Related papers: Distinct charge and spin gaps in underdoped YBa2Cu…
Underdoped high-Tc superconductors are frequently characterised by a temperature, T*, below which the normal-state pseudogap opens. Two different "phase diagrams" based on the doping (p) dependence of T* are currently considered: one where…
In NdBa_2[Cu_{1-y}Ni_y]_3O_{7-\delta}, magnetic Ni-impurities suppress Tc but at the same time the pseudogap is strongly enhanced. This unique feature makes it an ideal system to study possible relations between the anomalous Nernst effect,…
We report optical reflectivity study on Nd$_{2-x}$Ce$_x$CuO$_4$ over a broad doping range 0$\leq x\leq$0.20. The study reveals a systematic shift of chemical potential with doping. A pronounced peak structure specific to the electron-doped…
Superconductivity in copper oxides emerges on doping holes or electrons into their Mott insulating parent compounds. The spin excitations are thought to be the mediating glue for the pairing in superconductivity. Here the momentum and…
Optical spectroscopy was used to investigate the optical gap (2$\Delta $) due to charge ordering (CO) and related pseudogap developments with x and temperature (T) in La$_{1-x}$Ca$_{x}$MnO$_{3}$ (0.48 <= x <= 0.67). Surprisingly, we found…
Superconductivity in cuprates is achieved by doping holes into a correlated charge-transfer insulator. While the correlated character of the parent insulator is now understood, there is no accepted theory for the "normal" state of the doped…
Zero-field muon spin relaxation (ZF-$\mu$SR) measurements were undertaken on under- and overdoped samples of superconducting YBa$_2$Cu$_3$O$_{6+x}$ to determine the origin of the weak static magnetism recently reported in this system. The…
Ultrafast time-resolved photoinduced reflectivity is measured for the itinerant antiferromagnet UNiGa$_{5}$ ($T_{N} \approx$85 K) from room temperature to 10 K. The relaxation time $\tau$ shows a sharp increase at $T_{N}$ consistent with…
A spin-singlet ground state with a spin gap has been discovered in antiferromagnetic spin chain substances when the spin value is 1/2, 1 or 2. To find spin gap (singlet-triplet) excitations in spin-3/2 chain substances, we performed…
We provide a new perspective on the pseudogap physics for attractive fermions as described by the three-dimensional Hubbard model. The pseudogap in the single-particle spectral function, which occurs for temperatures above the critical…
We report results of a muon spin relaxation study of slow magnetic fluctuations in the pseudogap phase of underdoped single-crystalline YBa$_{2}$Cu$_{3}$O$_{y}$, $y = 6.77$ and 6.83. The dependence of the dynamic muon spin relaxation rate…
To investigate the relationship between the pseudogap and superconductivity, we measured both the in-plane ($\rho_{ab}$) and out-of-plane ($\rho_c$) resistivity for oxygen-controlled Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ single crystals…
The spin-liquid phase of two highly frustrated pyrochlore magnets Gd2Ti2O7 and Gd2Sn2O7 is probed using electron spin resonance in the temperature range 1.3 - 30 K. The deviation of the absorption line from the paramagnetic position \nu…
We report angle-resolved photoemission spectra both above and below T_c in the single-plane cuprate superconductor Bi_2Sr_{2-x}La_xCuO_{6+d}. The superconducting state measurements show a highly anisotropic excitation gap with a maximum…
We report a comparative study of 63Cu Nuclear Magnetic Resonance spin lattice relaxation rates, T_1^{-1}, on undoped SrCuO_2 and Ca doped Sr_{0.9}Ca_{0.1}CuO_2 spin chain compounds. A temperature independent T_1^{-1} is observed for SrCuO_2…
Muon spin rotation ({\mu}+SR) measurements of square-root second moments of local magnetic fields {\sigma} in superconducting mixed states, as published for oriented crystals and powder samples of YBa2Cu3O7-{\delta} ({\delta} {\approx}…
In the search for the mechanism of high-temperature superconductivity, intense research has been focused on the evolution of the spin excitation spectrum upon doping from the antiferromagnetic insulating to the superconducting states of the…
The low-energy excitations of the lightly doped cuprates were studied by angle-resolved photoemission spectroscopy. A finite gap was measured over the entire Brillouin zone, including along the d_{x^2 - y^2} nodal line. This effect was…
We investigate the microscopic origin of the pseudogap in the weakly doped 2D Hubbard model using Quantum Monte Carlo within the dynamical cluster approximation. We compare our results with proposed scenarios for the pseudogap. All our…
The dependence of the superconducting gaps in epitaxial Ba(Fe_{1-x}Co_{x})_2As_2 thin films on the nominal doping x (0.04 \leq x \leq 0.15) was studied by means of point-contact Andreev-reflection spectroscopy. The normalized conductance…