论文标题

石墨烯/MOTE2范德华异质结构中的非常规的电荷转换转换

Unconventional charge-to-spin conversions in graphene/MoTe2 van der Waals heterostructures

论文作者

Ontoso, Nerea, Safeer, C. K., Herling, Franz, Ingla-Aynés, Josep, Yang, Haozhe, Chi, Zhendong, Robredo, Iñigo, Vergniory, Maia G., de Juan, Fernando, Calvo, M. Reyes, Hueso, Luis E., Casanova, Fèlix

论文摘要

旋转电荷互转换(SCI)是从具有强旋轨耦合(SOC)材料开发自旋装置的中心现象。对于具有高晶体对称性的材料,唯一允许的SCI过程是旋转电流,电荷电流和自旋极化方向相互正交的过程。因此,设计标准的SCI实验是为了最大程度地提高具有常规互惠几何形状的SCI过程所产生的信号。但是,在低对称材料中,还允许某些非正交的SCI过程。由于标准的SCI实验仅限于仅在SOC材料中以一个方向流动的电流电流,因此某些允许的SCI构型仍未开发。在这项工作中,我们在基于石墨烯的侧向旋转阀和低对称性MOTE $ _2 $的基于石墨烯的侧向旋转阀中进行了彻底的SCI研究。由于两种材料之间的接触电阻非常低,我们可以使用标准配置检测SCI信号,在该配置中,沿MOTE $ _2 $施加电荷电流,以及最近引入(3D-电流)配置,其中电荷电流可以在异质结构内的三个方向上控制。结果,我们观察到了三个不同的SCI组件,一个正交和两个非正交分量,对低对称材料的SCI过程有了新的见解。在室温下获得的大型SCI信号,以及3D电流配置的多功能性,为下一代基于自旋的设备的设计提供了可行性和灵活性。

Spin-charge interconversion (SCI) is a central phenomenon to the development of spintronic devices from materials with strong spin-orbit coupling (SOC). In the case of materials with high crystal symmetry, the only allowed SCI processes are those where the spin current, charge current and spin polarization directions are orthogonal to each other. Consequently, standard SCI experiments are designed to maximize the signals arising from the SCI processes with conventional mutually orthogonal geometry. However, in low-symmetry materials, certain non-orthogonal SCI processes are also allowed. Since the standard SCI experiment is limited to charge current flowing only in one direction in the SOC material, certain allowed SCI configurations remain unexplored. In this work, we performed a thorough SCI study in a graphene-based lateral spin valve combined with low-symmetry MoTe$_2$. Due to a very low contact resistance between the two materials, we could detect SCI signals using both a standard configuration, where the charge current is applied along the MoTe$_2$, and a recently introduced (3D-current) configuration, where the charge current flow can be controlled in three directions within the heterostructure. As a result, we observed three different SCI components, one orthogonal and two non-orthogonal, giving new insight into the SCI processes in low-symmetry materials. The large SCI signals obtained at room temperature, along with the versatility of the 3D-current configuration, provide feasibility and flexibility to the design of the next generation of spin-based devices.

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