Inhomogeneity of charge-density-wave order and quenched disorder in a high-Tc superconductor

Abstract

It has recently been established that the high temperature (high-Tc(between atomic and macroscopic scale). Here we report micro X-ray diffraction imaging of the spatial distribution of both the charge-density-wave 'puddles' (domains with only a few wavelengths) and quenched disorder in HgBa 2 CuO 4+y , the single layer cuprate with the highest T c , 95 kelvin [26][27][28] . We found that the charge-density-wave puddles, like the steam bubbles in boiling water, have a fat-tailed size distribution that is typical of selforganization near a critical point 19 . However, the quenched disorder, which arises from oxygen interstitials, has a distribution that is contrary to the usual assumed random, uncorrelated distribution 12, 13 . The interstitials-oxygen-rich domains are spatially anticorrelated with the charge-density-wave domains, leading to a complex emergent geometry of the spatial landscape for superconductivity. 2Although it is known that the incommensurate charge-density-wave (CDW) order in cuprates (copper oxides) is made of ordered, stripy, nanoscale puddles with an average of only 3-4 oscillations, information about the size distribution and spatial organization of these puddles has so far not been available. We present experiments that demonstrate that CDW puddles, have a complex spatial distribution and coexist with, but are spatially anticorrelated to, quenched disorder in HgBa 2 CuO 4+y (Hg1201). The sample we studied is a layered perovskite at optimum doping with oxygen interstitials y=0.12, tetragonal symmetry P4/mmm and a low misfit strain [14][15][16] . The X-ray diffraction (XRD) measurements (see Methods) show diffuse CDW satellites (secondary peaks surrounding a main peak) at q CDW =(0.23a*, 0.16c*), in the b*=0 plane and q CDW =(0.23b*, 0.16c*) in the a*=0 plane (where a*, b*, and c* are the reciprocal lattice units) around specific Bragg peaks, such as (1 0 8), below the onset temperature T CDW =240 K (see Fig. 1a). The component of the momentum transfer q CDW in the CuO 2 plane (0.23a*) in this case is smaller than it is in the underdoped case (0.28a*) 5 . The temperature evolution of CDW-peak profile along a* (in the h direction; Fig. 1b) shows a smeared, glassy-like evolution below T CDW .The CDW-peak intensity reaches a maximum at T=100 K, followed by a drop associated with the onset of superconductivity at T=T c . We investigated the isotropic character of the CDW, in the a-b plane using azimuthal scans, as shown in Fig. 1c. We observed an equal probability of vertical and horizontally striped CDW puddles.Our main result is the discovery of the statistical spatial distribution of the CDW-puddle size and density throughout the sample, which shows an emergent complex network geometry for the superconducting phase. We performed scanning micro X-ray diffraction (SµXRD) measurements (see Methods) to extend the imaging of spatial inhomogeneity previously obtained by scanning tunneling microscopy [7][8][9] , from the surface to the bulk of the sample and from nanoscale to mesoscale spatial inh...

Nanoscale Superconducting Honeycomb Charge Order in IrTe2

“…The relationship between the charge order and the superconductivity is not a simple mutual exclusion as also noticed very recently for high temperature superconductivity 44 . Moreover, this…”

Two-Dimensional Nanogranularity of the Oxygen Chains in the YBa2Cu3O6.33 Superconductor

“…These inhomogeneous phases are due to the ordering of dopants and competition between short range charge, spin and orbital density wave order (CDW, SDW, ODW) inhomogeneity. As a result, new complex geometries emerge, where quantum coherence develops [12][13][14]. Thus, the study of local features by using high resolution experimental probes assumes a paramount importance for the a deeper understanding of new complex and heterogeneous materials.…”

“…The collected data, treated by spatial statistical tools, have shown the formation of fractal patterns of interstitial oxygens ordered domains in LCO [21], intrinsic phase separation in doped iron-chalcogenides [22,23] and planar symmetry breaking in Bismuthates [24]. More recently, it's has been demonstrated that the quenched disorder due to dopants is spatially anticorrelated with electronic textures and/or local lattice distortions in Hg1201 [12,13] and LCO [25]. Thus, the oxygen striped domains are candidate to provide the space where superconductivity arises.…”

“…Therefore it is possible that the spatial topology for the emergence of high temperature superconductivity is given by the interface space between the one dimensional O-II needles with can give a hyperbolic space [12,13].…”

Effect of spacer layer on flux-pinning properties of iron-based superconductors

“…The misfit strain between the spacer layers on the FeAs layers occurs [13] inducing an anisotropic internal pressure on the FeX layers which together with a proximity to a Lifshitz transition driven by a new appearing Fe 3d small Fermi surface pocket [14,15] gives a particular inhomogeneity giving nanoscale phase separation like in cuprates [15][16][17][18][19] which has been investigated by XANES [20][21][22] and predicted for Lifshitz transition in multiband Hubbard model [23,24]. From the application point of view, it is very important to explore this complex disorder controlled by space layers in the superconducting properties, such as the flux-pinning as it was made recently in cuprates [25].…”