139 research outputs found
Imaging Spatial Ordering of the Oxygen Chains in at the Insulator-to-Metal Transition
No full textIt is known that the mobile oxygen ions, y, in the basal plane of YBa2Cu3O6+y (0.33<y<0.67) form oxygen chains needed to create the metallic phase in the CuO2 layers. Here we visualize the spatial organization of oxygen chains in a crystal of YBa2Cu3O6+y very close to the insulator-to-superconductor transition with y=0.33 (T c =7 K). The distribution of oxygen defects chains has been obtained by performing scanning micro X-ray diffraction measurements. This experiment provides mixed real and reciprocal space information. We found a granular spatial pattern due to the oxygen chains being segregated in nanoscale puddles with ortho-II crystallographic structure embedded in an insulating matrix of disordered oxygen ions
Competing striped structures in La2CuO4+y
No full textHigh temperature superconductivity emerges in unique materials, like cuprates, that belong to the class of heterostructures at atomic limit, made of a superlattice of
superconducting atomic layers intercalated by spacer layers. The physical properties of a strongly correlated electronic system, emerge from the competition between different
phases with a resulting inhomogeneity from nanoscale to micron scale. Here, we focus on the spatial arrangements of two types of structural defects in the cuprate La2CuO4+y :
(i) the local lattice distortions in the CuO2 active layers and (ii) the lattice distortions around the charged chemical dopants in the spacer layers. We use a new advanced microscopy method: scanning nano X-ray diffraction (nXRD). We show here that local lattice distortions form incommensurate nanoscale ripples spatially anticorrelated with puddles of self-organized chemical dopants in the spacer layers
Aspetti immunoistochimici e ultrastrutturali della biopsia cutanea nel diabete insulino-dipendente
No full text
Superconducting qubit based on twisted cuprate van der Waals heterostructures.
No full textVan-der-Waals assembly enables the fabrication of novel Josephson junctions featuring an atomically sharp interface between two exfoliated and relatively twisted
Bi
2
Sr
2
CaCu
2
O
8
+
x
(Bi2212) flakes. In a range of twist angles around 45°, the junction provides a regime where the interlayer two-Cooper pair tunneling dominates the current-phase relation. Here we propose employing this novel junction to realize a capacitively shunted qubit that we call flowermon. The
d
-wave nature of the order parameter endows the flowermon with inherent protection against charge-noise-induced relaxation and quasiparticle-induced dissipation. This inherently protected qubit paves the way to a new class of high-coherence hybrid superconducting quantum devices based on unconventional superconductors
Two-Dimensional Nanogranularity of the Oxygen Chains in the YBa2Cu3O6.33 Superconductor
No full textThe organization of dopants in high-temperature superconductors provides complex topological geometries that control superconducting properties. This makes the study of dopants’ spatial distribution of fundamental importance. The mobile oxygen ions, y, in the CuO2 plane of YBa2Cu3O6 + y (0.33 < y < 0.67) form ordered chains which greatly affect the transport properties of the material. Here, we visualize and characterize the two-dimensional spatial organization of these oxygen chains using scanning micro X-ray diffraction measurements in transmission mode on a thin single-crystal slab with y = 0.33 (T c = 7 K) near the critical doping for the insulator-to-metal transition. We show the typical landscape of percolation made of a granular spatial pattern due the oxygen chains segregating in quasi-one-dimensional needles of ortho-II (O-II) phase embedded in an insulating matrix with low density of disordered oxygen interstitials
Phase Separation in Electron Doped Iron-Selenide K0.8Fe1.6Se2 Superconductor by Scanning X-ray Nano-Diffraction
No full textA new family of high temperature superconductors, the heavily electron doped iron-selenides, like K0.8Fe1.6Se2, has been attracting high interest since they show both 30 K superconductivity, with missing hole pockets questioning the s± pairing model, and unusually high magnetic moments. The hot debate is between coexistence versus phase separation and on the possible divergence of surface from bulk structure. Here, we provide direct evidence for a nanoscale phase separation in a single crystal of K0.8Fe1.6Se2, where a first magnetic phase, with superlattice modulation (5–√×5–√) , coexists with a second nonmagnetic phase, with a second superlattice modulation ( 2–√×2–√ ), below 520 K using transmission X-ray diffraction. The mapping of the spatial distribution of the two phases is measured by scanning X-ray nanodiffraction using a 300×300 nm2 X-ray spot. The complex spatial phase separation clarifies the coexistence of superconductivity and magnetism in the same sample
Effect of sperm morphology and motile sperm count on outcome of intrauterine insemination in oligozoospermia and/or asthenozoospermia
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