Abstract To probe the magnetic as well as thermoelectric performance of spinels with composition ZnMn2X4 (X = S, Se, Te), their structural, elastic, electronic and thermoelectric properties have been studied in the present work. Structural properties reveal stability of ferromagnetic (FM) phase in these spinels which is further confirmed by computing the heat of formation for these compounds. The mechanical properties of the ZnMn2X4 spinels have been investigated by computing their elastic constants, which show that all these spinels exhibit a brittle character. Moreover, electronic band structure and density of states reveal a half-metallic FM structure in all these spinels. Analysis of the band structure of these materials reveals a semiconducting nature in the spin down channel. Exchange constants (N0α and N0β) have been computed to directly probe the state splitting and our results large splitting of Mn 3d-states by N0β owing to its larger negative value as compared to N0α. The strong p-d hybridization is found to make exchange field dominant to crystal field which consequently induces ferromagnetism. In addition, the p-d hybridization reduces the magnetic moment of Mn ions by inducing traces of magnetic moments at non-magnetic sites. The observation of thermoelectric behavior within temperature range 200K–800K reveals positive Seeback coefficient indicating holes as majority charge carriers. Although the power factor is found to increase on going from ZnMn2S4 to ZnMn2Te4, our results clearly show improvement of power factor with increasing temperature.

中文翻译：

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锌基硫族化物 ZnMn2X4（X = S、Se、Te）作为有前景的自旋电子和热电材料：Ab-initio DFT 研究

摘要 为了探究成分为 ZnMn2X4 (X = S, Se, Te) 的尖晶石的磁和热电性能，本文研究了它们的结构、弹性、电子和热电性能。结构特性揭示了这些尖晶石中铁磁 (FM) 相的稳定性，通过计算这些化合物的形成热进一步证实了这一点。ZnMn2X4 尖晶石的机械性能已经通过计算它们的弹性常数进行了研究，这表明所有这些尖晶石都表现出脆性。此外，电子能带结构和态密度揭示了所有这些尖晶石中的半金属调频结构。对这些材料的能带结构的分析揭示了自旋向下通道中的半导体性质。已经计算了交换常数（N0α 和 N0β）以直接探测状态分裂，我们的结果由于 N0β 与 N0α 相比具有更大的负值，所以 N0β 对 Mn 3d 态的大量分裂。发现强 pd 杂化使交换场占晶体场的主导地位，从而诱导铁磁性。此外，pd 杂化通过在非磁性位置诱导磁矩痕迹来降低 Mn 离子的磁矩。在 200K-800K 温度范围内观察到的热电行为揭示了正 Seeback 系数，表明空穴是多数电荷载流子。尽管发现功率因数随着从 ZnMn2S4 到 ZnMn2Te4 的增加而增加，但我们的结果清楚地表明功率因数随着温度的升高而提高。