A theoretical investigation of electronic and magnetic properties has been performed on the new members of Heusler alloys M2NiZ (M = Sc, Ti, and V; Z = Tl and Pb) that crystallize in an inverse Heusler XA structure. The overall electronic properties and magnetic moments are predominated by M atoms, where the total magnetic moment varies linearly with the number of valence electrons, following the Slater–Pauling rule with ferro- or ferri-magnetic ground states. Their Curie temperatures are well above the room temperature and are comparable to analogous compounds. Among the sample alloys, Sc2NiTl, Ti2NiTl, and Ti2NiPb are half-metals, whereas V2NiTl has a nearly half-metallic profile that can be tuned into novel half-metal under uniform strain. Their thermodynamic, mechanical, and dynamical stabilities are also verified from their formation energy, elastic constants, and phonon spectra, respectively. A strong correlation between the directional elastic sound velocities and spatial dependence of elastic moduli is also observed. The evaluated Poisson's ratio from elastic constants and charge density plots predicts the partial ionic nature of Ti2NiTl and Ti2NiPb and the covalent nature of Sc2NiTl and V2NiTl. The optical phonon modes are found to be both Raman and infrared active, whereas the reststrahlen band is observed in the far-infrared region.

中文翻译：

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新型 M2NiZ（M = Sc、Ti 和 V；Z = Tl 和 Pb）Heusler 合金的机械稳定性和半金属性起源

对以逆 Heusler XA 结构结晶的 Heusler 合金 M2NiZ（M = Sc、Ti 和 V；Z = Tl 和 Pb）的新成员进行了电子和磁性能的理论研究。整体电子性质和磁矩由 M 原子主导，其中总磁矩随价电子的数量线性变化，遵循铁磁性或亚铁磁性基态的 Slater-Pauling 规则。它们的居里温度远高于室温，可与类似化合物相媲美。在样品合金中，Sc2NiTl、Ti2NiTl 和 Ti2NiPb 是半金属，而 V2NiTl 具有接近半金属的轮廓，可以在均匀应变下调整为新型半金属。它们的热力学、机械和动力学稳定性也从它们的形成能中得到验证，分别为弹性常数和声子谱。还观察到定向弹性声速和弹性模量的空间依赖性之间的强相关性。根据弹性常数和电荷密度图评估的泊松比预测 Ti2NiTl 和 Ti2NiPb 的部分离子性质以及 Sc2NiTl 和 V2NiTl 的共价性质。发现光学声子模式同时具有拉曼和红外活性，而在远红外区域观察到剩余光谱带。来自弹性常数和电荷密度图的 s 比率预测 Ti2NiTl 和 Ti2NiPb 的部分离子性质以及 Sc2NiTl 和 V2NiTl 的共价性质。发现光学声子模式同时具有拉曼和红外活性，而在远红外区域观察到剩余光谱带。来自弹性常数和电荷密度图的 s 比率预测 Ti2NiTl 和 Ti2NiPb 的部分离子性质以及 Sc2NiTl 和 V2NiTl 的共价性质。发现光学声子模式同时具有拉曼和红外活性，而在远红外区域观察到剩余光谱带。