title: Electronic phase separation in the slightly underdoped iron pnictide superconductor Ba1-xKxFe2As2.
abstract: Here we present a combined study of the slightly underdoped novel pnictide superconductor Ba1-xKxFe2As2 by means of x-ray powder diffraction, neutron scattering, muon-spin rotation (microSR), and magnetic force microscopy (MFM). Static antiferromagnetic order sets in below T{m} approximately 70 K as inferred from the neutron scattering and zero-field-microSR data. Transverse-field microSR below Tc shows a coexistence of magnetically ordered and nonmagnetic states, which is also confirmed by MFM imaging. We explain such coexistence by electronic phase separation into antiferromagnetic and superconducting- or normal-state regions on a lateral scale of several tens of nanometers. Our findings indicate that such mesoscopic phase separation can be considered an intrinsic property of some iron pnictide superconductors.
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany.
authors.forename: J T
authors.initials: JT
authors.lastname: Park
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authors.lastname: Niedermayer
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authors.initials: GL
authors.lastname: Sun
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authors.lastname: Schulz
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authors.lastname: Shapoval
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authors.lastname: Wolff
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authors.lastname: Yang
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authors.lastname: Lin
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authors.lastname: Keimer
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authors.lastname: Hinkov