Related papers: Enhanced superfluid density on twin boundaries in …
Measurements of the current-voltage characteristics were performed on Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ single crystals with doping level $0.044 \leq x \leq 0.1$. An unconventional increase in the flux-flow resistivity $\rho_{\rm ff}$ with…
It was recently shown that the vacuum in the background of a strong enough magnetic field may become an electromagnetic superconductor due to interplay between strong and electromagnetic forces. The superconducting ground state of the…
High-resolution scanning superconducting quantum interference device (SQUID) microscopy was used to study the flux quantization phenomenon in multiply-connected anisotropic high-Tc NdBa2Cu3O7-d single crystalline thin films. The spatial…
We study the interplay of magnetic and superconducting order in single crystalline hole doped Ba1-xNaxFe2As2 using muon spin relaxation. We find microscopic coexistence of magnetic order and superconductivity. In a strongly underdoped…
We report systematic studies of structural, microstructural and transport properties of Y1-xCaxBa2Cu3O7-d bulk samples with 0.20 x 0.0. The partial substitution of Ca2+ at Y3+ site in YBa2Cu3O7-d leads towards slightly overdoped regime,…
We study systematically transport, susceptibility and heat capacity for BaFe$_{2-x}$Co$_x$As$_2$ single crystals. In the underdoped region, spin density wave (SDW) transition is observed in both resistivity and susceptibility. The magnetic…
Nano-fabricated superconducting quantum interference device (nano-SQUID) is a direct and sensitive flux probe useful for magnetic imaging of quantum materials and mesoscopic devices. Enabled by functionalities of superconductive integrated…
An intriguing aspect of unconventional superconductivity is that it always appears in the vicinity of other competing phases, whose suppression brings the full emergence of superconductivity. In the iron-pnictides, these competing phases…
We have investigated the magnetization properties and flux dynamics of superconducting Cu$_x$TiSe$_2$ single crystals within wide range of copper concentrations. We find that the superconducting anisotropy is low and independent on copper…
The nature of spin-density wave and its relation with superconductivity are crucial issues in the newly discovered Fe-based high temperature superconductors. Particularly it is unclear whether the superconducting phase and spin density wave…
Here we use global and local magnetometry and Hall probe imaging to investigate the electromagnetic connectivity of the superconducting current path in the oxygen-deficient fluorine-free Nd-based oxypnictides. High resolution transmission…
In type-1.5 superconductors, vortices emerge in clusters, which grow in size with increasing magnetic field. These novel vortex clusters and their field dependence are directly visualized by scanning SQUID microscopy at very low vortex…
Single crystals of A$_{1-x}$K$_x$Fe$_2$As$_2$ (A=Ba, Sr) with high quality have been grown successfully by FeAs self-flux method. The samples have sizes up to 4 mm with flat and shiny surfaces. The X-ray diffraction patterns suggest that…
Scanning SQUID imaging of CaSb$_2$ reveals dense vortex clusters with enhanced boundary susceptibility and suppressed internal vortex motion, which features inconsistent with both isolated vortex and flux tube behaviors. These measurements…
In-plane complex surface impedance of a Bi2Sr2CaCu2Oy single crystal was measured in the mixed state at 40.8 GHz.The surface reactance, which is proportional to the real part of the effective penetration depth, increased rapidly just above…
We report a doping dependent electronic Raman scattering measurements on iron-pnictide superconductor Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ single crystals. A strongly anisotropic gap is found at optimal doping for x=0.065 with $\Delta_{max}\sim…
We present very low temperature Scanning Tunneling Microscopy and Spectroscopy (STM/S) measurements of a W based amorphous thin film grown with focused-ion-beam. In particular, we address the superconducting properties close to the border,…
In a superconducting ferromagnet, the superconducting state appears in the ferromagnetic phase where usually a domain structure has already developed. We study the influence of the superconducting screening currents on a stripe structure…
Recent measurements of the superconducting penetration depth in Ba(Fe_1-x Co_x)2As2 appeared to disagree on the magnitude and curvature of {\Delta}{\lambda}_{ab}(T), even near optimal doping. These measurements were carried out on different…
The interrelation between heterogeneity and flux pinning is studied in Ba(Fe1-xCox)2As2 single crystals with widely varying Co-content x. Magnetic Bitter decoration of the superconducting vortex ensemble in crystals with x = 0:075 and x =…