Probing CoFeNi thin films using polarised neutrons

Near-equimolar multi-component alloys, known as high entropy alloys (HEAs), possess potential for the development of new functional micromaterials. HEAs can be stabilised by their high number of alloying components (>4) to adopt the simple phases of pure elements rather than ordered intermetallic compounds. The phase stability may be tuned by careful alloy design, and the strategic selection of elements with the right chemical properties can lead to new combinations of structural and functional properties, which are highly desirable for magnetic thin-films. We have studied the possible elements in their tertiary form, including CoFeCr and CoFeNi thin films, to understand their basic magnetic behaviour before adding more elements to the alloys. The CoFeNi films showed unusual magnetic behaviour with thickness, and we would like to investigate this further using polarised neutrons.

近等摩尔多组元合金，即高熵合金（high entropy alloys, HEAs），具备开发新型功能性微材料的潜力。高熵合金可凭借其合金组元数目超过4种实现稳定，倾向于形成纯元素的简单相而非有序金属间化合物。可通过精细的合金设计调控相稳定性，而精准选择具备合适化学特性的元素，可获得结构与功能特性的新型组合，这对于磁性薄膜而言极具应用价值。在向合金中添加更多组元前，我们先以三元形式研究了潜在合金元素，包括CoFeCr与CoFeNi薄膜，以理解其基本磁学行为。CoFeNi薄膜展现出随厚度变化的反常磁学行为，我们计划利用极化中子进一步开展相关研究。