  Fe2Al5 contains a Fe-Al matrix through which are threaded disordered
one-dimensional chains of overlapping Al sites. We report magnetic,
nuclear-magnetic-resonance (NMR), and specific-heat measurements addressing its
magnetic and vibrational properties. The Curie-type susceptibility is found to
be due to dilute moments, likely due to wrong-site Fe atoms. 27Al NMR shift and
spin-lattice relaxation measurements confirm these to be indirectly coupled
through a Ruderman-Kittel-Kasuya-Yoshida-type interaction. Specific-heat
results indicate a large density of low-energy vibrational modes. These
excitations generate a linear-T contribution to the specific heat, which
however freezes out below about 10 K. These results are attributed to the
presence of anharmonic vibrational modes associated with the disordered
structural chains.
