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Generalized boundary conditions for the circuit theory of mesoscopic transport: The circuit theory of mesoscopic transport provides a unified framework to describe spin-dependent or superconductivity-related phenomena. We extend this theory to hybrid systems of normal metals, ferromagnets and superconductors. Our mai...
cond-mat_supr-con
On the roles of graphene oxide doping for enhanced supercurrent in MgB2 based superconductors: Due to their graphene-like properties after oxygen reduction, incorporation of graphene oxide (GO) sheets into correlated-electron materials offers a new pathway for tailoring their properties. Fabricating GO nanocomposites...
cond-mat_supr-con
The underdoped-overdoped transition in YBa_2Cu_3O_x: Oxygen doping in metallic YBa_2Cu_3O_x induces quadrupolar "alpha-ortho'', and breathing "beta-ortho" deformations of the CuO_2 planes. Breathing beta-ortho deformations favour hybridizations of the pd sigma Cu3d_x^2-y^2 - O2p_x,y with the pd pi Cu3d_x,z, 3d_y,z-O2p_...
cond-mat_supr-con
Magnetization Measurement of a Possible High-Temperature Superconducting State in Amorphous Carbon Doped with Sulfur: Magnetization M(T,H) measurements performed on thoroughly characterized commercial amorphous carbon powder doped with sulfur (AC-S), revealed the occurrence of an inhomogeneous superconductivity (SC) ...
cond-mat_supr-con
Coexistence of orbital degeneracy lifting and superconductivity in iron-based superconductors: In contrast to conventional superconducting (SC) materials, superconductivity in high-temperature superconductors (HTCs) usually emerges in the presence of other fluctuating orders with similar or higher energy scales, thus...
cond-mat_supr-con
Nonlatching Superconducting Nanowire Single-Photon Detection with Quasi-Constant-Voltage Bias: Latching is a serious issue in superconducting nanowire single-photon detector (SNSPD) technology. By extensively studying the electrical transportation characteristics of SNSPD with different bias schemes, we conclude that...
cond-mat_supr-con
Anomalous Fano factor as a signature of Bogoliubov Fermi surfaces: Noise spectroscopy is a key technique to investigate the nature and dynamics of charge carriers in superconductors. The recently discovered superconducting hybrids with Bogoliubov Fermi surfaces exhibit a particularly intriguing and rich charge dynamics...
cond-mat_supr-con
Josephson junctions of topological nodal superconductors: Transition metal dichalcogenides (TMDs) offer a unique platform to study unconventional superconductivity, owing to the presence of strong spin-orbit coupling and a remarkable stability to an in-plane magnetic field. A recent study found that when an in-plane fi...
cond-mat_supr-con
High-temperature surface superconductivity in rhombohedral graphite: Surface superconductivity in rhombohedral graphite is a robust phenomenon which can exist even when higher order hoppings between the layers lift the topological protection of the surface flat band and introduce a quadratic dispersion of electrons wit...
cond-mat_supr-con
Competing Superconducting States in Strong Ferromagnets: We report results from a systematic study of the competition of exotic triplet pair density wave (PDW) superconductivity (SC) with homogeneous (zero pair momentum) SC in strongly polarized media such as half metallic systems. From the two different PDW states all...
cond-mat_supr-con
Thermodynamic signatures of quantum criticality in cuprates: The three central phenomena of cuprate superconductors are linked by a common doping $p^{\star}$, where the enigmatic pseudogap phase ends, around which the superconducting phase forms a dome, and at which the resistivity exhibits an anomalous linear dependen...
cond-mat_supr-con
Theory of thermally activated vortex bundles flow over the directional-dependent potential barriers in type-II superocnductors: The thermally activated vortex bundle flow over the directional-dependent energy barrier in type-II superconductors is investigated. The coherent oscillation frequency and the mean direction...
cond-mat_supr-con
Bound states and impurity averaging in unconventional superconductors: The question of anomalous transport due to a band of impurity states in unconventional superconductors is discussed. In general, the bound state energies are not in midgap, even in the unitarity limit. This implies that, generically, the states asso...
cond-mat_supr-con
Existence of the Abrikosov vortex state in two-dimensional type-II superconductors without pinning: Theory alternative to the vortex lattice melting theories is advertised. The vortex lattice melting theories are science fiction cond-mat/9811051 because the Abrikosov state is not the vortex lattice with crystalline l...
cond-mat_supr-con
Suppression of Tunneling of Superconducting Vortices Caused by a Remote Gate: Example of an Extended Object Tunneling: We discuss a recent experiment in which the resistance of a superconducting film has been measured in magnetic field. A strong decrease of the superconducting film resistance has been observed when a...
cond-mat_supr-con
Role of Sb in the superconducting kagome metal CsV$_3$Sb$_5$ revealed by its anisotropic compression: Pressure evolution of the superconducting kagome metal CsV$_3$Sb$_5$ is studied with single-crystal x-ray diffraction and density-functional band-structure calculations. A highly anisotropic compression observed up t...
cond-mat_supr-con
Energy dependence of a vortex line length near a zigzag of pinning centers: A vortex line, shaped by a zigzag of pinning centers, is described here through a three-dimensional unit cell containing two pinning centers positioned symmetrically with respect to its center. The unit cell is a cube of side $L=12\xi$, the p...
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Searching for Superconductivity in High Entropy Oxide Ruddlesden-Popper Cuprate Films: In this work, the high entropy oxide A2CuO4 Ruddlesden-Popper (La0.2Pr0.2Nd0.2Sm0.2Eu0.2)2CuO4 is explored by charge doping with Ce+4 and Sr+2 at concentrations known to induce superconductivity in the simple parent compounds, Nd2C...
cond-mat_supr-con
Tunneling spectroscopy for ferromagnet/superconductor junctions: In tunneling spectroscopy studies of ferromagnet/superconductor (F/S) junctions, the effects of spin polarization, Fermi wavevector mismatch (FWM) between the F and S regions, and interfacial resistance play a crucial role. We study the low bias conductan...
cond-mat_supr-con
Suppression of surface barrier in superconductors by columnar defects: We investigate the influence of columnar defects in layered superconductors on the thermally activated penetration of pancake vortices through the surface barrier. Columnar defects, located near the surface, facilitate penetration of vortices throug...
cond-mat_supr-con
Detection of Geometric Phases in Flux Qubits with Coherent Pulses: We propose a experimentally feasible scheme to demonstrate the geometric phase in flux qubits by means of detuning coherent microwave pulse techniques. Through measuring the probability of the persistent current state in flux qubits, one can detect the ...
cond-mat_supr-con
Probing the Order Parameter of Superconducting LiFeAs using Pb/LiFeAs and Au/LiFeAs Point-Contact Spectroscopy: We have fabricated c-axis point contact junctions between high-quality LiFeAs single crystals and Pb or Au tips in order to study the nature of the superconducting order parameter of LiFeAs, one of the few ...
cond-mat_supr-con
Josephson current through a long quantum wire: The dc Josephson current through a long SNS junction receives contributions from both Andreev bound states localized in the normal region as well as from scattering states incoming from the superconducting leads. We show that in the limit of a long junction, this current, ...
cond-mat_supr-con
Electronic structure of new quaternary superconductors LaONiBi and LaOCuBi from first principles: Based on first-principles FLAPW-GGA calculations, we have investigated the electronic structure of newly synthesized novel superconductors LaONiBi and LaOCuBi, the first bismuth-containing compounds from the family of qu...
cond-mat_supr-con
Josephson critical currents in annular superconductors with Pearl vortices: We investigate the influence of Pearl vortices in the vicinity of an edge-type Josephson junction for a superconducting thin-film loop in the form of an annulus, under uniform magnetic field. Specifically, we obtain the exact analytic formula...
cond-mat_supr-con
Band-selective clean- and dirty-limit superconductivity with nodeless gaps in the bilayer iron-based superconductor CsCa$_2$Fe$_4$As$_4$F$_2$: The optical properties of the new iron-based superconductor CsCa$_2$Fe$_4$As$_4$F$_2$ with $T_c \sim 29$~K have been determined. In the normal state a good description of the ...
cond-mat_supr-con
Evidence from $^{77}$Se Knight shifts for triplet superconductivity in (TMTSF)$_2$PF$_6$: The layered quasi-one-dimensional molecular superconductor (TMTSF)$_2$PF$_6$ is a very exotic material with a superconducting order parameter whose ground state symmetry has remained ill-defined. Here we present a pulsed NMR Kni...
cond-mat_supr-con
Complete zero-energy flat bands of surface states in fully gapped chiral noncentrosymmetric superconductors: Noncentrosymmetric superconductors can support flat bands of zero-energy surface states in part of their surface Brillouin zone. This requires that they obey time-reversal symmetry and have a sufficiently stro...
cond-mat_supr-con
Superconductivity in novel BiS2-based layered superconductor LaO1-xFxBiS2: Layered superconductors have provided some interesting fields in condensed matter physics owing to the low dimensionality of their electronic states. For example, the high-Tc (high transition temperature) cuprates and the Fe-based superconduct...
cond-mat_supr-con
Advanced surface characterization of Ba(Fe$_{0.92}$Co$_{0.08}$)$_2$As$_2$ epitaxial thin films: We report on the systematic characterization of Ba(Fe$_{0.92}$Co$_{0.08}$)$_2$As$_2$ epitaxial thin films on CaF$_2$ substrate in view of their possible use for superconducting electronic applications. By using different a...
cond-mat_supr-con
Superconductivity and abnormal pressure effect in Sr0.5La0.5FBiSe2 superconductor: Through the solid state reaction method, we synthesized a new BiSe2-based superconductor Sr0:5La0:5FBiSe2 with superconducting transition temperature Tc?3.8 K. A strong diamagnetic signal below Tc in susceptibility ?(T) is observed ind...
cond-mat_supr-con
Majorana spintronics: We propose a systematic magnetic-flux-free approach to detect, manipulate and braid Majorana fermions in a semiconductor nanowire-based topological Josephson junction by utilizing the Majorana spin degree of freedom. We find an intrinsic $\pi$-phase difference between spin-triplet pairings enforce...
cond-mat_supr-con
Magnetism in SQUIDs at Millikelvin Temperatures: We have characterized the temperature dependence of the flux threading dc SQUIDs cooled to millikelvin temperatures. The flux increases as 1/T as temperature is lowered; moreover, the flux change is proportional to the density of trapped vortices. The data is compatible ...
cond-mat_supr-con
In-situ fabrication of cobalt-doped SrFe2As2 thin films by using pulsed laser deposition with excimer laser: The remarkably high superconducting transition temperature and upper critical field of iron(Fe)-based layered superconductors, despite ferromagnetic material base, open the prospect for superconducting electro...
cond-mat_supr-con
Quantum Phase Transitions in Superconducting Arrays with General Capacitance Matrices: We investigate quantum phase transitions in two-dimensional superconducting arrays with general capacitance matrices and discrete charge states. We use the perturbation theory together with the simulated annealing method to obtain ...
cond-mat_supr-con
Quasiparticle entropy in superconductor/normal metal/superconductor proximity junctions in the diffusive limit: We discuss the quasiparticle entropy and heat capacity of a dirty superconductor-normal metal-superconductor junction. In the case of short junctions, the inverse proximity effect extending in the supercond...
cond-mat_supr-con
Amplitude `Higgs' mode in 2H-NbSe2 Superconductor: We report experimental evidences for the observation of the superconducting amplitude mode, so-called `Higgs' mode in the charge density wave superconductor 2H-NbSe2 using Raman scattering. By comparing 2H-NbSe2 and its iso-structural partner 2H-NbS2 which shows superc...
cond-mat_supr-con
Colossal thermomagnetic response in the exotic superconductor URu2Si2: When a superconductor is heated above its critical temperature $T_c$, macroscopic coherence vanishes, leaving behind droplets of thermally fluctuating Cooper pair. This superconducting fluctuation effect above $T_c$ has been investigated for many de...
cond-mat_supr-con
Characterizing two-dimensional superconductivity via nanoscale noise magnetometry with single-spin qubits: We propose nanoscale magnetometry via isolated single-spin qubits as a probe of superconductivity in two-dimensional materials. We characterize the magnetic field noise at the qubit location, arising from curren...
cond-mat_supr-con
Common Electronic Origin of Superconductivity in (Li,Fe)OHFeSe Bulk Superconductor and Single-Layer FeSe/SrTiO3 Films: The mechanism of high temperature superconductivity in the iron-based superconductors remains an outstanding issue in condensed matter physics. The electronic structure, in particular the Fermi surfa...
cond-mat_supr-con
Multiband superconductivity and a deep gap minimum from the specific heat in KCa$_2$(Fe$_{1-x}$Ni$_x$)$_4$As$_4$F$_2$ ($x$ = 0, 0.05, 0.13): Specific heat can explore low-energy quasiparticle excitations of superconductors, so it is a powerful tool for bulk measurement on the superconducting gap structure and pairing...
cond-mat_supr-con
Strain-driven nematicity of the odd-parity superconductivity in Sr$_x$Bi$_2$Se$_3$: We present a novel experimental evidence for the odd-parity nematic superconductivity in high-quality single crystals of doped topological insulator Sr$_x$Bi$_2$Se$_3$. The X-ray diffraction shows that the grown single crystals are ei...
cond-mat_supr-con
Chiral and helical $p$-wave superconductivity in doped bilayer BiH: We investigate the superconductivity (SC) driven by correlation effects in electron-doped bilayer BiH near a type-II van Hove singularity (vHS). By functional renormalization group, we find triplet $p$-wave pairing prevails in the interaction parameter...
cond-mat_supr-con
Instability of Majorana states in Shiba chains due to leakage into a topological substrate: We revisit the problem of Majorana states in chains of scalar impurities deposited on a superconductor with a mixed s-wave and p-wave pairing. We also study the formation of Majorana states for magnetic impurity chains. We fin...
cond-mat_supr-con
Mixed higher-order topology and nodal and nodeless flat band topological phases in a superconducting multiorbital model: We investigate the topological phases that appear in an orbital version of the Benalcazar-Bernevig-Hughes (BBH) model in the presence of conventional spin-singlet $s$-wave superconductivity and wit...
cond-mat_supr-con
Spin Transport in Half-Metallic Ferromagnet-Superconductor Junctions: We investigate the charge and spin transport in half-metallic ferromagnet ($F$) and superconductor ($S$) nanojunctions. We utilize a self-consistent microscopic method that can accommodate the broad range of energy scales present, and ensures proximi...
cond-mat_supr-con
Hall coefficient and angle-resolved photoemission in systems with strong pair fluctuations: We examine the normal-state temperature and doping dependence of the Hall coefficient in the context of a pair-fluctuation scenario, based on a model where itinerant electrons are hybridized with localized electron pairs via a...
cond-mat_supr-con
From Cooper-pair glass to unconventional superconductivity: a unified approach to cuprates and pnictides: We report a microscopic model wherein the unconventional superconductivity emerges from an incoherent `Cooper-pair glass' state. Driven by the pair-pair interaction, a new type of quasi-Bose phase transition is a...
cond-mat_supr-con
Resilience of d-wave superconductivity to nearest-neighbor repulsion: Many theoretical approaches find d-wave superconductivity in the prototypical one-band Hubbard model for high-temperature superconductors. At strong-coupling (U > W, where U is the on-site repulsion and W=8t the bandwidth) pairing is controlled by th...
cond-mat_supr-con
Key Ingredients for Superconductivity in Cuprates: Using high resolution angle-resolved photoemission data in conjunction with that from neutron and other probes, we show that electron-phonon (el-ph) coupling is strong in cuprates superconductors and it plays an important role in pairing. In addition to the strong elec...
cond-mat_supr-con
Interplay between magnetism and superconductivity in EuFe(2-x)Co(x)As2 studied by 57Fe and 151Eu Mössbauer spectroscopy: The compound EuFe(2-x)Co(x)As2 was investigated by means of the 57Fe and 151Eu Moessbauer spectroscopy versus temperature (4.2 - 300 K) for x=0 (parent), x=0.34 - 0.39 (superconductor) and x=0.58 (...
cond-mat_supr-con
Resistive transition in disordered superconductors with varying intergrain coupling: The effect of disorder is investigated in granular superconductive materials with strong and weak links. The transition is controlled by the interplay of the \emph{tunneling} $g$ and \emph{intragrain} $g_{intr}$ conductances, which d...
cond-mat_supr-con
Superconductivity of cerium under pressures up to 54GPa: Cerium is a fascinating element due to its diverse physical properties, which include forming various crystal structures ($\gamma$, $\alpha$, $\alpha^{'}$, $\alpha^{''}$ and $\epsilon$), mixed valence behavior and superconductivity, making it an ideal platform fo...
cond-mat_supr-con
Surface states and local spin susceptibility in doped three-dimensional topological insulators with odd-parity superconducting pairing symmetry: We investigate characteristic features in the spin response of doped three-dimensional topological insulators with odd-parity unequal-spin superconducting pairing, which are...
cond-mat_supr-con
Charge distribution in C$_{60}$ crystal doped by electric field: The calculations of the charge distribution in C$_{60}$-based FET structure are presented. A simple model is proposed to describe the distribution of the injected electrons or holes between two-dimensional layers. The calculations show that the relative c...
cond-mat_supr-con
Half-integer Shapiro-steps in superconducting qubit with a $π$-Josephson junction: A superconducting quantum interference device (SQUID) comprising 0- and $\pi$-Josephson junctions (JJs), called $\pi$-SQUID, is studied by the resistively shunted junction model. The $\pi$-SQUID shows half-integer Shapiro-steps (SS) un...
cond-mat_supr-con
Controlling Factors of Tc-Dome Structure in 1111-Type Iron Arsenide Superconductors: We investigated the effects of phosphorus substitution on the shape of the Tc(x) dome in 1111-type SmFeAs1-yPyO1-xHx (0 < x < 0.5). Hydride ion substitution of oxide sites (O2- -> H-) exerts a chemical pressure effect, i.e., a struct...
cond-mat_supr-con
Properties of a two orbital model for oxypnictide superconductors: Magnetic order, B_2g spin-singlet pairing channel, and its nodal structure: A two orbital model for the new Fe-based superconductors is studied using the Lanczos method as well as pairing mean-field approximations. Our main goals are (i) to provide a ...
cond-mat_supr-con
Doping dependent optical properties of Bi2201: An experimental study of the in-plane optical conductivity of (Pb$_{x}$,Bi$_{2-x}$)(La$_{y}$Sr$_{2-y}$)CuO$_{6+\delta}$ (Bi2201) is presented for a broad doping and temperature range. The in-plane conductivity is analyzed within a strong coupling formalism. We address the ...
cond-mat_supr-con
Proximity of LaOFeAs to a magnetic instability: We investigate the effect of external pressure on the Fe magnetic moment in undoped LaOFeAs within the framework of density functional theory and show that this system is close to a magnetic instability: The Fe moment is found to drop by nearly a factor of 3 within a pres...
cond-mat_supr-con
Local characterization of superconductivity in BaFe2(As1-xPx)2: We use magnetic force microscopy (MFM) to characterize superconductivity across the superconducting dome in ${\rm {BaFe}_2 \left(As_{1-x}P_x\right)_2}$, a pnictide with a peak in the penetration depth ($\lambda_{ab}$) at optimal doping ($\rm x_{opt}$), as ...
cond-mat_supr-con
Controlling spin supercurrents via nonequilibrium spin injection: We propose a mechanism whereby spin supercurrents can be manipulated in superconductor/ferromagnet proximity systems via nonequilibrium spin injection. We find that if a spin supercurrent exists in equilibrium, a nonequilibrium spin accumulation will exe...
cond-mat_supr-con
Condensate entanglement and multigap superconductivity in nanoscale superconductors: A Green functions approach is used to study superconductivity in nanofilms and nanowires. We show that the superconducting condensate results from the multimodal entanglement, or internal Josephson coupling, of the subcondensates ass...
cond-mat_supr-con
Determining Pair Interactions from Structural Correlations: We examine metastable configurations of a two-dimensional system of interacting particles on a quenched random potential landscape and ask how the configurational pair correlation function is related to the particle interactions and the statistical properties ...
cond-mat_supr-con
Andreev bound states in rounded corners of d-wave superconductors: Andreev bound states at boundaries of d-wave superconductors are strongly influenced by the boundary geometry itself. In this work, the zero-energy spectral weight of the local quasiparticle density of states is presented for the case of wedge-shaped bo...
cond-mat_supr-con
Magnetic properties of magnetically textured Bi-2212 ceramics: This paper aims at reporting magnetic properties of bulk polycrystalline Bi2Sr2Ca0.8Dy0.2Cu2O8-y samples textured under a magnetic field. The microstructure of these materials is highly anisotropic and exhibits particular features needed to be taken into ac...
cond-mat_supr-con
Anisotropy of the upper critical fields and the paramagnetic Meissner effect in La1.85Sr0.15CuO4 single Crystals: Optimally-doped La1.85Sr0.15CuO4 single crystals have been investigated by dc and ac magnetic measurements. These crystals have rectangular needle-like shapes with the long needle axis parallel to the cry...
cond-mat_supr-con
Metastability in Josephson transmission lines: Thermal activation and macroscopic quantum tunneling in current-biased discrete Josephson transmission lines are studied theoretically. The degrees of freedom under consideration are the phases across the junctions which are coupled to each other via the inductances of the...
cond-mat_supr-con
Deterministic Josephson Vortex Ratchet with a load: We investigate experimentally a deterministic underdamped Josephson vortex ratchet -- a fluxon-particle moving along a Josephson junction in an asymmetric periodic potential. By applying a sinusoidal driving current one can compel the vortex to move in a certain direc...
cond-mat_supr-con
Tunable two-dimensional superconductivity and spin-orbit coupling at the EuO/KTaO3(110) interface: Unconventional quantum states, most notably the two-dimensional (2D) superconductivity, have been realized at the interfaces of oxide heterostructures where they can be effectively tuned by the gate voltage ($V_G$). Her...
cond-mat_supr-con
Superconducting energy gap and c-axis plasma frequency of (Nd,Sm)O0.82F0.18FeAs superconductors from infrared ellipsometry: We present ellipsometric measurements of the far-infrared dielectric response of polycrystalline samples of the new pnictide superconductor RO0.82F0.18FeAs (R=Nd and Sm). We find evidence that t...
cond-mat_supr-con
Scaling of the Fano effect of the in-plane Fe-As phonon and the superconducting critical temperature in Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$: By means of infrared spectroscopy we determine the temperature-doping phase diagram of the Fano effect for the in-plane Fe-As stretching mode in Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$....
cond-mat_supr-con
Ab initio Study of Cross-Interface Electron-Phonon Couplings in FeSe Thin Films on SrTiO$_3$ and BaTiO$_3$: We study the electron-phonon coupling strength near the interface of monolayer and bilayer FeSe thin films on SrTiO$_3$, BaTiO$_3$, and oxygen-vacant SrTiO$_3$ substrates, using ab initio methods. The calculate...
cond-mat_supr-con
High-Density Superconductive Logic Circuits Utilizing 0 and $π$ Josephson Junctions: Superconductor Electronics (SCE) is a fast and power-efficient technology with great potential for overcoming conventional CMOS electronics' scaling limits. Nevertheless, the primary challenge confronting SCE today pertains to its in...
cond-mat_supr-con
Z$_2$ topology and superconductivity from symmetry lowering of a 3D Dirac Metal Au$_2$Pb: 3D Dirac semi-metals (DSMs) are materials that have massless Dirac electrons and exhibit exotic physical properties It has been suggested that structurally distorting a DSM can create a Topological Insulator (TI), but this has n...
cond-mat_supr-con
Generation of Teraherz Oscillations by Thin Superconducting Film in Fluctuation Regime: Explicit analytical expressions for conductivity of a superconducting film above and below critical temperature in an arbitrary electric field are derived in the frameworks of the time dependent Ginzburg-Landau theory. It is confi...
cond-mat_supr-con
High Tc superconductivity in heavy Rare Earth Hydrides: correlation between the presence of the f states on the Fermi surface, nesting and the value of Tc: Lanthanum hydrides, containing hydrogen framework structures under compression, display a superconducting state with a high observed critical temperature. Howev...
cond-mat_supr-con
Superconductivity at 15.6 K in Calcium-doped Tb_{1-x}Ca_xFeAsO: the structure requirement for achieving superconductivity in the hole-doped 1111 phase: Superconductivity at about 15.6 K was achieved in Tb_{1-x}Ca_xFeAsO by partially substituting Tb^{3+} with Ca^{2+} in the nominal doping region x = 0.40 \sim 0.50. ...
cond-mat_supr-con
Robust nodal superconductivity induced by isovalent doping in Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ and BaFe$_2$(As$_{1-x}$P$_x$)$_2$: We present the ultra-low-temperature heat transport study of iron-based superconductors Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ and BaFe$_2$(As$_{1-x}$P$_x$)$_2$. For optimally doped Ba(Fe$_{0.64}$Ru...
cond-mat_supr-con
How to measure the spatial correlations in disordered Berezinski-Kosterlitz-Thouless transition ?: The Berezinski-Kosterlitz-Thouless transition is a unique two dimensional phase transition, separating two phases with exponentially and power-law decaying correlations, respectively. In disordered systems, these correl...
cond-mat_supr-con
Percolative nature of the dc paraconductivity in the cuprate superconductors: We present an investigation of the planar direct-current (dc) paraconductivity of the model cuprate material HgBa$_2$CuO$_{4+\delta}$ in the underdoped part of the phase diagram. The simple quadratic temperature-dependence of the Fermi-liqu...
cond-mat_supr-con
Double-helix magnetic order in CrAs with Pnma space group: The transition metal pnictide CrAs exhibits superconductivity in the vicinity of a helimagnetic phase, where it has been found that the propagation vector is parallel to the c axis and the magnetic moments lie in the ab plane. Here we use ab initio calculations...
cond-mat_supr-con
Unusual Hole-doping-dependent Electronic Instability and Electron-Phonon Coupling in Infinite-layer Nickelates: The interplay between superconductivity and charge density waves (CDWs) under hole doping in cuprates is one of the central phenomena in condensed matter physics. Recently, CDWs are also observed in CaCuO$_...
cond-mat_supr-con
Optical conductivity of iron-based superconductors: The new family of unconventional iron-based superconductors discovered in 2006 immediately relieved their copper-based high-temperature predecessors as the most actively studied superconducting compounds in the world. The experimental and theoretical effort made in or...
cond-mat_supr-con
Paramagnon dispersion and damping in doped Na$_{x}$Ca$_{2-x}$CuO$_2$Cl$_2$: Using Resonant Inelastic X-ray Scattering, we measure the paramagnon dispersion and damping of undoped, antiferromagnetic Ca$_2$CuO$_2$Cl$_2$ as well as doped, superconducting Na$_{x}$Ca$_{2-x}$CuO$_2$Cl$_2$. Our estimation of the spin-exchan...
cond-mat_supr-con
Shell Structure and Strengthening of Superconducting Pair Correlation in Nanoclusters: The existence of shell structure and the accompanying high degeneracy of electronic levels leads to the possibility of strong superconducting pairing in metallic nanoclusters with N~100-1000 delocalized electrons. The most favorabl...
cond-mat_supr-con
Hidden magnetic excitation in the pseudogap phase of a model cuprate superconductor: The elucidation of the pseudogap phenomenon of the cuprates, a set of anomalous physical properties below the characteristic temperature T* and above the superconducting transition temperature Tc, has been a major challenge in conden...
cond-mat_supr-con
Microwave Surface Impedance Measurements of the Electronic State and Dissipation of Magnetic Vortices in Superconducting Iron-Based LiFeAs Single Crystals: LiFeAs is one of the iron-based superconductors having multiple gaps with the possible sign reversal. To clarify how those novel natures affect the energy dissi...
cond-mat_supr-con
Superconductivity at 17 K in (Fe2P2)(Sr4Sc2O6): a new superconducting layered pnictide oxide with a thick perovskite oxide layer: A new layered oxypnictide (Fe2P2)(Sr4Sc2O6) have been synthesized by solid-state reaction. This material has an alternating layer stacking structure of anti-fluorite Fe2P2 and perovskite-b...
cond-mat_supr-con
Direct observation of melting in a 2-D superconducting vortex lattice: Topological defects such as dislocations and disclinations are predicted to determine the twodimensional (2-D) melting transition. In 2-D superconducting vortex lattices, macroscopic measurements evidence melting close to the transition to the norma...
cond-mat_supr-con
New Series of Nickel-Based Pnictide Oxide Superconductors (Ni2Pn2)(Sr4Sc2O6) (Pn = P, As): We have discovered new nickel-based pnictide oxide superconductors, (Ni2Pn2)(Sr4Sc2O6) (Pn = P, As). These compounds have a tetragonal unit cell with a space group of P4/nmm and they consist of alternate stacking of anti-fluori...
cond-mat_supr-con
Pressure-Induced Superconductivity and Its Scaling with Doping-Induced Superconductivity in the Iron Pnictide with Skutterudite Intermediary Layers: The Ca10(PtnAs8)(Fe2As2)5 (n=3,4) compounds are a new type of iron pnictide superconductors whose structures consist of stacking Ca-PtnAs8-Ca-Fe2As2 layers in a unit cel...
cond-mat_supr-con
Possible Dynamic States in Inductively Coupled Intrinsic Josephson Junctions of Layered High-$T_c$ Superconductors: Based on computer simulations and theoretical analysis, a new dynamic state is found in inductively coupled intrinsic Josephson junctions in the absence of an external magnetic field. In this state, the...
cond-mat_supr-con
Critical currents in superconductors with quasiperiodic pinning arrays: One-dimensional chains and two-dimensional Penrose lattices: We study the critical depinning current J_c, as a function of the applied magnetic flux Phi, for quasiperiodic (QP) pinning arrays, including one-dimensional (1D) chains and two-dimensi...
cond-mat_supr-con
Nonequilibrium transport via spin-induced sub-gap states in superconductor/quantum dot/normal metal cotunnel junctions: We study low-temperature transport through a Coulomb blockaded quantum dot (QD) contacted by a normal (N), and a superconducting (S) electrode. Within an effective cotunneling model the conduction e...
cond-mat_supr-con
Temperature and polarization dependence of low-energy magnetic fluctuations in nearly-optimal-doped NaFe$_{0.9785}$Co$_{0.0215}$As: We use unpolarized and polarized neutron scattering to study the temperature and polarization dependence of low-energy magnetic fluctuations in nearly-optimal-doped NaFe$_{0.9785}$Co$_{0...
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Elementary vortex pinning potential in a chiral p-wave superconductor: The elementary vortex pinning potential is studied in a chiral p-wave superconductor with a pairing d=z(k_x + i k_y) on the basis of the quasiclassical theory of superconductivity. An analytical investigation and numerical results are presented to s...
cond-mat_supr-con
The geometric theory of low dimensional superconductivity: The study of the electromagnetic properties of 2D materials is an area of intensive research. Most of the efforts in the subject have been oriented towards the understanding and modelling of the microscopic behaviour of the charge carriers within the medium. Al...
cond-mat_supr-con
Further detailing of the Bose-Einstein negative-U state in the high temperature superconducting cuprates: The cause of the sharp and universal optimization of the HTSC condensation energy at the hole doping concentration of p = 0.19 is identified within the context of the boson-fermion negative-U modelling and stripe...
cond-mat_supr-con
Melting of the vortex lattice in high $T_{c}$ superconductors: The precise measurements of vortex melting point towards a need to develop a quantitative theoretical description of thermal fluctuations in vortex matter. To tackle the difficult problem of melting, the description of both the solid and the liquid phase sh...
cond-mat_supr-con