Seiki Komiya

Electrical resistivity anisotropy from self-organized one dimensionality in high-temperature superconductors

We investigate the manifestation of stripes in the in-plane resistivity anisotropy in untwinned single crystals of La2-xSrxCuO4 ( x = 0.02-0.04) and YBa(2)Cu(3)O(y) ( y = 6.35-7.0). It is found that both systems show strongly temperature-dependent in-plane anisotropy in the lightly hole-doped region and that the anisotropy in YBa(2)Cu(3)O(y) grows with decreasing y below approximately 6.60 despite the decreasing orthorhombicity, which gives most direct evidence that electrons self-organize into a macroscopically anisotropic state. The transport is found to be easier along the direction of the spin stripes already reported, demonstrating that the stripes are intrinsically conducting in cuprates.

Mobility of the doped holes and the antiferromagnetic correlations in underdoped high- Tc cuprates.

The emergence and the evolution of the metallic charge transport in the La2-xSrxCuO4 system from lightly to optimally doped samples (x = 0.01-0.17) are studied. We demonstrate that in high-quality single crystals the in-plane resistivity shows a metallic behavior for all values of x at moderate temperatures and that the hole mobility at 300 K changes only by a factor of 3 from x = 0.01 to 0.17, where its x dependence is found to be intriguingly similar to that of the inverse antiferromagnetic correlation length. We discuss an incoherent-metal picture and a charged-stripe scenario as candidates to account for these peculiar features.

Electronic phase diagram of High-Tc cuprate superconductors from a mapping of the in-plane resistivity curvature

We propose that resistivity curvature mapping (RCM) based on the in-plane resistivity data is a useful way to objectively draw electronic phase diagrams of high-Tc cuprates, where various crossovers are important. In particular, the pseudogap crossover line can be conveniently determined by RCM. We show experimental phase diagrams obtained by RCM for Bi2Sr2-zLazCuO6+delta, La2-xSrxCuO4, and YBa2Cu3Oy, and demonstrate the universal nature of the pseudogap crossover. Intriguingly, the electronic crossover near optimum doping depicted by RCM appears to occur rather abruptly, suggesting that the quantum-critical regime, if it exists, must be very narrow.

Diamagnetism and Cooper pairing above T c in cuprates

In the cuprate superconductors, Nernst and torque magnetization experiments have provided evidence that the disappearance of the Meissner effect at

A UNIVERSAL SCALING RELATION IN HIGH-TEMPERATURE SUPERCONDUCTORS

{T}_{c}

Evolution of the Hall Coefficient and the Peculiar Electronic Structure of the Cuprate Superconductors

is caused by the loss of long-range phase coherence, rather than the vanishing of the pair condensate. Here we report a series of torque magnetization measurements on single crystals of

Low-energy electronic structure of the high-Tc cuprates La2−xSrxCuO4 studied by angle-resolved photoemission spectroscopy

{\text{La}}_{2\ensuremath{-}x}{\text{Sr}}_{x}{\text{CuO}}_{4}

Epitaxial Growth of FeSe0.5Te0.5 Thin Films on CaF2 Substrates with High Critical Current Density

(LSCO),

Universal versus Materials-Dependent Two-Gap Behaviour of the High-Tc Cuprate Superconductors: Angle-Resolved Photoemission Study of La2-xSrxCuO4

{\text{Bi}}_{2}{\text{Sr}}_{2\ensuremath{-}y}{\text{La}}_{y}{\text{CuO}}_{6}

Antiferromagnets: Magnetic shape-memory effects in a crystal

(Bi 2201),