Latest in cond-mat.supr-con

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Orbital Origin of Extremely Anisotropic Superconducting Gap in Nematic Phase of FeSe SuperconductorFeb 08 2018The iron-based superconductors are characterized by multiple-orbital physics where all the five Fe 3$d$ orbitals get involved. The multiple-orbital nature gives rise to various novel phenomena like orbital-selective Mott transition, nematicity and orbital ... More
Optical single photon detection in micron-scaled NbN bridgesFeb 08 2018We demonstrate experimentally that single photon detection can be achieved in micron-wide NbN bridges, with widths ranging from 0.53 $\mu$m to 5.15 $\mu$m and for photon-wavelengths from 408 nm to 1550 nm. The microbridges are biased with a dc current ... More
Weak doping dependence of the antiferromagnetic coupling between nearest-neighbor Mn$^{2+}$ spins in (Ba$_{1-x}$K$_x$)(Zn$_{1-y}$Mn$_y$)$_2$As$_2$Feb 08 2018Dilute magnetic semiconductors (DMS) are nonmagnetic semiconductors doped with magnetic transition metals. The recently discovered DMS material (Ba$_{1-x}$K$_{x}$)(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$ offers a unique and versatile control of the Curie temperature, ... More
Electronic and optical properties of La-doped Sr$_3$Ir$_2$O$_7$ epitaxial thin-filmsFeb 08 2018We have investigated structural, transport, and optical properties of tensile strained (Sr$_{1-x}$La$_x$)$_3$Ir$_2$O$_7$ (x = 0, 0.025, 0.05) epitaxial thin-films. While High-T$_c$ superconductivity is predicted theoretically in the system, we have observed ... More
Direct observation of spin excitation anisotropy in the paramagnetic orthorhombic state of BaFe$_{2-x}$Ni$_x$As$_2$Feb 08 2018We use transport and inelastic neutron scattering measurements to investigate single crystals of iron pnictide BaFe$_{2-x}$Ni$_{x}$As$_{2}$ ($x=0,0.03$), which exhibit a tetragonal-to-orthorhombic structural transition at $T_s$ and stripe antiferromagnetic ... More
Superfluid density of a photo-induced superconducting stateFeb 07 2018Nonequilibrium conditions offer novel routes to superconductivity that are not available at equilibrium. For example, by engineering nonequilibrium electronic populations, pairing may develop between electrons in different energy bands. A concrete proposal ... More
From one-dimensional charge conserving superconductors to the gapless Haldane phaseFeb 07 2018We develop a framework to analyze one-dimensional topological superconductors with charge conservation. In particular, we consider models with $N$ flavors of fermions and $(\mathbb{Z}_2)^N$ symmetry, associated with the conservation of the fermionic parity ... More
High Pressure and Road to Room Temperature SuperconductivityFeb 07 2018High pressure serves as a path finding tool towards novel structures, including those with very high Tc.The superconductivity in sulfur hydrides with record value (203 K) is caused by the phonon mechanism. However, the picture differs from the conventional ... More
Loop currents from nonunitary chiral superconductivity on the honeycomb latticeFeb 07 2018We study a tight-binding model of chiral d-wave superconductivity on the honeycomb lattice. The nearest-neighbor pairing ensures a nontrivial sublattice structure and nonunitarity of the superconducting pairing potential. We show that it generates persistent ... More
Quantum Phase Transitions in Proximitized Josephson JunctionsFeb 07 2018We study fermion-parity-changing quantum phase transitions (QPTs) in platform Josephson junctions. These QPTs, associated with zero-energy bound states, are rather widely observed experimentally. They emerge from numerical calculations frequently without ... More
Pressure dependence of coherence-incoherence crossover behavior in KFe2As2 observed by resistivity and 75As-NMR/NQRFeb 07 2018We present the results of $^{75}$As nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), and resistivity measurements in KFe$_2$As$_2$ under pressure ($p$). The temperature dependence of the NMR shift, nuclear spin-lattice relaxation ... More
Via Method for Lithography Free Contact and Preservation of 2D MaterialsFeb 06 2018Atomically thin 2D materials span the common components of electronic circuits as metals, semi-conductors, and insulators, and can manifest correlated phases such as superconductivity, charge density waves, and magnetism. An ongoing challenge in the field ... More
Locating the missing superconducting electrons in overdoped cupratesFeb 06 2018Overdoped high-temperature cuprate superconductors have been widely believed to be described by the physics of d-wave BCS-like superconductivity. However, recent measurements indicate that as the doping is increased, the superfluid density decreases smoothly ... More
Nonlinear heat transport in ferromagnetic-quantum dot-superconducting systemsFeb 06 2018We analyze the heat current traversing a quantum dot sandwiched between a ferromagnetic and a superconducting electrode. The heat flow generated in response to a voltage bias presents rectification as a function of the gate potential applied to the quantum ... More
Odd and even modes of neutron spin resonance in the bilayer iron-based superconductor CaKFe$_4$As$_4$Feb 06 2018We report an inelastic neutron scattering study on the neutron spin resonance in the bilayer iron-based superconductor CaKFe$_4$As$_4$. We discover strongly $L-$dependent triple spin resonance modes below $T_c=35$ K. The modes can be classified into odd ... More
Circuit Quantum Electrodynamics of Granular Aluminum ResonatorsFeb 06 2018Feb 07 2018The introduction of crystalline defects or dopants can give rise to so-called "dirty superconductors", characterized by reduced coherence length and quasiparticle mean free path. In particular, granular superconductors such as Granular Aluminum (GrAl), ... More
Quasiparticle dynamics in granular aluminum close to the superconductor to insulator transitionFeb 06 2018Feb 07 2018Superconducting high kinetic inductance elements constitute a valuable resource for quantum circuit design and millimeter-wave detection. Granular aluminum (GrAl) in the superconducting regime is a particularly interesting material since it has already ... More
Pair Density Waves in Superconducting Vortex HalosFeb 05 2018We analyze the interplay between a d-wave uniform superconducting and a pair-density-wave (PDW) order parameter in the neighborhood of a vortex. We develop a phenomenological nonlinear sigma-model, solve the saddle point equation for the order parameter ... More
Time-reversal-symmetry breaking and unconventional pairing in the noncentrosymmetric superconductor La$_{7}$Rh$_{3}$ probed by $μ$SRFeb 05 2018Feb 06 2018Noncentrosymmetric superconductors are expected to exhibit many exciting properties, such as the admixture of spin-singlet and spin-triplet Cooper pairs. Unconventional pairing, however, has yet to be conclusively verified in any noncentrosymmetric superconductor ... More
Discrete superconducting phases in FeSe-derived superconductorsFeb 05 2018A general feature of unconventional superconductors is the existence of a superconducting dome in the phase diagram as a function of carrier concentration. For the simplest iron-based superconductor FeSe (with transition temperature Tc ~ 8 K), its Tc ... More
Two-dimensional Type-II Dirac Fermions in Layered OxidesFeb 05 2018Relativistic massless Dirac fermions can be probed with high-energy physics experiments, but appear also as low-energy quasi-particle excitations in electronic band structures. In condensed matter systems, their massless nature can be protected by crystal ... More
The interplay of phonon and exciton-mediated superconductivity in hybrid semiconductor-superconductor structuresFeb 05 2018We predict a strong enhancement of the critical temperature in a conventional Bardeen-Cooper-Schrieffer (BCS) superconductor in the presence of a bosonic condensate of exciton-polaritons. The effect depends strongly on the ratio of the cutoff frequencies ... More
Voltage-Controlled Superconducting Quantum BusFeb 05 2018We demonstrate the ability of an epitaxial semiconductor-superconductor nanowire to serve as a field-effect switch to tune a superconducting cavity. Two superconducting gatemon qubits are coupled to the cavity, which acts as a quantum bus. Using a gate ... More
Superconductivity in FeSe: the role of nematic orderFeb 03 2018Bulk FeSe is a special iron-based material in which superconductivity emerges inside a well-developed nematic phase. We present a microscopic model for this nematic superconducting state, which takes into account the mixing between $s-$wave and $d-$wave ... More
Integrable time-dependent Hamiltonians, solvable Landau-Zener models and Gaudin magnetsFeb 03 2018We solve the non-stationary Schrodinger equation for several time-dependent Hamiltonians, such as the BCS Hamiltonian with an interaction strength inversely proportional to time, periodically driven BCS and linearly driven inhomogeneous Dicke models as ... More
First-principles theory of magnetic multipoles in condensed matter systemsFeb 03 2018The multipole concept, which characterizes the spacial distribution of scalar and vector objects by their angular dependence, has already become widely used in various areas of physics. In recent years it has become employed to systematically classify ... More
Charge and current orders in the spin-fermion model with overlapping hot spotsFeb 02 2018Experiments carried over the last years on the underdoped cuprates have revealed a variety of symmetry-breaking phenomena in the pseudogap state. Charge-density waves, breaking of $C_{4}$ rotational symmetry as well as time-reversal symmetry breaking ... More
Evidence of a multiple boson emission in Sm$_{1-x}$Th$_x$OFeAsFeb 02 2018We studied a reproducible fine structure observed in dynamic conductance spectra of Andreev arrays in Sm$_{1-x}$Th$_x$OFeAs superconductors with various thorium concentrations ($x = 0.08 - 0.3$) and critical temperatures $T_c = 26-50$\,K. This structure ... More
Understanding the magnetism in noncentrosymmetric CeIrGe3: Muon spin relaxation and neutron scattering studiesFeb 01 2018The magnetic properties of a pressure induced noncentrosymmetric heavy-fermion superconductor CeIrGe$_3$ have been investigated by muon spin relaxation ($\mu$SR), powder neutron diffraction (ND) and inelastic neutron scattering (INS) techniques at ambient ... More
Spin-Imbalanced Pairing and Fermi Surface Deformation in Flat BandsFeb 01 2018We study the attractive Hubbard model with spin imbalance on two lattices featuring a flat band: the Lieb and kagome lattices. We present mean-field phase diagrams featuring exotic superfluid phases, similar to the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) ... More
Oxygen holes and hybridization in the bismuthatesJan 31 2018Motivated by the recently renewed interest in the superconducting bismuth perovskites, we investigate the electronic structure of the parent compounds ABiO$_{3}$ (A= Sr, Ba) using $ab$ $initio$ methods and tight-binding (TB) modeling. We use the density ... More
Exotic Superconductivity with Enhanced Energy Scales in Three Band Crossing MaterialsJan 31 2018Three band crossings can arise in three dimensional quantum materials with certain space group symmetries. The low energy Hamiltonian supports spin one fermions and a flat band. We study the pairing problem in this setting. We write down a minimal BCS ... More
Chain length effects of $p$-oligophenyls with comparison of benzene by Raman scatteringJan 31 2018Raman scattering measurements are performed on benzene and a number of $p$-oligophenyls including biphenyl, $p$-terphenyl, $p$-quaterphenyl, $p$-quinquephenyl, and $p$-sexiphenyl at ambient conditions. The vibrational modes of the intra- and intermolecular ... More
A Topological SQUIPT based on helical edge states in proximity to superconductorsJan 30 2018We propose a device based on a topological Josephson junction where the helical edge states of a two-dimensional topological insulator are in close proximity to two superconducting leads. The presence of a magnetic flux through the junction leads to a ... More
Nodal superconductivity coexists with low-moment static magnetism in single-crystalline tetragonal FeS: A muon spin relaxation and rotation studyJan 29 2018We report muon spin relaxation and rotation ($\mu$SR) measurements on hydrothermally-grown single crystals of the tetragonal superconductor~FeS, which help to clarify the controversial magnetic state and superconducting gap symmetry of this compound. ... More
Quantum metric contribution to the pair mass in spin-orbit coupled Fermi superfluidsJan 29 2018As a measure of the quantum distance between Bloch states in the Hilbert space, the quantum metric was introduced to solid-state physics through the real part of the so-called geometric Fubini-Study tensor, the imaginary part of which corresponds to the ... More
Revealing the intrinsic anisotropy of superconducting Sr$_x$Bi$_2$Se$_3$Jan 28 2018We reveal that unusual 2-fold in-plane symmetry of superconductivity, recently explored in Sr- doped topological insulator Bi$_2$Se$_3$, and associated with nematic topological superconductivity, is accompanied by co-aligned features in magnetoresistance ... More
Bogoliubov de Gennes equation on metric graphsJan 28 2018We consider Bogoliubov de Gennes equation on metric graphs. The vertex boundary conditions providing self-adjoint realization of the Bogoliubov de Gennes operator on a metric star graph are derived. Secular equation providing quantization of the energy ... More
Local Magnetic Measurements of Trapped Flux Through a Permanent Current Path in GraphiteJan 26 2018Temperature and field dependent measurements of the electrical resistance of different natural graphite samples, suggest the existence of superconductivity at room temperature in some regions of the samples. To verify whether dissipationless electrical ... More
FeSe films grown by DC sputtering from stoichiometric targets: thickness dependence of the physical propertiesJan 25 2018In this work, we study thickness effects in the structural and electronic properties of $\beta$-FeSe films grown by sputtering. We report a superconductor-insulator transition (SIT) as a function of thickness, for films in different substrates (SrTiO$_{3}$, ... More
Nernst effect in the electron-doped cuprate superconductor La2-xCexCuO4Jan 25 2018We report a systematic study of the Nernst effect in films of the electron doped cuprate superconductor La2-xCexCuO4 (LCCO) as a function of temperature and magnetic field (up to 14 T) over a range of doping from underdoped (x=0.08) to overdoped (x=0.16). ... More
Observation of Meissner effect in potassium-doped $p$-quaterphenylJan 24 2018Inspired by the discovery of high temperature superconductivity in potassium-doped $p$-terphenyl, we examine the possibility of superconductivity in $p$-quaterphenyl with one more phenyl ring than $p$-terphenyl. The Meissner effect with critical temperatures ... More
Superconductivity in the vicinity of a ferroelectric quantum phase transitionJan 24 2018Feb 06 2018Superconductivity has been observed in doped SrTiO$_3$ at charge-carrier densities below 10$^{18}$ cm$^{-3}$, where the density of states at the Fermi level of the itinerant electrons is several orders of magnitude lower than that of conventional metals. ... More
Peculiarities of phase dynamics of the Josephson junctions stack with the topologically nontrivial barriersJan 24 2018The peculiarities of the phase dynamics of stacks of coupled Josephson junctions with topologically trivial and nontrivial barriers have been investigated numerically and their comparative analysis is carried out. The effect of coupling and dissipation ... More
Interplay between superconductivity and magnetism in one-unit-cell LaAlO3 capped with SrTiO3Jan 24 2018To form a conducting layer at the interface between the oxide insulators LaAlO3 and SrTiO3, the LaAlO3 layer on the SrTiO3 substrate must be at least four unit-cells-thick. The LaAlO3 SrTiO3 heterointerface thus formed exhibits various intriguing phenomena ... More
Tailoring band-structure and band-filling in a simple cubic (IV, III) - VI superconductorJan 23 2018Jan 25 2018Superconductivity and its underlying mechanisms are one of the most active research fields in condensed-matter physics. An important question is how to enhance the transition temperature $T_{\rm c}$ of a superconductor. In this respect, the possibly positive ... More
Pressure induced BEC-BCS crossover in multi-band superconductorsJan 22 2018Superconductivity in strongly correlated systems is a remarkable phenomenon that attracts a huge interest. The study of this problem is relevant for materials as the high $T_c$ oxides, pnictides and heavy fermions. These systems also have in common the ... More
Transport evidence of Ising superconductivity in few-layer 1Td-MoTe2Jan 22 2018Unconventional superconductivity is one of the most fascinating and intriguing quantum phenomena in condensed matter physics. Recently, Ising superconductivity has been theoretically predicated and experimentally realized in noncentrosymmetric monolayer ... More
Unveiling the phase diagram of a striped cuprate at high magnetic fields: Hidden order of Cooper pairsJan 21 2018The interplay of charge orders with superconductivity in underdoped cuprates at high magnetic fields ($H$) is an open question, and even the value of the upper critical field ($H_{c2}$), a measure of the strength of superconductivity, has been the subject ... More
High pressure effects on non-fluorinated BiS2-based superconductors La$_{1-x}$M$_x$OBiS$_2$ (M = Ti and Th)Jan 19 2018Layered \textit{Ln}OBiS$_2$ compounds with \textit{Ln} = La, Ce, Pr, Nd, and Yb can be rendered conducting and superconducting via two routes, substitution of F for O or the tetravalent ions Ti, Zr, Hf, and Th for trivalent \textit{Ln} ions. Electrical ... More
Towards the issue of the nature of pseudogaps and Fermi arcs in cuprate HTSCsJan 19 2018Feb 02 2018Earlier we have proposed a new approach to the analysis of superconducting phase diagrams for cuprates and pnictides and have shown that the positions of superconducting domes on the diagrams can be predicted with high accuracy proceeding from only the ... More
Multimode cat codesJan 18 2018We introduce a driven-dissipative two-mode bosonic system whose reservoir causes simultaneous loss of two photons in each mode and whose steady states are superpositions of pair-coherent/Barut-Girardello coherent states. We show how quantum information ... More
Symmetry conditions of a nodal superconductor for generating robust flat-band Andreev bound states at its dirty surfaceJan 17 2018We discuss the symmetry property of a nodal superconductor that hosts robust flat-band zero-energy states at its surface under potential disorder. Such robust zero-energy states are known to induce the anomalous proximity effect in a dirty normal metal ... More
Cooper-pair size and binding energy for unconventional superconducting systemsJan 16 2018The main proposal of this paper is to analyze the size of the Cooper pairs composed by unbalanced mass fermions from different electronic bands along the BCS-BEC crossover and study the binding energy of the pairs. We are considering an interaction between ... More
Local Sensing with an AC Stark Spectrum AnalyzerJan 16 2018Analyzing weak microwave signals in the GHz regime is a challenging task if the signal level is very low and the photon energy widely undefined. Due to its discrete level structure, a superconducting qubit is only sensitive to photons of certain energies. ... More
Atomic-layer-resolved composition and electronic structure of the cuprate Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ from soft x-ray standing-wave photoemissionJan 16 2018A major remaining challenge in the superconducting cuprates is the unambiguous differentiation of the composition and electronic structure of the CuO$_2$ layers and those of the intermediate layers. The large c axis for these materials permits employing ... More
Electronic structure of the Mo$_{1-x}$Re$_x$ alloys studied through resonant photoemission spectroscopyJan 16 2018We have studied the electronic structure of Mo rich Mo$_{1-x}$Re$_x$ alloys (0$\leq$ x $\leq$0.4) using valence band photoemission spectroscopy in the photon energy range 23-70 eV and density of states calculations. Comparison of the photoemission spectra ... More
Study of the second magnetization peak and the pinning behaviour in Ba(Fe$_{0.935}$Co$_{0.065}$)$_2$As$_2Jan 16 2018Isothermal magnetic field dependence of magnetization and the magnetic relaxation measurements were performed for $H$$\parallel$c axis on single crystal of Ba(Fe$_{0.935}$Co$_{0.065}$)$_2$As$_2$ pnictide superconductor having $T_c$ = 21.7 K. The second ... More
Plastic pinning replaces collective pinning as the second magnetization peak disappears in the pnictide superconductor Ba-KFe$_2$As$_2$Jan 15 2018We report a detailed study of isofield magnetic relaxation and isothermal magnetization measurements with $H$$\parallel$c on an underdoped Ba$_{0.75}$K$_{0.25}$Fe$_2$As$_2$ pnictide single crystal, with superconducting transition temperature $T_c$ = 28 ... More
Magnetic and Superconducting Phase Diagram of Nb/Gd/Nb trilayersJan 15 2018Jan 17 2018We report on a study of the structural, magnetic and superconducting properties of Nb(25nm)/Gd($d_f$)/Nb(25nm) hybrid structures of a superconductor/ ferromagnet (S/F) type. The structural characterization of the samples, including careful determination ... More
Advanced first-principles theory of superconductivity including both lattice vibrations and spin fluctuations: The case of FeB$_4$Jan 13 2018We present an advanced method to study spin fluctuations in superconductors quantitatively, and entirely from first principles. This method can be generally applied to materials where electron-phonon coupling and spin fluctuations coexist. We employ it ... More
Common origin of the pseudogap in electron-doped and hole-doped cuprates governed by Mott physicsJan 12 2018The pseudogap phenomena have been a long-standing mystery of the cuprate high-temperature superconductors. Unlike the pseudogap in hole-doped cuprates, however, the pseudogap in the electron-doped counterpart has been attributed to band folding due to ... More
Spin-isotropic continuum of spin excitations in antiferromagnetically ordered Fe$_{1.07}$TeJan 11 2018Unconventional superconductivity typically emerges in the presence of quasi-degenerate ground states, and the associated intense fluctuations are likely responsible for generating the superconducting state. Here we use polarized neutron scattering to ... More
Microscopic investigation of the weakly correlated noncentrosymmetric superconductor SrAuSi$_3$Jan 11 2018SrAuSi$_3$ is a noncentrosymmetric superconductor (NCS) with $T_c$ = 1.54 K, which to date has been studied only via macroscopic techniques. By combining nuclear magnetic resonance (NMR) and muon-spin rotation ($\mu$SR) measurements we investigate both ... More
Influence of Magnetism and Correlation on the Spectral Properties of Doped Mott InsulatorsJan 11 2018Unravelling the nature of doping-induced transition between a Mott insulator and a weakly correlated metal is crucial to understanding novel emergent phases in strongly correlated materials. For this purpose, we study the evolution of spectral properties ... More
Metamaterial SuperconductorsJan 10 2018Searching for natural materials exhibiting larger electron-electron interactions constitutes a traditional approach to high temperature superconductivity research. Very recently we pointed out that the newly developed field of electromagnetic metamaterials ... More
The contribution of microwaves to the Cooper-pair condensate of a superconductor in the presence of inelastic processesJan 10 2018We analyse theoretically the influence of inelastic processes on coherent excited states of a superconductor generated by the application of microwaves. These states were identified recently [Phys. Rev. Lett. 117, 047002 (2016)] as the source of resonance ... More
Time Reversal Symmetry Breaking in noncentrosymmetric superconductor Re6TiJan 09 2018We have investigated the superconducting state of the noncentrosymmetric superconductor Re6Ti (Tc = 6.0 K) using muon-spin rotation/relaxation (muSR) technique. The zero-field muon experiment shows the presence of spontaneous magnetic fields in the superconducting ... More
The Chiral Non-Centrosymmetric Superconductors TaRh$_2$B$_2$ and NbRh$_2$B$_2$Jan 08 2018The symmetry of a material's crystal structure has a significant effect on the energy states of its electrons. Inversion symmetry, for example, results in energetically degenerate electron energy bands for electrons with wave vectors $\textit{k}$ and ... More
Superconductor Electronics Fabrication Process with MoN$_x$ Kinetic Inductors and Self-Shunted Josephson JunctionsJan 08 2018Recent progress in superconductor electronics fabrication has enabled single-flux-quantum (SFQ) digital circuits with close to one million Josephson junctions (JJs) on 1-cm$^2$ chips. Increasing the integration scale further is challenging because of ... More
Close proximity of FeSe to a magnetic quantum critical point as revealed by high-resolution $μ$SR measurementsJan 08 2018A nematic transition preceding a long-range spin density wave antiferromagnetic phase is a common feature of many Fe based superconductors. However, in the FeSe system with a nematic transition at $T_{\rm s} \approx$ 90 K no evidence for long-range static ... More
Quantum-enhanced magnetometry by phase estimation algorithms with a single artificial atomJan 07 2018Phase estimation algorithms are key protocols in quantum information processing. Besides applications in quantum computing, they can also be employed in metrology as they allow for fast extraction of information stored in the quantum state of a system. ... More
Geometry Effects on Switching Currents in Superconducting Ultra Thin FilmsDec 31 2017Vortex dynamics is strongly connected with the mechanisms responsible for the photon detection of superconducting devices. Indeed, the local suppression of superconductivity by photon absorption may trigger vortex nucleation and motion effects, which ... More
Absence of Local Fluctuating Dimers in Superconducting Ir$_{1-x}$(Pt,Rh)$_x$Te$_2$Dec 29 2017The compound IrTe2 is known to exhibit a transition to a modulated state featuring Ir-Ir dimers, with large associated atomic displacements. Partial substitution of Pt or Rh for Ir destabilizes the modulated structure and induces superconductivity. It ... More
Arrow of time and its reversal on IBM quantum computerDec 28 2017Uncovering the origin of the arrow of time remains a fundamental scientific challenge. Within the framework of statistical physics, this problem was inextricably associated with the Second Law of Thermodynamics, which declares that entropy growth proceeds ... More
Spin excitation spectrum of high-temperature cuprate superconductors from finite cluster simulationsDec 28 2017A cluster of spins $1/2$ of a finite size can be regarded as a basic building block of a spin texture in high-temperature cuprate superconductors. If this texture has the character of a network of weakly coupled spin clusters, then spin excitation spectra ... More
Theory of type-II superconductivity in ferromagnetic metals with triplet pairingDec 23 2017Jan 17 2018The superconducting state in uranium compounds UGe2, URhGe and UCoGe is formed at temperatures far below the Curie temperature pointing on nonconventional nature of superconductivity in these materials - namely the superconductivity with triplet pairing. ... More
Winding numbers of nodal points in Fe-based superconductorsDec 22 2017We analyze the nodal points in multi-orbital Fe-based superconductors from a topological perspective. We consider the $s^{+-}$ gap structure with accidental nodes, and the $d$-wave gap with nodes along the symmetry directions. In both cases, the nodal ... More
Observation of the 4$π$-periodic Josephson effect in InAs nanowiresDec 22 2017Quantum computation by non-Abelian Majorana zero modes (MZMs) offers an approach to achieve fault tolerance by encoding quantum information in the non-local charge parity states of semiconductor nanowire networks in the topological superconductor regime. ... More
Strain and ferroelectric soft mode induced superconductivity in strontium titanateDec 22 2017We investigate the effects of strain on superconductivity with particular reference to SrTiO$_3$. Assuming that a ferroelectric mode that softens under tensile strain is responsible for the coupling, an increase in the critical temperature and range of ... More
Electro-mechanical Casimir effectDec 21 2017The dynamical Casimir effect is an intriguing phenomenon in which photons are generated from vacuum due to a non-adiabatic change in some boundary conditions. In particular, it connects the motion of an accelerated mechanical mirror to the generation ... More
Higgs spectroscopy of superconductors in nonequilibriumDec 21 2017The collective non-equilibrium dynamics of superconducting condensates could not be studied systematically so far. The response in conventional optical pump-probe experiments contains almost no information on the actual ground state, since it is limited ... More
Revisiting $^{63}$Cu NMR evidence for charge order in superconducting La$_{1.885}$Sr$_{0.115}$CuO$_4$Dec 21 2017The presence of charge and spin stripe order in the La2CuO4-based family of superconductors continues to lead to new insight on the unusual ground state properties of high Tc cuprates. Soon after the discovery of charge stripe order at T(charge)=65K in ... More
Cu hyperfine coupling constants of HgBa$_{2}$Ca$_{}$Cu$_{2}$O$_{6+δ}$Dec 13 2017We estimated the ratios of $^{63}$Cu hyperfine coupling constants in the double-layer high-$T_\mathrm{c}$ superconductor HgBa$_2$CaCu$_2$O$_{6+\delta}$ from the anisotropies in Cu nuclear spin-lattice relaxation rates and spin Knight shifts to study the ... More
Pseudogap Behavior of the Nuclear Spin-lattice Relaxation Rate in FeSe Probed by $^{77}$Se-NMRDec 12 2017We conducted $^{77}$Se-nuclear magnetic resonance studies of the iron-based superconductor FeSe in magnetic fields of 0.6 to 19 T to investigate the superconducting and normal-state properties. The nuclear spin-lattice relaxation rate divided by the temperature ... More
Topology from TrivialityDec 06 2017We show that bringing into proximity two topologically trivial systems can give rise to a topological phase. More specifically, we study a 1D metallic nanowire proximitized by a 2D superconducting substrate with a mixed s-wave and p-wave pairing, and ... More
Andreev levels as a first approach to quantum computing with high Tc superconductorsDec 04 2017A computing platform based on low temperature superconductors (LTS) has already been proven both theoretically and experimentally. However, qubits based on high Tc superconductors (HTS) are not yet well understood. Here we study the Andreev bounds states ... More
Magnetic susceptibility of optimally doped HgBa$_{2}$CuO$_{4+δ}$Dec 02 2017The magnitude of the powder spin susceptibility of an optimally doped superconductor HgBa$_2$CuO$_{4+\delta}$ (Hg1201) in the normal state is found to be nearly the same as that of La$_{2-x}$Sr$_{x}$CuO$_{4}$ near the optimally doped level. The Stoner ... More
Nematicity, magnetism and superconductivity in FeSeNov 17 2017Iron-based superconductors are well known for their complex interplay between structure, magnetism and superconductivity. FeSe offers a particularly fascinating example. This material has been intensely discussed because of its extended nematic phase, ... More
Majorana Kramers pairs in Rashba double nanowires with interactions and disorderNov 13 2017Jan 25 2018We analyze the effects of electron-electron interactions and disorder on a Rashba double-nanowire setup coupled to an s-wave superconductor, which has been recently proposed as a versatile platform to generate Kramers pairs of Majorana bound states in ... More
Recent advances in iron-based superconductors toward applicationsOct 24 2017Iron with a large magnetic moment was widely believed to be harmful to the emergence of superconductivity because of the competition between the static ordering of electron spins and the dynamic formation of electron pairs (Cooper pairs). Thus, the discovery ... More
The three-dimensional electronic structure of the nematic and antiferromagnetic phases of NaFeAs from detwinned ARPES measurementsOct 10 2017We report a comprehensive ARPES study of NaFeAs, a prototypical parent compound of the Fe-based superconductors. By mechanically detwinning the samples, we show that in the nematic phase (below the structural transition at $T_s$ = 54 K but above the antiferromagnetic ... More
Direct visualization of phase separation between superconducting and nematic domains in Co-doped CaFe2As2 close to a first order phase transitionOct 05 2017We show that biaxial strain induces alternating tetragonal superconducting and orthorhombic nematic domains in Co substituted CaFe2As2. We use Atomic Force, Magnetic Force and Scanning Tunneling Microscopy (AFM, MFM and STM) to identify the domains and ... More
Two-Dimensional Holstein Model: Critical Temperature, Ising Universality, and Bipolaron LiquidSep 04 2017Sep 07 2017Fundamental open questions about the two-dimensional Holstein model of electrons coupled to quantum phonons are addressed by continuous-time quantum Monte Carlo simulations. The critical temperature of the charge-density-wave transition is determined ... More
Dynamic current susceptibility as a probe of Majorana bound states in nanowire-based Josephson junctionsAug 10 2017Aug 18 2017We theoretically study a Josephson junction based on a semiconducting nanowire subject to a time-dependent flux bias. We establish a general density matrix approach for the dynamical response of the Majorana junction and calculate the resulting flux-dependent ... More
Theory of the Josephson Junction LaserAug 08 2017We develop an analytic theory for the recently demonstrated Josephson Junction laser (Science 355, p. 939, 2017). By working in the time-domain representation (rather than the frequency-domain) a single non-linear equation is obtained for the dynamics ... More
Dynamic Elastoresistivity Evidence for Slow Nematic Fluctuations in BaFe$_2$As$_2$Aug 07 2017Sep 19 2017An instrumentation problem with the signal acquisition at high frequencies was discovered and we no longer believe that the experimental data presented in the manuscript, showing a frequency enhancement of the elastoresistivity, are correct. After correcting ... More
Theory of Correlated Pairs of Electrons Oscillating in Resonant Quantum States to Reach the Critical Temperature in a MetalJul 10 2017The formation of Correlated Electron Pairs Oscillating around the Fermi level in Resonant Quantum States (CEPO-RQS), when a metal is cooled to its critical temperature T=Tc, is studied. The necessary conditions for the existence of CEPO-RQS are analyzed. ... More
Quantitative characterization of the nanoscale local lattice strain induced by Sr dopants in La$_{1.92}$Sr$_{0.08}$CuO$_4$Jul 03 2017The nanometer scale lattice deformation brought about by the dopants in high temperature superconducting cuprate La$_{2-x}$Sr$_x$CuO$_4$(x=0.08) was investigated by measuring the associated X-ray diffuse scattering around multiple Bragg peaks. A characteristic ... More
Quenching current by flux-flow instability in iron-chalcogenides thin filmsJun 02 2017The stability against quench is one of the main issue to be pursued in a superconducting material which should be able to perform at very high levels of current densities. Here we focus on the connection between the critical current $I_c$ and the quenching ... More