Co2MnGe ferromagnetic Heusler alloys: magnetic characteristics and hysteretic behavior by mean field theory

IF 1.7 4区物理与天体物理 Q3 PHYSICS, CONDENSED MATTER

The European Physical Journal B Pub Date : 2025-09-22 DOI:10.1140/epjb/s10051-025-01047-5

A. Elhani, A. Lafhal, T. Mouhrach, E. B. Choubabi, M. El Bouziani

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Abstract

In this study, we have successfully explored the magnetic properties and hysteresis behavior of the Heusler compound Co₂MnGe. To this end, the material was modeled as a mixed-spin ferromagnetic Ising system (5/2, 2) and the analysis was conducted using the mean-field approximation, based on the Gibbs-Bogoliubov inequality applied to the free energy. We examined the effect of various physical parameters, including exchange interactions, crystalline anisotropies, external magnetic field and temperature on the overall magnetic and hysteretic behavior of the system. The theoretical model highlighted the existence of both first- and second-order phase transitions, as well as the high sensitivity of hysteresis loops to variations in these parameters. Remarkable phenomena were also observed, such as the multiplicity of saturation values for ground-state magnetization and the formation of complex hysteresis loops. Finally, the results obtained are broadly in line with those reported in the literature, attesting to the relevance of this approach to the analysis of the magnetic properties of Heusler alloys.

Graphical abstract

The structure of Co₂MnGe, often known as the L2₁ structure, is a member of space group 225 (Fm⁻3m)

Abstract Image

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Co2MnGe铁磁Heusler合金：磁特性和磁滞特性的平均场理论

在这项研究中，我们成功地探索了Heusler化合物Co₂MnGe的磁性和磁滞行为。为此，将材料建模为混合自旋铁磁Ising系统（5/ 2,2），并基于Gibbs-Bogoliubov不等式应用于自由能，使用平均场近似进行分析。我们研究了各种物理参数，包括交换相互作用、晶体各向异性、外磁场和温度对系统整体磁滞行为的影响。该理论模型强调了一阶和二阶相变的存在，以及滞回回路对这些参数变化的高灵敏度。还观察到一些显著现象，如基态磁化饱和值的多重性和复杂磁滞回线的形成。最后，得到的结果与文献报道的结果大致一致，证明了这种方法与Heusler合金磁性分析的相关性。Co2MnGe的结构通常被称为L21结构，它是空间群225 （Fm−3m）中的一员。

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