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arXiv 2106.07960cond-mat.mtrl-sci
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少层1 T相CrTe2的厚度相关磁转变

Thickness Dependent Magnetic Transition in Few Layer 1T Phase CrTe2

Pengfei Gao, Xingxing Li, Jinlong Yang

摘要:

室温二维(2D)铁磁性在实际自旋电子学应用中是非常需要的。最近,已经成功地合成了具有五层和更厚层的1 T相CrTe 2(1 T-CrTe 2)纳米片,其都表现出铁磁(FM)金属的性质,居里温度在305 K左右。然而,当连续地将纳米片的厚度减小到单层极限时,其中的铁磁性是否可以保持仍然是未知的。通过第一性原理计算,我们研究了1 ~ 6层CrTe 2纳米片的磁性演化,发现了几个有趣的现象:第一,单层CrTe 2纳米片更倾向于锯齿形反铁磁(AFM)态,其能量远低于FM态.第二,在2 - 4层CrTe_2中,层内和层间磁耦合都是AFM。最后,当层数等于或大于5时,层内和层间磁耦合变为FM。理论分析表明,少层CrTe 2相对于体相的面内晶格收缩是产生层内AFM-FM磁转变的主要因素。同时,只要层内耦合达到FM,层间耦合将伴随着从AFM切换到FM。这种高度厚度依赖的磁性为控制2D材料的磁性提供了新的视角。

英文摘要:

Room temperature two-dimensional (2D) ferromagnetism is highly desired in practical spintronics applications. Recently, 1T phase CrTe2 (1T-CrTe2) nanosheets with five and thicker layers have been successfully synthesized, which all exhibit the properties of ferromagnetic (FM) metals with Curie temperatures around 305 K. However, whether the ferromagnetism therein can be maintained when continuously reducing the nanosheet's thickness to monolayer limit remains unknown. Here, through first-principles calculations, we explore the evolution of magnetic properties of 1 to 6 layers CrTe2 nanosheets and several interesting points are found: First, unexpectedly, monolayer CrTe2 prefers a zigzag antiferromagnetic (AFM) state with its energy much lower than that of FM state. Second, in 2 to 4 layers CrTe2, both the intralayer and interlayer magnetic coupling are AFM. Last, when the number of layers is equal to or greater than five, the intralayer and interlayer magnetic coupling become FM. Theoretical analysis reveals that the in-plane lattice contraction of few layer CrTe2 compared to bulk is the main factor producing intralayer AFM-FM magnetic transition. At the same time, as long as the intralayer coupling gets FM, the interlayer coupling will concomitantly switch from AFM to FM. Such highly thickness dependent magnetism provides a new perspective to control the magnetic properties of 2D materials.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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