Weak ferromagnetism induced by atomic disorder in Fe2TiSn

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