Related papers: Cooper Pair Breakup in YBCO under Strong Terahertz…
The in-plane thermal conductivity K(T) of Zn-doped YBCO single crystals (YBCO:Zn) has been investigated in the temperature range from 5 to 250 K and in magnetic fields up to 30 kOe. The thermal conductivity decreases substantially with…
Terahertz power dependence of the photoresponse of field effect transistors, operating at frequencies from 0.1 to 3 THz for incident radiation power density up to 100 kW/cm^2 was studied for Si metal-oxide-semiconductor field-effect…
We apply a recently-developed low-field technique to inductively measure the critical pair momentum $p_c$ in thin, underdoped films of Y$_{1-x}$Ca$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-\delta}$ and Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ reflecting a…
We propose a model for high-Tc superconductors that includes both the spin fluctuations of the Cu++ magnetic ions and of the spins of O-- doped holes (spinons). The charge of the dopants (holons) is associated to quantum skyrmion…
In superconductors, electrons bound into Cooper pairs conduct a dissipationless current. The strength of the Cooper pairs scales with the value of the critical transition temperature (Tc). In cuprate high-Tc superconductors, however, the…
The two-flavor color superconductivity is examined over a wide range of baryon density with a single model. To study the structural change of Cooper pairs, quark correlation in the color superconductor is calculated both in the momentum…
We have grown and characterized 30 nm thick YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) films, deposited by pulsed laser deposition on both MgO (110) and SrTiO$_3$ (001) substrates, which induce opposite strain to the superconducting layer. By…
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…
The existence of coherent magnetic correlations in the normal phase of cuprate high-temperature superconductors has proven difficult to measure directly. Here we report on a study of ferromagnetic-superconductor bilayers of…
We report on the growth and characterization of ultrathin YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) films on MgO (110) substrates, which exhibit superconducting properties at thicknesses down to 3 nm. YBCO nanowires, with thicknesses down to 10 nm…
Although initially quite controversial, it has been widely accepted that the Cooper pairs in optimally doped cuprate superconductors have predominantly dx2-y2 wavefunction symmetry. The controversy has now shifted to whether the high-Tc…
The thermodynamics of the superconducting transition is studied as a function of doping using high-resolution expansivity data of YBa2Cu3Ox single crystals and Monte-Carlo simulations of the anisotropic 3D-XY model. We directly show that Tc…
Suppression of superconductivity due to the proximity effect between a superconductor and a ferromagnet can be partially alleviated when a Cooper pair simultaneously samples different directions of the short-range exchange field. The…
Polar Kerr effect in the high-Tc superconductor \YBCO was measured at zero magnetic field with high precision using a cyogenic Sagnac fiber interferometer. We observed non-zero Kerr rotations of order $\sim 1 \mu$rad appearing near the…
Recent experiments in the original cuprate high temperature superconductor, La$_2-x$Ba$_x$CuO$_4$, have revealed a remarkable sequence of transitions [1]. Here we investigate such crystals with Kerr effect which is sensitive to…
Here we report an optical investigation in the terahertz region of a 40 nm ultrathin BaFe$_{1.84}$Co$_{0.16}$As$_2$ superconducting film with superconducting transition temperature T$_c$ = 17.5 K. A detailed analysis of the combined…
We have measured the spin fluctuations in the YBa2Cu3O6.5 (YBCO6.5, Tc=59 K) superconductor at high-energy transfers above ~ 100 meV. Within experimental error, the momentum dependence is isotropic at high-energies, similar to that measured…
The complex conductivity of underdoped and optimally doped YBa$_2$Cu$_3$O$_{7-\delta}$ samples and overdoped similar compound Y$_{0.7}$Ca$_{0.3}$Ba$_2$Cu$_3$O$_{7-\delta}$ was measured using time-domain terahertz spectroscopy. In the normal…
We analyze microscopically a Cooper pair splitting device in which a central superconducting lead is connected to two weakly coupled normal leads through a carbon nanotube. We determine the splitting efficiency at resonance in terms of…
For an electron gas with a $ \delta $-function attraction we investigate the crossover from weak-coupling to strong-coupling superconductivity as well as normal state near the temperature $T^*$, at which the strong coupling produces a…