Abstract
Here we present a combined study of the slightly underdoped novel pnictide superconductor by means of x-ray powder diffraction, neutron scattering, muon-spin rotation (), and magnetic force microscopy (MFM). Static antiferromagnetic order sets in below as inferred from the neutron scattering and zero-field- data. Transverse-field below 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.
- Received 14 November 2008
DOI:https://doi.org/10.1103/PhysRevLett.102.117006
©2009 American Physical Society