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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.

进行了第一性原理研究，以观察自旋轨道耦合 (SOC) 对石墨烯 (Gr) 和镍 (Ni) 之间界面的影响。由于 SOC，当 Ni 原子远离界面时，它们会沿与界面平行的方向被磁化。当它们移向界面时，它们开始沿垂直于界面的方向旋转，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而引起的。该结果也适用于六方氮化硼（hBN）/Ni 界面。此外，还证实这种效应不会影响所提出的 Ni/Gr/Ni 以及 Ni/hBN-Gr-hBN/Ni 器件中石墨烯的可控狄拉克锥，显示了自旋阀器件控制 Gr 上面内自旋电流的有效性。同时，我们发现了一种自旋翻转机制，当 Gr/Ni 中的 C 原子与金属络合物的金属原子并对金属络合物进行机械扰动。发生这种自旋翻转的原因是，由于键强度的变化，费米能附近的自旋多数通道中的 C 原子的态密度从费米能量以下的能级移动到费米能量以上的能级，从而减少了自旋多数通道中的电子数量。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。