Weak ferromagnetism induced by atomic disorder in Fe2TiSn

Electrical resistivity, magnetization, and specific-heat measurements on th e Heusler-type alloy Fe2TiSn reveal the occurrence of weak ferromagnetism b elow 240 K and heavy fermion behavior with a quasiparticle effective mass o f similar to 40 times the free electron mass. Ah initio electronic structur e calculations, which are in good agreement with measured x-ray photoemissi on valence-band spectra, yield a nonmagnetic ground state with a pseudogap located at the Fermi level. Atomic disorder inferred from Rietveld refineme nt of powder x-ray-diffraction data and its effect on the calculated electr onic structure suggest that the weak ferromagnetism and the heavy fermion b ehavior may be induced by atomic disorder in Fe2TiSn and other Heusler allo ys as well.