Large tunneling magnetoresistance at room temperature using a Heusler alloy with the B2 structure

A Co2Cr0.6Fe0.4Al Heusler alloy film exhibited a B2 structure, which,was deposited using a magnetron sputtering system on a, thermally oxidized Si substrate at room temperature without any buffer layers. The film exhibited the magnetic moment of 2.04mu(B) per formula unit, nearly the integer number of Bohr magnetons, suggesting a localized nature of ferromagnetisin similar to that of many Heusler compounds, which is a necessary condition for half metallicity. A spin- valve-type tunneling junction with a Co-2(Cr, Fe)Al Heusler alloy film was fabricated using metal masks, which consists Of Co2Cr0.6Fe0.4Al(10 nm)/AlOx (1.8 nm)/CoFe (3 nm)/NiFe (5 nm)/IrMn (15 nm)/Ta (5 nm), deposited on a thermally oxidized Si substrate without a buffer layer. The junction demonstrated large tunneling magnetoresistances of 16% at room temperature and 26.5% at 5K.

一种Co₂Cr₀.₆Fe₀.₄Al赫斯勒合金薄膜呈现出B2结构，它是在室温下利用磁控溅射系统在热氧化硅衬底上沉积而成，且没有任何缓冲层。该薄膜每个化学式单位的磁矩为2.04μB，几乎是玻尔磁子的整数倍，这表明其铁磁性具有局域性，与许多赫斯勒化合物类似，这是半金属性的必要条件。利用金属掩模制备了一种具有Co₂(Cr, Fe)Al赫斯勒合金薄膜的自旋阀型隧道结，其结构为Co₂Cr₀.₆Fe₀.₄Al（10纳米）/AlOx（1.8纳米）/CoFe（3纳米）/NiFe（5纳米）/IrMn（15纳米）/Ta（5纳米），沉积在无缓冲层的热氧化硅衬底上。该结在室温下表现出16%的大隧道磁电阻，在5K时为26.5%。