Robust half-metallicities and perfect spin transport properties in 2D transition metal dichlorides†,Journal of Materials Chemistry C

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Robust half-metallicities and perfect spin transport properties in 2D transition metal dichlorides†
Journal of Materials Chemistry C ( IF 5.7 ) Pub Date : 2018-03-14 00:00:00 , DOI: 10.1039/c8tc00443a
Yulin Feng _{1,

2,

3,

4} , Xuming Wu _{1,

2,

3,

4} , Jiangchao Han _{1,

2,

3,

4} , Guoying Gao _{1,

2,

3,

4,

5}

Affiliation

2D graphene-like materials have attracted growing interest due to their extraordinary electronic, optoelectronic and electrochemical properties. However, most pristine 2D graphene-like monolayers are found to be nonmagnetic, limiting their potential spintronic applications. Searching for 2D magnetic materials in pristine graphene-like monolayers is still a great challenge. In this work, inspired by the experimental layered transition metal dichlorides (TMDCs), MCl₂ (M = V, Cr, Mn, Fe, Co, Ni), we demonstrate from first-principles calculations that all the FeCl₂, CoCl₂ and NiCl₂ monolayers with 1T and 1H phases exhibit ferromagnetic orders. Half-metallicities with large half-metallic gaps (0.34–1.06 eV) are observed in 1H-VCl₂, CrCl₂, CoCl₂ and NiCl₂ monolayers as well as 1T-CrCl₂, FeCl₂ and CoCl₂ monolayers, and the half-metallicities are robust against biaxial strain up to 10% extension and 10% compression. Other MCl₂ monolayers are spin-polarized semiconductors. The different crystal fields between 1T and 1H phases and the different numbers of 3d electrons for different transition metals are responsible for the different magnetic and electronic behaviors of MCl₂ monolayers. More importantly, combining first-principles with the nonequilibrium Green's function, we for the first time reveal that the 1T-FeCl₂ monolayer exhibits an excellent spin filtering effect, a negative differential resistance effect and high magnetoresistance (up to 1.34 × 10⁵%), which are explained from the calculated spin-dependent band structure and spin-dependent transmission spectra. Similar phenomena are also found in other half-metallic MCl₂ monolayers. The robust half-metallicities, large half-metallic gaps and perfect spin transport properties suggest that MCl₂ monolayers are promising candidates for 2D spintronic applications.

中文翻译：

二维过渡金属二氯化物中的稳健半金属性和完美的自旋输运性质†

由于二维石墨烯类材料具有非凡的电子，光电和电化学性能，因此吸引了越来越多的兴趣。但是，发现大多数原始的2D石墨烯样单层都是非磁性的，从而限制了其潜在的自旋电子学应用。在原始石墨烯状单层中搜索2D磁性材料仍然是一个巨大的挑战。在这项工作中，受实验性层状过渡金属二氯化物（TMDC）MCl ₂（M = V，Cr，Mn，Fe，Co，Ni）的启发，我们从第一性原理计算证明了所有FeCl ₂，CoCl ₂和具有1T和1H相的NiCl ₂单层表现出铁磁有序。在1H-VCl中观察到具有大的半金属间隙（0.34–1.06 eV）的半金属_{如图2所示}，CrCl₂，CoCl₂和NiCl₂单层以及1T-CrCl₂，FeCl₂和CoCl₂单层，并且半金属抗双轴应变的能力强至10％延伸和10％压缩。其他MCl₂单层是自旋极化半导体。1T和1H相之间的不同晶体场和不同过渡金属的3d电子数量不同，是MCl₂单层磁性和电子行为不同的原因。更重要的是，结合第一性原理和非平衡格林函数，我们第一次揭示了1T-FeCl₂单层膜具有优异的自旋滤波效果，负差动电阻效应和高磁阻（高达1.34×10 ⁵％），这可从计算出的自旋相关能带结构和自旋相关透射光谱进行解释。在其他半金属MCl ₂单层中也发现了类似的现象。坚固的半金属性，大的半金属间隙和完美的自旋输运性能表明，MCl ₂单层是2D自旋电子学应用的有希望的候选者。

更新日期：2018-03-14

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