Zhang Qiaoxuan, Wang Cong, Wang Wenjie, Sun Rong, Zheng Rongjie, Ji Qingchang, Yan Hongwei, Wang Zhengbo, He Xin, Wang Hongyan, Yang Chang, Yu Jinchen, Zhang Lingjiang, Lei Ming, Wang Zhongchang
Department of Electrical Engineering and Automation, Hebei University of Water Resources and Electric Engineering, Cangzhou 061001, China.
Joint Training Program, Chongqing University of Posts and Telecommunications and Guidance Environmental Emergency Technical Equipment Research Center (Chongqing) Co., Ltd., Chongqing 400065, China.
Nanomaterials (Basel). 2025 Aug 14;15(16):1246. doi: 10.3390/nano15161246.
Magnetic tunnel junctions (MTJs) are pivotal for spintronic applications such as magneto resistive memory and sensors. Two-dimensional van der Waals heterostructures offer a promising platform for miniaturizing MTJs while enabling the twist-angle engineering of their properties. Here, we investigate the impact of twisting the insulating barrier layer on the performance of a van der Waals MTJ with the structure graphene/1T-VSe/h-BN/1T-VSe/graphene, where 1T-VSe serves as the ferromagnetic electrodes and the monolayer h-BN acts as the tunnel barrier. Using first-principles calculations based on density functional theory (DFT) combined with the non-equilibrium Green's function (NEGF) formalism, we systematically calculate the spin-dependent transport properties for 18 distinct rotational alignments of the h-BN layer (0° to 172.4°). Our results reveal that the tunneling magnetoresistance (TMR) ratio exhibits dramatic, rotation-dependent variations, ranging from 2328% to 24,608%. The maximum TMR occurs near 52.4°. An analysis shows that the twist angle modifies the d-orbital electronic states of interfacial V atoms in the 1T-VSe layers and alters the spin polarization at the Fermi level, thereby governing the spin-dependent transmission through the barrier. This demonstrates that rotational manipulation of the h-BN layer provides an effective means to engineer the TMR and performance of van der Waals MTJs.
磁隧道结（MTJs）对于诸如磁阻存储器和传感器等自旋电子学应用至关重要。二维范德华异质结构为MTJs的小型化提供了一个有前景的平台，同时能够对其性能进行扭转角工程调控。在此，我们研究了对具有石墨烯/1T-VSe/h-BN/1T-VSe/石墨烯结构的范德华MTJ的绝缘势垒层进行扭转对其性能的影响，其中1T-VSe用作铁磁电极，单层h-BN用作隧道势垒。使用基于密度泛函理论（DFT）结合非平衡格林函数（NEGF）形式的第一性原理计算，我们系统地计算了h-BN层18种不同旋转取向（0°至172.4°）的自旋相关输运性质。我们的结果表明，隧道磁电阻（TMR）比率呈现出显著的、与旋转相关的变化，范围从2328%到24608%。最大TMR出现在52.4°附近。分析表明，扭转角改变了1T-VSe层中界面V原子的d轨道电子态，并改变了费米能级处的自旋极化，从而控制了通过势垒的自旋相关传输。这表明对h-BN层的旋转操纵为设计范德华MTJs的TMR和性能提供了一种有效手段。
