, where μ 0 is vacuum permeability, k B is the Boltzmann constant and ħ is the reduced Planck constant. We extend this scaling relation to different systems and found that it holds for other cuprate, pnictide and Heavy Fermion Superconductors as well, regardless of the significant differences in the strength of electronic correlations, transport directions, and doping levels. Our analysis suggests that the scaling relation in strongly correlated Superconductors could be described as a hydrodynamic diffusive transport, with the diffusion coefficient (D) approaching the quantum limit D ~ ħ/m*, where m* is the quasi-particle effective mass.
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universal linear temperature resistivity possible quantum diffusion transport in strongly correlated Superconductors
arXiv: Superconductivity, 2017Co-Authors: Y H Liu, Hong Xiao, Yifeng YangAbstract:The strongly correlated electron fluids in high temperature cuprate Superconductors demonstrate an anomalous linear temperature ($T$) dependent resistivity behavior, which persists to a wide temperature range without exhibiting saturation. As cooling down, those electron fluids lose the resistivity and condense into the superfluid. However, the origin of the linear-$T$ resistivity behavior and its relationship to the strongly correlated superconductivity remain a mystery. Here we report a universal relation $d\rho/dT=(\mu_0k_B/\hbar)\lambda^2_L$, which bridges the slope of the linear-$T$-dependent resistivity ($d\rho/dT$) to the London penetration depth $\lambda_L$ at zero temperature among cuprate superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ and Heavy Fermion Superconductors CeCoIn$_5$, where $\mu_0$ is vacuum permeability, $k_B$ is the Boltzmann constant and $\hbar$ is the reduced Planck constant. We extend this scaling relation to different systems and found that it holds for other cuprate, pnictide and Heavy Fermion Superconductors as well, regardless of the significant differences in the strength of electronic correlations, transport directions, and doping levels. Our analysis suggests that the scaling relation in strongly correlated Superconductors could be described as a hydrodynamic diffusive transport, with the diffusion coefficient ($D$) approaching the quantum limit $D\sim\hbar/m^*$, where $m^*$ is the quasi-particle effective mass.