Magnetoresistance in point contacts of the Heusler alloy Co2Cr0.6Fe0.4Al

Following a recent report predicting half-metallicity of Co2Cr0.6Fe0.4Al, we have examined point contacts of this material. Large magnetoresistances (up to 80%) have been observed at room temperature in small fields (10 mT). Magnetostriction in these fields is negligible. A spin polarisation of 81% is inferred. Mössbauer spectra show that 90% of the iron is ordered. The magnetisation of the alloy is 3.65μB per formula unit, and its Curie temperature is 665 K.