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Two-component uniform spin susceptibility in superconducting HgBa$_{2}$CuO$_{4+δ}$ single crystals determined with $^{63}$Cu and $^{199}$Hg NMR: $^{63}$Cu and $^{199}$Hg NMR shifts for an optimally and underdoped HgBa$_{2}$CuO$_{4+\delta}$ single crystal are reported, and the temperature dependence dictates a two-c...
cond-mat_supr-con
Fifty years of Hubbard and Anderson lattice models: from magnetism to unconventional superconductivity - A brief overview: We briefly overview the importance of Hubbard and Anderson-lattice models as applied to explanation of high-temperature and heavy-fermion superconductivity. Application of the models during the l...
cond-mat_supr-con
Doping Dependence of Anisotropic Resistivities in Trilayered Superconductor Bi2Sr2Ca2Cu3O10+delta (Bi-2223): The doping dependence of the themopower, in-plane resistivity rho_ab(T), out-of-plane resistivity rho_c(T), and susceptibility has been systematically measured for high-quality single crystal Bi2Sr2Ca2Cu3O10+d...
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Comparative study on the thermoelectric effect of parent oxypnictides La$T$AsO ($T$ = Fe, Ni): The thermopower and Nernst effect were investigated for undoped parent compounds LaFeAsO and LaNiAsO. Both thermopower and Nernst signal in iron-based LaFeAsO are significantly larger than those in nickel-based LaNiAsO. Fur...
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Structure and Composition of the 200 K-Superconducting Phase of H2S under Ultrahigh Pressure: The Perovskite (SH-)(H3S+): H2S is converted under ultrahigh pressure (> 110 GPa) to a metallic phase that becomes superconducting with a record Tc of 200 K. It has been proposed that the superconducting phase is body-center...
cond-mat_supr-con
Superconductivity in boron-doped carbon nanotube networks: By using the five Angstrom diameter pores of calcined zeolite as the template, we have fabricated boron doped carbon nanotube networks via the chemical vapor deposition method. Raman data indicate the network to comprise segments of interconnected carbon nano t...
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Quantum phase-slips in Josephson junction rings: We study quantum phase-slip (QPS) processes in a superconducting ring containing N Josephson junctions and threaded by an external static magnetic flux. In a such system, a QPS consists of a quantum tunneling event connecting two distinct classical states of the phases w...
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Characterization of the superconducting phase in tellurium hydride at high pressure: At present, hydrogen-based compounds constitute one of the most promising classes of materials for applications as a phonon-mediated high-temperature superconductors. Herein, the behavior of the superconducting phase in tellurium hyd...
cond-mat_supr-con
Probing pair-breaking mechanisms in proximity-induced hybrid superconducting interfaces: Understanding depairing effects in a hybrid-superconducting interface utilizing high spin-orbit materials such as topological insulators or 1D semiconducting nanowires is becoming an important research topic in the study of proxi...
cond-mat_supr-con
Study of Local Nonlinear Properties Using a Near-Field Microwave Microscope: We have developed a near-field microwave microscope to locally apply microwave frequency currents and fields to superconductors, and dielectric substrates, and measure the locally generated 2nd and 3rd harmonic responses. We measure the loca...
cond-mat_supr-con
Superconductivity from site-selective Ru doping studies in Zr$_5$Ge$_3$ compound: Systematical doping studies have been carried out to search for the possible superconductivity in the transition metal doped Zr$_5$Ge$_3$ system. Superconductivity up to 5.7K is discovered in the Ru-doped Zr$_5$Ge$_{2.5}$Ru$_{0.5}$ samp...
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Extracting phase information about the superconducting order parameter from defect bound states: Impurity bound states and quasi-particle scattering from these can serve as sensitive probes for identifying the pairing state of a superconducting condensate. We introduce and discuss defect bound state quasi-particle in...
cond-mat_supr-con
Effective medium approximation and the complex optical properties of the inhomogeneous superconductor K_{0.8}Fe_{2-y}Se_2: The in-plane optical properties of the inhomogeneous iron-chalcogenide superconductor K_{0.8}Fe_{2-y}Se_2 with a critical temperature Tc = 31 K have been modeled in the normal state using the Bru...
cond-mat_supr-con
Flatband-Induced Itinerant Ferromagnetism in RbCo$_2$Se$_2$: $A$Co$_2$Se$_2$ ($A$=K,Rb,Cs) is a homologue of the iron-based superconductor, $A$Fe$_2$Se$_2$. From a comprehensive study of RbCo$_2$Se$_2$ via measurements of magnetization, transport, neutron diffraction, angle-resolved photoemission spectroscopy, and firs...
cond-mat_supr-con
Hidden charge-conjugation, parity, and time-reversal symmetries and massive Goldstone (Higgs) modes in superconductors: A massive Goldstone (MG) mode, often referred to as a Higgs amplitude mode, is a collective excitation that arises in a system involving spontaneous breaking of a continuous symmetry, along with a g...
cond-mat_supr-con
Quasiparticle conductance in Spin Valve Josephson Structures: We study the quasiparticle current in clean ferromagnetic Josephson structures of the form $S_1/F_1/N/F_2/S_2$, where $S$, $F$, and $N$ denote superconducting, ferromagnetic or normal layers respectively. Our focus is on the structure of the conductance $G$ ...
cond-mat_supr-con
Reverse Monte Carlo study of apical Cu-O bond distortions in YBa2Cu3O6.93: A combination of neutron total scattering measurement and reverse Monte Carlo (RMC) refinement is applied to the study of apical Cu-O bond distortions in the high-Tc superconductor YBa2Cu3O6.93. We show that the average structure is not consis...
cond-mat_supr-con
Evolution of vortex pinning in the FeSe$_{1-x}$S$_x$ system: We present a comprehensive study of vortex matter and pinning evolution in the FeSe$_{1-x}$S$_x$ system with various doping degree. The influence of sulphur substitution on vortex pinning and peak effect occurrence is studied. We show that there is a complex ...
cond-mat_supr-con
Elevated Tc levels in YBa2Cu3O6.5 modeled on a 3-dimensional doped bond structure of chain and plane pairs: The complex phenomenology of shot quenched YBa2Cu3O6.5 with Tc=100K and 200K levels is compared with laser pulsed analogs with an eye on explaining the presumed Tc=552K of the latter. Shot quenching can produce...
cond-mat_supr-con
Phases of Mott-Hubbard bilayers: A phase diagram of two Mott-Hubbard planes interacting with a short-range Coulomb repulsion is presented. Considering the case of equal amount of doping by holes in one layer as electrons in the other, a holon-doublon inter-layer exciton formation is shown to be a natural consequence of...
cond-mat_supr-con
Properties of the phonon-induced pairing interaction in YBa$_2$Cu$_3$O$_7$ within the local density approximation: The properties of the phonon-induced interaction between electrons are studied using the local density approximation (LDA). Restricting the electron momenta to the Fermi surface we find generally that th...
cond-mat_supr-con
Pressure induced metallization and possible unconventional superconductivity in spin liquid $NaYbSe_{2}$: Beyond the conventional electron pairing mediated by phonons, high-temperature superconductivity in cuprates is believed to stem from quantum spin liquid (QSL). The unconventional superconductivity by doping a sp...
cond-mat_supr-con
Weakly correlated electrons on a square lattice: a renormalization group theory: We study the weakly interacting Hubbard model on the square lattice using a one-loop renormalization group approach. The transition temperature T_c between the metallic and (nearly) ordered states is found. In the parquet regime, (T_c >>...
cond-mat_supr-con
Superconducting d-wave stripes in cuprates: Valence bond order coexisting with nodal quasiparticles: We point out that unidirectional bond-centered charge-density-wave states in cuprates involve electronic order in both s- and d-wave channels, with non-local Coulomb repulsion suppressing the s-wave component. The res...
cond-mat_supr-con
Andreev reflection observation in Nb/FeSi/Nb and Nb/FeSi/Si/Nb Josephson junctions: Electrical properties of Josephson junctions Nb/FeSi/Nb with superconductor/ferromagnet (S/F)interfaces are presented. Due to Andreev reflection the nearly exact quadruple enhancement of the tunnel junction differential conductance co...
cond-mat_supr-con
Time-Reversal-Symmetry-Broken Superconductivity Induced by Frustrated Inter-Component Couplings: Superconductivity is associated with spontaneously broken gauge symmetry. In some exotic superconductors the time-reversal symmetry is broken as well, accompanied with internal magnetic field. A time-reversal symmetry bro...
cond-mat_supr-con
Topological phase separation in 2D hard-core Bose-Hubbard system away from half-filling: We suppose that the doping of the 2D hard-core boson system away from half-filling may result in the formation of multi-center topological defect such as charge order (CO) bubble domain(s) with Bose superfluid (BS) and extra boso...
cond-mat_supr-con
Dislocation Majorana zero modes in perovskite oxide 2DEG: Much of the current experimental efforts for detecting Majorana zero modes have been centered on probing the boundary of quantum wires with strong spin-orbit coupling. The same type of Majorana zero mode can also be realized at crystalline dislocations in 2D sup...
cond-mat_supr-con
Dispersion of the odd magnetic resonant mode in near-optimally doped Bi2Sr2CaCu2O8+d: We report a neutron scattering study of the spin excitation spectrum in the superconducting state of slightly overdoped Bi2Sr2CaCu2O8+d system (Tc=87 K). We focus on the dispersion of the resonance peak in the superconducting state ...
cond-mat_supr-con
Mo$_{3}$ReRuC: A noncentrosymmetric superconductor formed in the MoReRu-Mo$_{2}$C system: A quaternary compound with the composition Mo$_{3}$ReRuC is obtained in a previously unexplored MoReRu-Mo$_{2}$C system. According to x-ray structural analysis, Mo$_{3}$ReRuC crystallizes in the noncentrosymmetric space group $P...
cond-mat_supr-con
Superconducting energy gap in $\rm Ba_{1-x}K_xBiO_3$: Temperature dependence: The superconducting energy gap of $\rm Ba_{1-x}K_xBiO_3$ has been measured by tunneling. Despite the fact that the sample was macroscopically single phase with very sharp superconducting transition $T_c$ at 32~$K$, some of the measured tunn...
cond-mat_supr-con
Stability Conditions in Gapless Superconductors: Gapless superconductivity can arise when pairing occurs between fermion species with different Fermi surface sizes, provided there is a sufficiently large mismatch between Fermi surfaces and/or at sufficiently large coupling constant. In gapless states, secondary Fermi s...
cond-mat_supr-con
Aharonov-Bohm Effect for Quasiparticles around a Vortex Line in a D-wave Superconductor: On the basis of the Bogolubov-de Gennes theory we develop an analytical description of low-energy extended quasiparticle states around an isolated flux line in a superconductor with gap nodes. The wavefunctions of these excitatio...
cond-mat_supr-con
Magnetic resonance in a singlet-triplet Josephson junction: We study a singlet-triplet Josephson junction between a conventional s-wave superconductor and an unconventional p$_{\rm x}$-wave superconductor. The Andreev spectrum of the junction yields a spontaneous magnetization in equilibrium. This allows manipulating t...
cond-mat_supr-con
Anomalous lattice expansion of RuSr2Eu1.5Ce0.5Cu2O10(Ru-1222) magneto superconductor: A low temperature X-ray diffraction study: This is the first report of the observation of the onset of excess volume and also of the strain along the a-axis near the magnetic ordering temperature in Ru-1222 superconductor, and indic...
cond-mat_supr-con
Thin Spectrum States in Superconductors: We show that finite size superconductors have a spectrum of states at extremely low energy, i.e. inside the superconducting gap. The presence of this {\it thin spectrum} is a generic feature and related to the fact that in a superconductor the global phase rotation symmetry is s...
cond-mat_supr-con
Multiorbital effects on the transport and the superconducting fluctuations in LiFeAs: The resistivity, Hall effect and transverse magnetoresistance (MR) have been measured in low residual resistivity single crystals of LiFeAs. A comparison with angle resolved photoemission spectroscopy and quantum oscillation data im...
cond-mat_supr-con
Temperature and field dependence of thermally activated flux flow resistance in Bi2Sr2CaCu2O8+δ superconductor: We study the temperature dependence of the resistivity as a function of magnetic field in superconducting transition (Tconset - TcR=0) region for different Bi2Sr2CaCu2O8+{\delta} superconducting samples bei...
cond-mat_supr-con
Continuous and reversible tuning of the disorder-driven superconductor-insulator transition in bilayer graphene: The influence of static disorder on a quantum phase transition (QPT) is a fundamental issue in condensed matter physics. As a prototypical example of a disorder-tuned QPT, the superconductor-insulator tran...
cond-mat_supr-con
The London moment: what a rotating superconductor reveals about superconductivity: The London moment is the magnetic moment acquired by a rotating superconductor. We propose that the London moment reveals the following fundamental properties of the superconducting state: (i) superconductors (unlike normal metals) kno...
cond-mat_supr-con
Superconductivity of Cobalt in Thin Films: Due to competing long range ferromagnetic order, the transition metals Fe, Co and Ni are not superconductors at ambient pressure. While superconductivity was observed in a non-magnetic phase of Fe, stabilized under pressure, it is yet to be discovered in Co and Ni under any ex...
cond-mat_supr-con
Exact solution of the Lawrence-Doniach model in parallel magnetic fields: For the first time, we obtain the complete and exact analytical solution of the Lawrence-Doniach model for layered superconductors in external parallel magnetic fields. By solving a nontrivial mathematical problem of exact minimization of the fre...
cond-mat_supr-con
Emergent phenomena in multicomponent superconductivity: an introduction to the focus issue: Multicomponent superconductivity is a novel quantum phenomenon in many different superconducting materials, such as multiband ones in which different superconducting gaps open in different Fermi surfaces, films engineered at t...
cond-mat_supr-con
Reduction of electron repulsion and enhancement of $T_{c}$ in small diffusive superconducting grains: The superconducting properties of small metallic grains has been a topic of active research for half a century now. Early experiments demonstrated a remarkable rise in the critical temperature, $T_{c}$, with reducing...
cond-mat_supr-con
Doping evoluton of antiferromagnetic order and structural distortion in LaFeAsO$_{1-x}$F$_x$: We use neutron scattering to study the structural distortion and antiferromagnetic (AFM) order in LaFeAsO$_{1-x}$F$_{x}$ as the system is doped with fluorine (F) to induce superconductivity. In the undoped state, LaFeAsO exh...
cond-mat_supr-con
The Berry curvature of the Bogoliubov quasiparticle Bloch states in the unconventional superconductor Sr$_2$RuO$_4$: We will extend the concept of electron band Berry curvatures to superconducting materials. We show that this can be defined for the Bogoliubov-de Gennes equation describing the superconducting state in...
cond-mat_supr-con
Field-driven transition in the Ba$_{1-x}$K$_x$Fe$_2$As$_2$ superconductor with splayed columnar defects: Through 2.6 GeV U irradiations, we have induced bimodal splayed columnar defects in Ba$_{1-x}$K$_x$Fe$_2$As$_2$ single crystals with splay angles, $\pm 5 ^\circ$, $\pm 10 ^\circ$, $\pm 15 ^\circ$, and $\pm 20 ^\ci...
cond-mat_supr-con
Ginzburg-Landau theory for the time-dependent phase field in a two-dimensional d-wave superconductor: We derive a finite temperature time-dependent effective theory for the phase $\theta$ of the pairing field, which is appropriate for a 2D conducting electron system with non-retarded d-wave attraction. As for s-wave ...
cond-mat_supr-con
Even Parity, Orbital Singlet and Spin Triplet Pairing for Superconducting $La(O_{1-x}F_x)FeAs$: In the present paper, we propose the parity even,orbital singlet and spin triplet pairing state as the ground state of the newly discovered super-conductor $LaO_{1-x}F_xFeAs$.The pairing mechanism involves both the special...
cond-mat_supr-con
Critical currents and vortex-unbinding transitions in quench-condensed ultrathin films of Bismuth and Tin: We have investigated the I-V characteristics of strongly disordered ultra-thin films of {\it Bi} and {\it Sn} produced by quench-condensation. Our results show that both these sytems can be visualized as strongl...
cond-mat_supr-con
Comment on `Strong Vortex Liquid Correlation' from Multiterminal Measurements on Untwinned YBa$_2$Cu$_3$O$_{7-δ}$ Single Crystals': A.Rydh and \"O.Rapp [Phys. Rev. Lett. {\bf 86}, 1873 (2001).] claim that the vortex liquid in untwinned YBa$_2$Cu$_3$O$_{7-\delta}$ crystals is correlated above the melting transition, i...
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Spin Excitation in d-wave Superconductors : A Fermi Liquid Picture: A detailed study of the Inelastic Neutron Scattering (INS) spectra of the high-$T_c$ cuprates based on the Fermi liquid (FL) picture is given. We focus on the issue of the transformation between the commensurate and incommensurate (IC) excitation drive...
cond-mat_supr-con
Cooper Pairing in A Doped 2D Antiferromagnet with Spin-Orbit Coupling: We study the two-dimensional Hubbard model with the Rashba type spin-orbit coupling within and beyond the mean-field theory. The antiferromagnetic ground state for the model at half-filling and the Cooper pairing induced by antiferromagnetic spin fl...
cond-mat_supr-con
Visualization of Electron Nematicity and Unidirectional Antiferroic Fluctuations at High Temperatures in NaFeAs: The driving forces behind electronic nematicity in the iron pnictides remain hotly debated. We use atomic-resolution variable-temperature scanning tunneling spectroscopy to provide the first direct visual ...
cond-mat_supr-con
Revisiting Anderson-Higgs mechanism: application of Lieb-Schultz-Mattis theorem: We consider an electron model of superconductivity on a three-dimensional lattice where there are on-site attractive Hubbard interaction and long-range repulsive Coulomb interaction. It is claimed that fully gapped $s$-wave superconducti...
cond-mat_supr-con
Unveiling the hidden nematicity and spin subsystem in FeSe: The nematic order (nematicity) is considered one of the essential ingredients to understand the mechanism of Fe-based superconductivity. In most Fe-based superconductors (pnictides), nematic order is reasonably close to the antiferromagnetic order. In FeSe, in...
cond-mat_supr-con
Impurity effects on the spin excitation spectra in a d-wave superconductor: The effects of nonmagnetic impurity on the spin excitation spectra in a $d_{x^2-y^2}$-wave superconductor are examined, using the self-consistent $t$-matrix approximation. It is shown that the impurity self-energy acts to shift the position o...
cond-mat_supr-con
Deviations from the extended London model at high magnetic fields in YBa$_2$Cu$_3$O$_7$: We report on the evolution with magnetic field and temperature of the vortex lattice (VL) in fully-oxygenated YBa2Cu3O7 as studied by time-of-flight small angle neutron scattering. Using the HFM/EXED beamline, we have obtained da...
cond-mat_supr-con
Organic Superconductors: when correlations and magnetism walk in: This survey provides a brief account for the start of organic superconductivity motivated by the quest for high Tc superconductors and its development since the eighties'. Besides superconductivity found in 1D organics in 1980, progresses in this field o...
cond-mat_supr-con
Normal State Nernst Effect in Electron-doped Pr2-xCexCuO4: Superconducting Fluctuations and Two-band Transport: We report a systematic study of normal state Nernst effect in the electron-doped cuprates Pr$_{2-x}$Ce$_x$CuO$_{4-\delta}$ over a wide range of doping (0.05$\leq x \leq$0.21) and temperature. At low tempera...
cond-mat_supr-con
An elastic lattice in a random potential: Using Monte Carlo simulations, we study the properties of an elastic triangular lattice subject to a random background potential. As the cooling rate is reduced, we observe a rather sudden crossover between two different glass phases, one with exponential decay of correlations,...
cond-mat_supr-con
High-pressure flux growth, structural, and superconducting properties of LnFeAsO (Ln = Pr, Nd, Sm) single crystals: Single crystals of the LnFeAsO (Ln1111, Ln = Pr, Nd, and Sm) family with lateral dimensions up to 1 mm were grown from NaAs and KAs flux at high pressure. The crystals are of good structural quality and...
cond-mat_supr-con
Absence of Cooper-type bound states in three- and few-electron systems: It is shown that the appearance of a fixed-point singularity in the kernel of the two-electron Cooper problem is responsible for the formation of the Cooper pair for an arbitrarily weak attractive interaction between two electrons. This singularity...
cond-mat_supr-con
Observation of the Nernst signal generated by fluctuating Cooper pairs: Long-range order is destroyed in a superconductor warmed above its critical temperature (Tc). However, amplitude fluctuations of the superconducting order parameter survive and lead to a number of well established phenomena such as paraconductivity...
cond-mat_supr-con
AC losses in macroscopic thin-walled superconducting niobium cylinders: Measurements of the ac response represent a widely-used method for probing the properties of superconductors. In the surface superconducting state (SSS), increase of the current beyond the surface critical current $I_c$ leads to breakdown of SSS an...
cond-mat_supr-con
Columnar defects acting as passive internal field detectors: We have studied the angular dependence of the irreversible magnetization of several YBa$_2$Cu$_3$O$_7$ and 2H-NbSe$_2$ single crystals with columnar defects tilted off the c-axis. At high magnetic fields, the irreversible magnetization $M_i(\Theta_H)$ exhibit...
cond-mat_supr-con
Roles of anisotropic and unequal gaps in the quasiparticle interference of superconducting iron pnictides: We investigate the role of gap characteristics such as anisotropy and inequality of the gaps in the quasiparticle interferences of iron pnictides using a five-orbital tight-binding model. We examine how the diff...
cond-mat_supr-con
Possible realization of an antiferromagnetic Griffiths phase in Ba[Fe(1-x)Mn(x)](2)As(2): We investigate magnetic ordering in metallic Ba[Fe(1-x)Mn(x)](2)As(2) and discuss the unusual magnetic phase, which was recently discovered for Mn concentrations x > 10%. We argue that it can be understood as a Griffiths-type ph...
cond-mat_supr-con
Superconductivity in High-Entropy-Alloy Telluride AgInSnPbBiTe5: A polycrystalline sample of the high-entropy-alloy-type telluride AgInSnPbBiTe5 was synthesized using high-pressure synthesis. Superconductivity with a transition temperature (Tc) of 2.6 K was observed in AgInSnPbBiTe5. Elemental and structural analyses r...
cond-mat_supr-con
Anomalous doping dependence of the fluctuation-induced diamagnetism in superconductors of YBCO family: SQUID magnetization measurements in oriented powders of Y$_{1-x}$Ca$_{x}$Ba$% _{2}$Cu$_{3}$O$_{y}$, with $x$ ranging from 0 to 0.2, for $y\approx 6.1$ and $y\approx 6.97$, have been performed in order to study the d...
cond-mat_supr-con
The Field Perturbation Theory of Pseudogaps in HTSC: Here I establish the field perturbation theory of pseudogaps in HTSC. The proposed ground state suggests an internal particle-hole field, which is normal to nesting surfaces, and having twice the Fermi wave-number. It is proved that the system violates momentum conse...
cond-mat_supr-con
Effect of superlattice modulation of electronic parameters on superconducting density of states in cuprate superconductors: Recent scanning tunneling microscopy on BSCCO 2212 has revealed a substantial spatial supermodulation of the energy gap in the superconducting state. We propose that this gap modulation is due t...
cond-mat_supr-con
Evidence for Pauli-limiting behaviour at high fields and enhanced upper critical fields near T_c in several disordered FeAs based Superconductors: We report resistivity and upper critical field B_c2(T) data for disordered (As deficient) LaO_0.9F_0.1FeAs_1-delta in a wide temperature and high field range up to 60 T. T...
cond-mat_supr-con
Microstructural and transport properties of superconducting FeTe0.65Se0.35 crystals: The issue concerning the nature and the role of microstructural inhomogeneities in iron chalcogenide superconducting crystals of FeTe0.65Se0.35 and their correlation with transport properties of this system was addressed. Presented d...
cond-mat_supr-con
Periodicity of magnetization reversals in $\varphi_0$ Josephson junction: The magnetization reversal in ${\varphi_0}$-Josephson junction with direct coupling between magnetic moment and Josephson current has been studied. By adding pulse signal, the dynamics of magnetic moment components have been simulated and the ful...
cond-mat_supr-con
Quantum vortex fluctuations in cuprate superconductors: We study the effects of quantum vortex fluctuations in two-dimensional superconductors using a dual theory of vortices, and investigate the relevance to underdoped cuprates where the superconductor-insulator transition (SIT) is possibly driven by quantum vortex pr...
cond-mat_supr-con
Energy gaps in high-$T_c$ superconductors: BCS after all?: A major impediment to solving the problem of high-$T_c$ superconductivity is the ongoing confusion about the magnitude, structure and doping dependence of the superconducting gap, $\Delta_0$, and of the mysterious pseudogap found in underdoped samples\cite{Tall...
cond-mat_supr-con
Stretched exponential spin relaxation in organic superconductors: Proton NMR measurements on the organic superconductor $\kappa-(ET)_2Cu[N(CN)_2]Br$ ($T_C = 11.6$ K) exhibit stretched exponential spin-lattice relaxation below $T\approx 25$ K, suggestive of an inhomogeneous magnetic phase that develops in the normal sta...
cond-mat_supr-con
Tunneling Studies of Pseudogaps: a Comment: Recent tunneling observations of a pseudogap in Bi_2Sr_2CaCu_2O_{8+delta} are not necessarily evidence that the pseudogap is associated with superconducting fluctuations. The data are here analyzed as a competition between superconductivity and a density wave (taken as a simp...
cond-mat_supr-con
Hole-Doped Room-Temperature Superconductivity in H$_{3}$S$_{1-x}$Z$_x$ (Z=C, Si): We examine the effects of the low-level substitution of S atoms by C and Si atoms on the superconductivity of H$_3$S with the $Im\bar{3}m$ structure at megabar pressure. The hole doping can fine-tune the Fermi energy to reach the electr...
cond-mat_supr-con
The Superfluid Glass Phase of 3He-A: It is established theoretically that an ordered state with continuous symmetry is inherently unstable to arbitrarily small amounts of disorder [1, 2]. This principle is of central importance in a wide variety of condensed systems including superconducting vortices [3, 4], Ising spin...
cond-mat_supr-con
Effective Vortex Pinning in MgB2 thin films: We discuss pinning properties of MgB2 thin films grown by pulsed-laser deposition (PLD) and by electron-beam (EB) evaporation. Two mechanisms are identified that contribute most effectively to the pinning of vortices in randomly oriented films. The EB process produces low de...
cond-mat_supr-con
Electronic structure, lattice dynamics and magnetism of new ThXAsN (X=Fe,Co,Ni) superconductors: A First Principles Study: In this work, we present a comparative first principles study of mechanical properties, electronic structure, phonon dispersion relation, electron-phonon coupling and magnetism in three isostruct...
cond-mat_supr-con
2D orbital-like magnetic order in ${\rm La_{2-x}Sr_xCuO_4}$: In high temperature copper oxides superconductors, a novel magnetic order associated with the pseudogap phase has been identified in two different cuprate families over a wide region of temperature and doping. We here report the observation below 120 K of a s...
cond-mat_supr-con
Tunable nodal kagome superconductivity in charge ordered RbV3Sb5: Unconventional superconductors often feature competing orders, small superfluid density, and nodal electronic pairing. While unusual superconductivity has been proposed in the kagome metals AV3Sb5, key spectroscopic evidence has remained elusive. Here we...
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The decrease of the critical current of coated conductors when a perpendicular magnetic field is applied : a Josephson effect point of view: A large decrease is observed in the critical current density of YBCO coated conductors (CC) and related compounds when a strong perpendicular magnetic field is applied. While me...
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In-Plane and Out-of-Plane Optical Properties of NdBa2Cu3Ox Single Crystals close to x = 7.0: We present results of reflectivity measurements with E parallel to c and E perpendicular to c on NdBa2Cu3Ox (Nd123) single crystals close to full oxygen doping. Along the c-axis the optical conductivity shows a well developed...
cond-mat_supr-con
Nesting, spin-fluctuations, and odd-gap superconductivity in NaxCoO2 yH2O: We have calculated the one-electron susceptibility of hydrated NaxCoO2 and find strong nesting nearly commensurate with a 2X2 superstructure. The nesting involves about 70% of all electrons at the Fermi level and is robust with respect to dopi...
cond-mat_supr-con
Probing the electron-phonon interaction in correlated systems with coherent lattice fluctuation spectroscopy: Tailoring the properties of correlated oxides is accomplished by chemical doping, pressure, temperature or magnetic field. Photoexcitation is a valid alternative to reach out-of-equilibrium states otherwise i...
cond-mat_supr-con
Superconductivity and unusual magnetic behavior in amorphous carbon: Traces of superconductivity (SC) at elevated temperatures (up to 65 K) were observed by magnetic measurements in three different inhomogeneous sulfur doped amorphous carbon (a-C) systems: (a) in commercial and (b) synthesized powders and (c) in a-C th...
cond-mat_supr-con
Nature of 45 degree vortex lattice reorientation in tetragonal superconductors: The transformation of the vortex lattice in a tetragonal superconductor which consists of its 45 degree reorientation relative to the crystal axes is studied using the nonlocal London model. It is shown that the reorientation occurs as tw...
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Possible Triplet Superconducting Order in Magnetic Superconducting Phase induced by Paramagnetic Pair-Breaking: Motivated by recent thermal conductivity measurements in the superconductor CeCoIn5, we theoretically examine a possible staggered spin-triplet superconducting order to be induced by the coupled spin-densit...
cond-mat_supr-con
Half-quantum vortex and d-soliton in Sr$_2$RuO$_4$: Assuming that the superconductivity in Sr$_2$RuO$_4$ is described by a planar p-wave order parameter, we consider possible topological defects in Sr$_2$RuO$_4$. In particular, it is shown that both of the ${\hat d}$-soliton and half-quantum vortex can be created in th...
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Uniaxial "nematic-like" electronic structure and Fermi surface of untwinned CaFe2As2: Obtaining the electronic structure of the newly discovered iron-based superconductors is the key to understanding the mechanism of their high-temperature superconductivity. We used angle-resolved photoemission spectroscopy (ARPES) t...
cond-mat_supr-con
Theory of the superconductivity of $UGe_2$ revisited: We present a unified theory of magnetism and superconductivity of $UGe_2$. To this end, we consider part of $5f$ uranium electrons as mostly itinerant and other ones as mostly localized. The main feature that distinguishes the localized from the itinerant electrons ...
cond-mat_supr-con
Fractal superconductivity near localization threshold: We develop a semi-quantitative theory of electron pairing and resulting superconductivity in bulk "poor conductors" in which Fermi energy $E_F$ is located in the region of localized states not so far from the Anderson mobility edge $E_c$. We review the existing the...
cond-mat_supr-con
Structural phase transition and superlattice misfit strain of RFeAsO (R = La, Pr, Nd and Sm): The tetragonal-to-orthorhombic structural phase transition (SPT) in LaFeAsO (La-1111) and SmFeAsO (Sm-1111) single crystals measured by high resolution x-ray diffraction is found to be sharp while the RFeAsO (R=La, Nd, Pr, S...
cond-mat_supr-con
Quantum mechanics of superconducting nanowires: In a short superconducting nanowire connected to bulk superconducting leads, quantum phase slips behave as a system of linearly (as opposed to logarithmically) interacting charges. This system maps onto quantum mechanics of a particle in a periodic potential. We show that...
cond-mat_supr-con
Nematic state stabilized by off-site Coulomb interaction in iron-based superconductors: Using a variational Monte Carlo method, we investigate the nematic state in iron-base superconductors based on a three-band Hubbard model. Our results demonstrate that the nematic state, formed by introducing an anisotropic hoppin...
cond-mat_supr-con
Transition Temperature and Upper Critical Field in SmFeAsO1-xFx Synthesized at Low Heating Temperatures: Low-temperature synthesis is a promising and potentially effective method for improving superconducting properties. We report on the fabrication of polycrystalline samples of SmFeAsO1-xFx with nominal x content va...
cond-mat_supr-con