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Theoretical and Experimental Insights into the Effects of Zn Doping on the Magnetic and Magnetocaloric Properties of MnCoGe
Chemistry of Materials ( IF 7.2 ) Pub Date : 2020-07-10 , DOI: 10.1021/acs.chemmater.0c02294
YiXu Wang 1, 2 , Vincent Yannello 2 , Jacnel Graterol 2 , Hu Zhang 1 , Yi Long 1 , Michael Shatruk 2, 3
Affiliation  

MnCoGe-based materials have the potential to exhibit giant magnetocaloric effects due to the coupling between magnetic ordering and a martensitic phase transition. Such coupling can be realized by matching the temperatures of the magnetic and structural phase transitions. To understand the site preference of different elements and the effect of hole or electron doping on the stability of different polymorphs of MnCoGe, crystal orbital Hamilton population (COHP) analysis has been employed for the first time to evaluate peculiarities of chemical bonding in this material. The shortest Mn–Mn bond in the structure is found to be pivotal to the observed ferromagnetic behavior and structural stability of hexagonal MnCoGe. Based on this insight, eliminating antibonding features of the shortest Mn–Mn bond at the Fermi energy is proposed as a feasible way to stabilize the hexagonal polymorph, which is then realized experimentally by substitution of Zn for Ge. The hexagonal MnCoGe structure is stabilized due to depopulation of the antibonding states and strengthening of the Mn–Mn bonding. This change in chemical bonding leads to anisotropic evolution of lattice parameters. The structural and magnetic properties of Zn-doped MnCoGe have been elucidated by synchrotron X-ray diffraction and magnetic measurements, respectively.

中文翻译:

锌掺杂对MnCoGe的磁磁热性质影响的理论和实验研究

MnCoGe基材料由于磁有序与马氏体相变之间的耦合而具有显示出巨大的磁热效应的潜力。这种耦合可以通过匹配磁性和结构相变的温度来实现。为了了解不同元素的位置偏好以及空穴或电子掺杂对MnCoGe不同多晶型物稳定性的影响,首次使用了晶体轨道汉密尔顿人口(COHP)分析来评估这种材料中化学键的特性。发现结构中最短的Mn-Mn键对于六角形MnCoGe的铁磁行为和结构稳定性至关重要。基于这种见识,提出消除在费米能量下最短Mn-Mn键的反键特征是稳定六边形多晶型物的可行方法,然后通过用Zn代替Ge进行实验来实现。六角形MnCoGe结构由于反键态的减少和Mn-Mn键的增强而得以稳定。化学键的这种变化导致晶格参数的各向异性演变。Zn掺杂的MnCoGe的结构和磁性分别通过同步加速器X射线衍射和磁性测量得到了阐明。化学键的这种变化导致晶格参数的各向异性演变。Zn掺杂的MnCoGe的结构和磁性分别通过同步加速器X射线衍射和磁性测量得到了阐明。化学键的这种变化导致晶格参数的各向异性演变。Zn掺杂的MnCoGe的结构和磁性分别通过同步加速器X射线衍射和磁性测量得到了阐明。
更新日期:2020-08-11
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