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Theoretical Study of Spintronics Devices Based on Two-Dimensional Materials

基于二维材料的自旋电子器件理论研究

基本信息

批准号：
20J22909
负责人：
Wicaksono Yusuf
金额：
$ 1.6万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for JSPS Fellows
财政年份：
2020
资助国家：
日本
起止时间：
2020-04-24 至 2023-03-31
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-20J22909/
关键词：
graphene (Gr)Interface spin-flipping spin-rotation spin-orbit coupling Gr-hBN heterostructure Dirac cone engineering spin-mechatronic proximity effect magnetoresistance (MR)ultimate MR ratio hBN-Gr-hBN MTJ new MTJ mechanism

项目摘要

A first-principles study was done to look at the effect of spin-orbit coupling (SOC) on the interface between graphene (Gr) and nickel (Ni). Due to SOC, when Ni atoms were far from the interface, they were magnetized in a parallel direction to the interface. As they move toward the interface, they begin to rotate in a direction perpendicular to the interface until they have full perpendicular magnetization at the interface. This rotation is caused by the fact that hybridization with Gr reduces the in-plane orbital moment and makes the out-of-plane orbital moment stronger at the interface. This result was also applied to the hexagonal Boron Nitride (hBN)/Ni interface. Further, it was confirmed that this effect does not affect the controllable Dirac cone of graphene in the proposed Ni/Gr/Ni as well as Ni/hBN-Gr-hBN/Ni device, showing the effectiveness of controlling in-plane spin-current on Gr for the spin-valve device.Parallelly, we found a spin-flipping mechanism that can be initiated on the induced magnetic moment of C atoms in Gr/Ni when it hybridizes with a metal atom of the metal complex and a mechanical disturbance is made to the metal complex. This spin-flipping happens because the density of states of C atoms in the spin-majority channel near Fermi energy moves from energy levels below Fermi energy to energy levels above Fermi energy due to changes in the strength of the bonds, reducing the electron population in the spin-majority channel. This mechanism can be used for local control of the graphene Dirac cone, fine-tuning the in-plane conductance of graphene.

进行第一性原理研究以观察自旋轨道耦合（SOC）对石墨烯（Gr）和镍（Ni）之间的界面的影响。由于SOC的存在，当Ni原子远离界面时，它们沿平行于界面的方向被磁化。当它们向界面移动时，它们开始在垂直于界面的方向上旋转，直到它们在界面处具有完全垂直的磁化。这种旋转是由于与Gr的杂化降低了面内轨道矩，并使界面处的面外轨道矩更强。该结果也适用于六方氮化硼（hBN）/Ni界面。此外，证实了这种效应不影响所提出的Ni/Gr/Ni以及Ni/hBN-Gr-hBN/Ni器件中石墨烯的可控狄拉克锥，这表明对于自旋阀器件控制Gr上的面内自旋电流的有效性。我们发现了一种自旋翻转机制，它可以在Gr/当Ni与金属络合物的金属原子杂交并且对金属络合物进行机械扰动时，这种自旋翻转的发生是因为在费米能附近的自旋多数通道中的C原子的态密度由于键强度的变化而从费米能以下的能级移动到费米能以上的能级，从而减少了自旋多数通道中的电子布居。该机制可用于石墨烯狄拉克锥的局部控制，微调石墨烯的面内电导。