Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userDisappearance of zinc impurity resonance in large gap region on Bi$_{mathrm{2}}$Sr$_{mathrm{2}}$CaCu$_{mathrm{2}}$O$_{mathrm{8+}delta}$ probed by scanning tunneling spectroscopy
123
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Using Scanning tunneling spectroscopy (STS), we report the correlation between spatial gap inhomogeneity and the zinc (Zn) impurity resonance in single crystals of Bi$_{mathrm{2}}$Sr$_{mathrm{2}}$Ca(Cu$_{mathrm{1-}x}$Zn$_{x}$)$_{mathrm{2}}$O$_{mathrm{8+}delta}$ with different carrier (hole) concentrations ($p$) at a fixed Zn concentration ($x$ $sim$ 0.5 % per Cu atom). In all the samples, the impurity resonance lies only in the region where the gap value is less than $sim$ 60 meV. Also the number of Zn resonance sites drastically decreases with decreasing $p$, in spite of the fixed $x$. These experimental results lead us to a conclusion that the Zn impurity resonance does not appear in the large gap region although the Zn impurity evidently resides in this region.
rate research
Read More
We show that the observed time-reversal symmetry breaking (TRSB) of the superconducting state in $mathrm{Sr}_{2}mathrm{Ru}mathrm{O}_{4}$ can be understood as originating from inhomogeneous strain fields near edge dislocations of the crystal. Specifically, we argue that, without strain inhomogeneities, $mathrm{Sr}_{2}mathrm{Ru}mathrm{O}_{4}$ is a single-component, time-reversal symmetric superconductor, likely with $d_{x^{2}-y^{2}}$ symmetry. However, due to the strong strain inhomogeneities generated by dislocations, a slowly-decaying sub-leading pairing state contributes to the condensate in significant portions of the sample. As it phase winds around the dislocation, time-reversal symmetry is locally broken. Global phase locking and TRSB occur at a sharp Ising transition that is not accompanied by a change of the single-particle gap and yields a very small heat capacity anomaly. Our model thus explains the puzzling absence of a measurable heat capacity anomaly at the TRSB transition in strained samples, and the dilute nature of the time-reversal symmetry broken state probed by muon spin rotation experiments. We propose that plastic deformations of the material may be used to manipulate the onset of broken time-reversal symmetry.
We investigated SrFe$mathrm{_2}$(As$mathrm{_{1-x}}$P$mathrm{_x}$)$mathrm{_2}$ single crystals with four different phosphorus concentrations x in the superconducting phase (x = 0.35, 0.46) and in the magnetic phase (x = 0, 0.2). The superconducting samples display a V-shaped superconducting gap, which suggests nodal superconductivity. Furthermore we determined the superconducting coherence length by measuring the spatially resolved superconducting density of states (DOS). Using inelastic tunneling spectroscopy we investigated excitations in the samples with four different phosphorus concentrations. Inelastic peaks are related to bosonic modes. Phonon and non-phonon mechanism for the origin of these peaks are discussed.
We report comprehensive temperature and doping-dependences of the Raman scattering spectra for $mathrm{BaFe_{2}}(mathrm{As}_{1-x}mathrm{P}_{x}mathrm{)_{2}}$ ($x =$ 0, 0.07, 0.24, 0.32, and 0.38), focusing on the nematic fluctuation and the superconducting responses. With increasing $x$, the bare nematic transition temperature estimated from the Raman spectra reaches $T =$ 0 K at the optimal doping, which indicates a quantum critical point (QCP) at this composition. In the superconducting compositions, in addition to the pair breaking peaks observed in the $A_{mathrm{1g}}$ and $B_{mathrm{1g}}$ spectra, another strong $B_{mathrm{1g}}$ peak appears below the superconducting transition temperature which is ascribed to the nematic resonance peak. The observation of this peak indicates significant nematic correlations in the superconducting state near the QCP in this compound.
In conventional superconductors, magnetic impurities form an impurity band due to quantum interference of the impurity bound states, leading to suppression of the superconducting transition temperature. Such quantum interference effects can also be expected in d-wave superconductors. Here, we use scanning tunneling microscopy to investigate the effect of multiple non-magnetic impurities on the local electronic structure of the high-temperature superconductor Bi$_{2}$Sr$_{2}$Ca(Cu$_{1-x}$Zn$_{x}$)$_{2}$O$_{8+delta}$. We find several fingerprints of quantum interference of the impurity bound states including: (i) a two-dimensional modulation of local density-of-states with a period of approximately 5.4 AA along the $a$- and $b$-axes, which is indicative of the d-wave superconducting nature of the cuprates; (ii) abrupt spatial variations of the impurity bound state energy; (iii)an appearance of positive energy states; (iv) a split of the impurity bound state. All of these findings provide important insight into how the impurity band in d-wave superconductors is formed.
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, their high diffusion barrier prevents conventional manipulation techniques. Here, we demonstrate the possibility to reversibly manipulate select sites in the optimally doped high temperature superconductor Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$ using the local electric field of the tip. We show that upon shifting individual Bi atoms at the surface, the spectral gap associated with superconductivity is seen to reversibly change by as much as 15 meV (~5% of the total gap size). Our toy model that captures all observed characteristics suggests the field induces lateral movement of point-like objects that create a local pairing potential in the CuO2 plane.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
