  The disordered antiferromagnet \pfn (\pfns) is investigated in a wide
temperature range by combining M\"ossbauer spectroscopy and neutron diffraction
experiments. It is demonstrated that the magnetic ground state is a {\it
microscopic} coexistence of antiferromagnetic and a spin-glass orders. This
speromagnet-like phase features frozen-in short-range fluctuations of the
Fe$^{3+}$ magnetic moments that are transverse to the long-range ordered
antiferromagnetic spin component.
