MnCoGe alloys are widely recognized as an important family of rare-earth-free magnetocaloric materials by engineering its magnetostructural coupling for giant entropy changes. However, its practicability for magnetic refrigeration is largely hindered by the large thermal hysteresis. In this work, we show that the co-doped MnCoGe compound, namely Mn0.95Cu0.03CoGe with 2 both mol% Mn vacancies and 3 mol% Cu-doping for Mn, displays a maximum entropy change of 29.0 J kg−1K−1 at 295 K under a magnetic field of 5 T, together with a relative cooling power as high as 314.5 J kg−1 and a record low thermal hysteresis of 16 K. The co-doping strategy in MnCoGe finely tunes the structural transition temperature within the range of Curie temperature window, leading to a strong magnetostructural coupling and giant magnetocaloric effect. Meanwhile, Mn-deficiency and Cu-doping considerably reduce the energy difference between martensitic and austenitic MnCoGe, rendering a minimal thermal hysteresis. Our co-doped MnCoGe alloys are robust candidates for near-room-temperature magnetic refrigeration.

中文翻译：

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MnCoGe 合金的合理设计，以提高磁热性能并降低热滞


MnCoGe 合金被广泛认为是无稀土磁热材料的重要家族，其磁结构耦合针对巨大的熵变化进行了工程设计。然而，其磁制冷的实用性在很大程度上受到大热滞后的阻碍。在这项工作中，我们表明共掺杂的 MnCoGe 化合物，即 Mn0.95Cu0.03CoGe，具有 2 个 mol% Mn 空位和 3 mol% Cu 掺杂的 Mn，在 5 T 的磁场下，在 295 K 下显示出 29.0 J kg-1K-1 的最大熵变，以及高达 314.5 J kg-1 的相对冷却功率和 16 K 的历史低热滞后。MnCoGe 中的共掺杂策略在居里温度窗口范围内微调结构转变温度，从而产生较强的磁结构耦合和巨大的磁热效应。同时，Mn缺乏和Cu掺杂大大降低了马氏体和奥氏体MnCoGe之间的能量差，从而产生了最小的热滞后。我们的共掺杂 MnCoGe 合金是近室温磁制冷的可靠候选者。