Nanoscale phase separation in the iron chalcogenide superconductor K0.8Fe1.6Se

Abstract

Advanced synchrotron radiation focusing down to a size of 300 nm has been used to visualize nanoscale phase separation in the K 0.8 Fe 1.6 Se 2 superconducting system using scanning nanofocus single-crystal X-ray diffraction. The results show an intrinsic phase separation in K 0.8 Fe 1.6 Se 2 single crystals at T< 520 K, revealing coexistence of i) a magnetic phase characterized by an expanded lattice with superstructures due to Fe vacancy ordering and ii) a non-magnetic phase with an in-plane compressed lattice. The spatial distribution of the two phases at 300 K shows a frustrated or arrested nature of the phase separation. The space-resolved imaging of the phase separation permitted us to provide a direct evidence of nanophase domains smaller than 300 nm and different micrometer-sized regions with percolating magnetic or nonmagnetic domains forming a multiscale complex network of the two phases.

Fermi surface reconstruction of superoxygenated La2CuO4superconductors with ordered oxygen interstitials

“…The dopant-rich puddles of ordered dopants have been clearly observed also in iron chalcogenide superconductors and it has been shown that the two structural units have a quite different electronic structure with a superconducting or a magnetic phase. [25][26][27] In the underdoped regime of cuprates a structural phase separation between a dopant-poor antiferromagnetic phase and a dopant-rich metallic phase with doping close to 1/8 is clearly observed in La 2 CuO 4+y for 0< y <0.055 28 and YBa 2 Cu 3 O 6+y . 29 In the optimum and high doping regime of cuprates recent high-resolution ARPES and STM experiments [30][31][32] show multiple electronic components with electronic phase separation at low temperature.…”

Effect of iron content and potassium substitution inA0.8Fe1.6Se2Zhang1, Liu2, He3 et al. 2012Phys. Rev. B174120View full textAdd to dashboardCite

“…Very recent NMR measurements have detected clear signals from a majority magnetic phase as well as a minority superconducting one. 19 The appearance of phase separation occurring at nanometer scales has been detected by Mössbauer, 20 X-ray, 21 and in-plane optical spectroscopy measurements. 22 Scanning Tunneling Microscopy (STM) has been used to image this nanoscopic phase separation directly in epitaxially grown films.…”

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

“…More specifically, for example, microbeams have been used for mapping weak diffuse scattering in the real space in Scanning micro X Ray Diffraction (SµXRD) measurements. 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].…”