Related papers: Modulation of pairing interaction in Bi$_2$Sr$_2$C…
Single atom manipulation within doped correlated electron systems would be highly beneficial to disentangle the influence of dopants, structural defects and crystallographic characteristics on their local electronic states. Unfortunately,…
Recent experiments on Bi-based cuprate superconductors have revealed an unexpected enhancement of the pairing correlations near the interstitial oxygen dopant ions. Here we propose a possible mechanism -- based on local screening effects --…
New break-junction tunneling data are reported in Bi2Sr2CaCu2O(8+delta) over a wide range of hole concentration from underdoped (Tc = 74 K) to optimal doped (Tc = 95 K) to overdoped (Tc = 48 K). The conductances exhibit sharp dips at a…
The mechanism of Cooper pair formation in iron-based superconductors remains a controversial topic. The main question is whether spin or orbital fluctuations are responsible for the pairing mechanism. To solve this problem, a crucial clue…
The cuprate material BSCCO-2212 is believed to be doped by a combination of cation switching and excess oxygen. The interstitial oxygen dopants are of particular interest because scanning tunnelling microscopy (STM) experiments have shown…
Scanning tunneling spectroscopy (STS) studies reveal long-range spatial homogeneity and predominantly $d_{x^2-y^2}$-pairing spectral characteristics in under- and optimally doped $\rm YBa_2Cu_3O_{7-\delta}$ superconductors, whereas STS on…
Using ultrafast optical techniques, we detect two types of bosons strongly coupled to electrons in the family of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ from the underdoped to overdoped regimes. The different doping dependences of the…
In this paper we summarize our STM studies of the density of electronic states in nearly optimally doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ in zero field. We report on the inhomogeneity of the gap structure, density of states modulations…
We present results of density functional theory (DFT) calculation of the structural supermodulation in BSCCO-2212 structure, and show that the supermodulation is indeed a spontaneous symmetry breaking of the nominal crystal symmetry, rather…
Doping dependence of the superconducting state structure and spin-fluctuation pairing mechanism in the $Ba(Fe_{1-x}Co_{x})_{2}As_{2}$ family is studied. BCS-like analysis of experimental data shows that in the overdoped regime, away from…
The electrical, magnetic, thermal and optical characteristics of Gallium (Ga) doped silicene are investigated using density functional theory (DFT). The effect of doping is studied by tuning dopant concentrations as well as examining varied…
Fluctuating superconductivity - vestigial Cooper pairing in the resistive state of a material - is usually associated with low dimensionality, strong disorder or low carrier density. Here, we report single particle spectroscopic,…
The superconducting state of a two-dimensional d-p model is studied from the spin fluctuation point of view by using a strong coupling theory. The fluctuation exchange (FLEX) approximatoin is employed to calculate the spin fluctuations and…
We study the interplay of fluctuations and superconductivity in BaFe$_2$As$_2$ (Ba-122) compounds with Ba and Fe substituted by K ($p$ doping) and Co ($n$ doping), respectively. To this end we measured electronic Raman spectra as a function…
Bi-based cuprate superconductors are important materials for both fundamental research and applications. As in other cuprates, the superconducting phase in the Bi compounds lies close to an antiferromagnetic phase. Our density functional…
The oxygen dopants are essential in tuning electronic properties of Bi$_2$Sr$_2$Ca$_{n-1}$Cu$_n$O$_{2n+4+\delta}$ superconductors. Here we apply the technique of scanning tunneling microscopy and spectroscopy to study the influence of…
A Hamiltonian H(\Gamma) applicable to cuprate HTS, with a doping dependent pairing interaction \Gamma(x) = V(x) + U(x), is linked to a Cu3d-O2p state probability model(SPM). A consequence of doping induced electron hopping, the SPM mandates…
Recent scanning tunneling spectroscopy experiments have provided evidence that dopant impurities in high- Tc superconductors can strongly modify the electronic structure of the CuO2 planes nearby, and possibly influence the pairing. To…
We study the inhomogeneity of the electronic pairing gap observed by STM near the surface of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ to be correlated with interstitial O defects. We treat the problem in a slave boson mean field theory of a…
Recently using Scanning Josephson Tunneling Microscopy (SJTM) in the group of S\'eamus Davis a super-modulation of the superconducting order parameter induced by super-modulation of the distance $\delta$ between planar Cu and apical O was…