Glassy Magnetic Transitions and Accurate Estimation of Magnetocaloric Effect in Ni-Mn Heusler Alloys.,ACS Applied Materials & Interfaces

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Glassy Magnetic Transitions and Accurate Estimation of Magnetocaloric Effect in Ni-Mn Heusler Alloys.
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2020-09-02 , DOI: 10.1021/acsami.0c11308
Le Zhang ₁ , Ji Zhang ₁ , Kaili Li ₂ , Chao Zhou ₂ , Yin Yao ₃ , Thiam Teck Tan ₁ , Danyang Wang ₁ , Sen Yang ₂ , Sean Li ₁ , Michael A Carpenter ₄

Affiliation

In this work, the structural and magnetic transitions of Heusler alloy Ni₅₀Mn₃₄In₁₄Ga₂ have been carefully studied through measurements of heat flow and magnetization under DC and AC magnetic fields. This alloy undergoes the transition sequence of spin-glassy martensite (SPM) → ferromagnetic austenite (FA) → paramagnetic austenite at ∼225 and ∼305 K, respectively, during heating. Splitting of zero-field-cooling (ZFC)/field-cooling (FC) curves in martensite is caused by the slowdown dynamics of spin glass as evidenced by frequency dispersion and aging effects. The development of a spin-glass state is believed to be the result of strain relaxation and interaction of ferroelastic twin walls in the martensite. The magnetocaloric effect (MCE) at the SPM–FA transition was then measured using indirect, quasi-direct, and direct methods. The MCE magnitudes are controlled by the entropy changes associated with the first-order martensite transition and magnetic ordering of austenite under the magnetic field. The existence of a spin-glass state in martensite can also improve the reversibility of the magnetostructural transitions, which is beneficial for the improvement of the reversibility of associated MCE. These results provide an in-depth understanding of the transitions and magnetic properties of the Ni–Mn Heusler alloys and suggest that the MCE at the first-order magnetostructural transitions estimated solely using indirect methods may need some revision.

中文翻译：

Ni-Mn Heusler合金的玻璃态磁跃迁和磁热效应的准确估计。

在这项工作中，赫斯勒合金Ni ₅₀ Mn ₃₄ In ₁₄ Ga ₂的结构和磁转变通过测量直流和交流磁场下的热流和磁化强度，已经对它们进行了仔细的研究。在加热期间，该合金分别在〜225和〜305 K处经历自旋玻璃状马氏体（SPM）→铁磁性奥氏体（FA）→顺磁性奥氏体的转变序列。马氏体中零场冷却（ZFC）/场冷却（FC）曲线的分裂是由自旋玻璃的减慢动力学引起的，如频散和时效效应所证明。据信自旋玻璃态的发展是马氏体中应变松弛和铁弹性双壁相互作用的结果。然后使用间接，准直接和直接方法测量了SPM–FA转变时的磁热效应（MCE）。MCE的大小受与一阶马氏体转变和磁场下奥氏体的磁有序性有关的熵变控制。马氏体中自旋玻璃态的存在还可以改善磁结构转变的可逆性，这有利于改善相关MCE的可逆性。这些结果提供了对Ni-Mn Heusler合金的转变和磁性的深入了解，并建议仅使用间接方法估算的一阶磁结构转变处的MCE可能需要进行一些修改。这有利于改善相关MCE的可逆性。这些结果提供了对Ni-Mn Heusler合金的转变和磁性的深入了解，并建议仅使用间接方法估算的一阶磁结构转变处的MCE可能需要进行一些修改。这有利于改善相关MCE的可逆性。这些结果提供了对Ni-Mn Heusler合金的转变和磁性的深入了解，并建议仅使用间接方法估算的一阶磁结构转变处的MCE可能需要进行一些修改。

更新日期：2020-09-30

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