Related papers: Tunneling spectroscopy of $s\pi$ pairing state as …
A major question in Fe-based superconductors remains the structure of the pairing, in particular whether it is of unconventional nature. The electronic structure near vortices can serve as a platform for phase-sensitive measurements to…
We investigate single-particle excitation properties in the normal state of a two-band superconductor or superfluid throughout the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein-condensation (BEC) crossover, within the many-body T-matrix…
Inhomogeneity is introduced through random local interactions (Ui) in an attractive Hubbard model on a square lattice and studied using mean-field Bogoliubov-de Gennes formalism. Superconductivity is found to get suppressed by the random Ui…
We develop a method to solve the Bogoliubov de Gennes equation for superconductors self-consistently, using the recursion method. The method allows the pairing interaction to be either local or non-local corresponding to s and d-wave…
We discuss the tunneling spectroscopy at a surface in multi-band systems such as Fe-based superconductors with the use of the quasiclassical approach. We extend the single-band method by Matsumoto and Shiba [J. Phys. Soc. Jpn. 64, 1703…
The low energy band structure of the FeAs based superconductors is fitted by a tight binding model with two Fe ions per unit cell and two degenerate orbitals per Fe ion. Based on this, superconductivity with extended s-wave pairing symmetry…
Superconductivity is achieved by the pairing of electrons and phase coherence between the Cooper pairs. According to the Bardeen-Cooper-Schrieffer theory, the quasiparticles with Bogoliubov dispersion exists and reveal particle-hole…
The pseudogap state is one of the peculiarities of the cuprate high temperature superconductors. Here we investigate its presence in BaCo$_{x}$Fe$_{2-x}$As$_{2}$, a member of the pnictide family, with temperature dependent scanning…
We study the Josephson effect in $s_{\pm}/I/s_{\pm}$ junctions made by two bands reversed sign s-wave ($s_{\pm}$) superconductive materials. We derive an equation providing the bound Andreev energy states parameterized by the band ratio…
Considering a possibility that the pseudogap state in the underdoped high-$T_{c}$ superconductors is not due to a superconducting correlation, we study the tunneling spectroscopy below $T_{c}$ based on the phenomenological models of the…
We study the phase fluctuations in the normal state of generic two-dimensional superconducting systems with s-wave pairing. The effect of phase fluctuations of the pairing fields can be dealt with perturbatively using disorder averaging,…
We present the synthesis and the tunneling spectroscopy study of superconducting FeSe0.5Te0.5 (Tc = 14 K), SmFeAsO0.85 (Tc = 45 K) and SmFeAsO0.9F0.1 (Tc = 52 K). The samples were characterized by Rietveld refinement of X-ray diffraction…
In the first three years since the discovery of Fe-based high Tc superconductors, scanning tunneling microscopy (STM) and spectroscopy have shed light on three important questions. First, STM has demonstrated the complexity of the pairing…
The quantum condensate of Cooper-pairs forming a superconductor was originally conceived to be translationally invariant. In theory, however, pairs can exist with finite momentum $Q$ and thereby generate states with spatially modulating…
Unconventional superconductivity often competes or coexists with other electronic orders. In iron-based superconductors, relationship between superconductivity and the nematic state, where the lattice rotational symmetry is spontaneously…
Since the discovery of iron-based superconductors, a number of theories have been put forward to explain the qualitative origin of pairing, but there have been few attempts to make quantitative, material-specific comparisons to experimental…
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…
For the newly discovered ironbased superconductors we propose a one band model for conduction band with first and secondnearestneighbor electron hoppings with two types of d wave and three types of s wave pairing symmetries for the…
Motivated by the recently discovered time-reversal symmetry-breaking superconductivity in epitaxial Bi/Ni bilayer system with transition temperature $T_c\approx 4.2$K and the observation of zero-bias anomaly in tunneling measurements, we…
We present measurements of the superconducting gap of URu$_2$Si$_2$ made with scanning tunneling microscopy (STM) using a superconducting tip of Al. We find tunneling conductance curves with a finite value at the Fermi level. The density of…