Epitaxial growth of the Heusler alloy Co2Cr1-xFexAl

We report a method for the growth of single-phase epitaxial thin films of compounds from the family of Heusler alloys Co2Cr1−xFexAl. Elemental targets were dc magnetron sputtered in 1.5 mtorr Ar gas onto MgO substrates held at 500 °C at a total growth rate of ≈0.8 A/s. As the Fe content increases, the structural quality improves, the level of chemical ordering increases, and the slope of the resistivity versus temperature, dρ/dt, above 50 K changes from negative to positive. An extraordinary Hall resistivity exceeding 1×10−8 Ω m is observed in the Cr-containing alloys at low temperature and room temperature. Preliminary work on the incorporation of a single quaternary alloy into spin valves shows maximum giant magnetoresistances ranging from 4% at 15 K to 2% at room temperature.

我们报道了一种生长赫斯勒合金Co₂Cr₁₋ₓFeₓAl族化合物单相外延薄膜的方法。在1.5毫托的氩气环境中，将元素靶材通过直流磁控溅射的方式沉积到保持在500°C的氧化镁衬底上，总生长速率约为0.8埃/秒。随着铁含量的增加，结构质量提高，化学有序度增加，并且在50 K以上电阻率随温度的变化率dρ/dt从负变为正。在含铬合金中，在低温和室温下观察到超过1×10⁻⁸Ω·m的反常霍尔电阻率。将一种单一的四元合金掺入自旋阀的初步工作表明，最大巨磁电阻在15 K时为4%，在室温时为2%。