Materials exhibiting a giant magnetocaloric effect (GMCE) need to be finely tuned with respect to their magnetic and structural properties, specifically their respective transition temperatures. Co-Mn-Ge and Co-Mn-Ge-Si thin-film materials libraries (MLs) were fabricated and characterized to determine the composition range in which the CoMnGe phase is stable and analyze selected single-phase measurement regions. Phase analysis was performed on these MLs and refined in regard to the CoMnGe single-phase region by synchrotron diffraction experiments. A comparison of the MLs revealed that the CoMnGe (HT) single-phase region gets smaller with the addition of Si and exists for 26.5 at. % < Co < 29.5 at. %, 34 at. % < Mn < 37 at. %, Ge ∼ 35 at. %, and Si ∼ 1.5 at. % in the quaternary ML. The investigation of magnetic and structural transition properties in this region revealed hard-magnetic behavior with Curie temperatures (Tc) between 261 and 274 K and large hysteresis widths with values >100 K for the structural transition. A low Co content was necessary to achieve an overlap of Tc and structural transition temperatures, leading to the most favorable properties for a GMCE to be found in Co26.5Mn37Ge35Si1.5.

中文翻译：

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Si替代对Co-Mn-Ge-Si薄膜材料库中CoMnGe相的存在，结构和磁性的影响。

表现出巨大的磁热效应（GMCE）的材料需要对其磁性和结构特性，特别是其各自的转变温度进行微调。制作并表征了Co-Mn-Ge和Co-Mn-Ge-Si薄膜材料库（MLs），以确定CoMnGe相稳定的组成范围，并分析了选定的单相测量区域。对这些ML进行了相分析，并通过同步加速器衍射实验对CoMnGe单相区进行了改进。MLs的比较显示，添加Si时，CoMnGe（HT）单相区域变小，并且存在26.5 at。％<Co <29.5 at。％，在34。％<Mn <37 at。％，Ge〜35 at。％，Si〜1.5at。％。在四元ML中的％。对这一区域的磁性和结构转变特性的研究表明，居里温度（Tc）在261和274 K之间，并且结构转变的值> 100 K时具有较大的磁滞宽度，具有硬磁行为。为了实现Tc和结构转变温度的重叠，需要低的Co含量，从而导致在Co26.5Mn37Ge35Si1.5中发现GMCE最有利的性能。