Abstract In the present work, we reveal a novel finding, that is, self-assembled grain boundary precipitates for realizing the magnetic-field-induced metamagnetic transition by employing low melting point metal in materials. This strategy has been experimentally verified in a well-established ferrimagnetic compound Mn2Sb by doping the bismuth (Bi) element with a low melting point of just 271.3°C. Bi solidifies later than the Mn2(Sb,Bi) main phase in (Mn2Sb)1-xBix system (the melting point of ~948°C for Mn2Sb), and aggregates spontaneously along the grain boundaries, forming Bi-rich grain boundary precipitates to coat main phase grains. This is very similar to the Nd-rich grain boundary phase in Nd-Fe-B permanent magnets. The fraction of Bi-rich grain boundary phase can be controlled by Bi-content. As a result, the magnetic field induced steep magnetoelastic transition from antiferromagnetic to ferrimagnetic is achieved in (Mn2Sb)0.89Bi0.11 alloy with giant multiple functional properties in Bi-doped Mn2Sb. Especially, the magnetic entropy change maximum nearly quadruples when Bi-doping increases from 0.03 to 0.11. Giant negative magnetoresistance of more than 65% under μ0∆H = 0–5 T, and magnetostrain of ~1802 ppm under μ0H = 8.5 T are obtained in (Mn2Sb)0.89Bi0.11. It should pave a way to achieve the magnetic transition and enhance the magnetoresponsive effects in designing similar coherent materials by employing low melting point metal doping to form the dual-phase heterogeneous structure.

中文翻译：

---

自组织富铋晶界析出物在Bi掺杂Mn2Sb中实现陡峭的磁场驱动变磁转变

摘要 在目前的工作中，我们揭示了一个新发现，即通过在材料中使用低熔点金属来实现磁场诱导的变磁转变的自组装晶界沉淀物。通过掺杂具有仅 271.3°C 的低熔点的铋 (Bi) 元素，该策略已在成熟的亚铁磁性化合物 Mn2Sb 中得到了实验验证。Bi 在 (Mn2Sb)1-xBix 体系（Mn2Sb 的熔点约为 948°C）中的 Mn2(Sb,Bi) 主相之后凝固，并沿晶界自发聚集，形成富 Bi 晶界沉淀物以涂覆主相晶粒。这与 Nd-Fe-B 永磁体中富含 Nd 的晶界相非常相似。富铋晶界相的比例可以通过铋含量来控制。因此，在 (Mn2Sb)0.89Bi0.11 合金中实现了磁场诱导的从反铁磁性到亚铁磁性的陡峭磁弹性转变，在 Bi 掺杂的 Mn2Sb 中具有巨大的多功能特性。特别是，当 Bi 掺杂从 0.03 增加到 0.11 时，磁熵变化最大值接近四倍。在 (Mn2Sb)0.89Bi0.11 中获得了在 μ0ΔH = 0-5 T 下超过 65% 的巨大负磁阻和在 μ0H = 8.5 T 下~1802 ppm 的磁应变。通过采用低熔点金属掺杂形成双相异质结构，应该为设计类似相干材料的磁跃迁和增强磁响应效应铺平道路。特别是，当 Bi 掺杂从 0.03 增加到 0.11 时，磁熵变化最大值接近四倍。在 (Mn2Sb)0.89Bi0.11 中获得了在 μ0ΔH = 0-5 T 下超过 65% 的巨大负磁阻和在 μ0H = 8.5 T 下~1802 ppm 的磁应变。通过采用低熔点金属掺杂形成双相异质结构，应该为设计类似相干材料的磁跃迁和增强磁响应效应铺平道路。特别是，当 Bi 掺杂从 0.03 增加到 0.11 时，磁熵变化最大值接近四倍。在 (Mn2Sb)0.89Bi0.11 中获得了在 μ0ΔH = 0-5 T 下超过 65% 的巨大负磁阻和在 μ0H = 8.5 T 下~1802 ppm 的磁应变。通过采用低熔点金属掺杂形成双相异质结构，应该为设计类似相干材料的磁跃迁和增强磁响应效应铺平道路。