Halder Anita, Nell Declan, Sihi Antik, Bajaj Akash, Sanvito Stefano, Droghetti Andrea
School of Physics and CRANN, Trinity College, Dublin 2, Ireland.
Department of Physics, SRM University - AP, Amaravati 522 502, Andhra Pradesh, India.
Nano Lett. 2024 Jul 31;24(30):9221-9228. doi: 10.1021/acs.nanolett.4c01479. Epub 2024 Jul 22.
We examine the coherent spin-dependent transport properties of the van der Waals (vdW) ferromagnet FeGeTe using density functional theory combined with the nonequilibrium Green's function method. Our findings reveal that the conductance perpendicular to the layers is half-metallic, meaning that it is almost entirely spin-polarized. This property persists from the bulk to a single layer, even under significant bias voltages and with spin-orbit coupling. Additionally, using dynamical mean field theory for quantum transport, we demonstrate that electron correlations are important for magnetic properties but minimally impact the conductance, preserving almost perfect spin-polarization. Motivated by these results, we then study the tunnel magnetoresistance (TMR) in a magnetic tunnel junction consisting of two FeGeTe layers with the vdW gap acting as an insulating barrier. We predict a TMR ratio of ∼500%, which can be further enhanced by increasing the number of FeGeTe layers in the junction.
我们使用密度泛函理论结合非平衡格林函数方法，研究了范德华（vdW）铁磁体FeGeTe的相干自旋相关输运性质。我们的研究结果表明，垂直于层的电导是半金属性的，这意味着它几乎完全是自旋极化的。即使在显著的偏置电压下且存在自旋轨道耦合时，这种性质从体材料到单层都持续存在。此外，通过将动态平均场理论用于量子输运，我们证明电子关联对磁性很重要，但对电导的影响极小，几乎保持完美的自旋极化。受这些结果的推动，我们接着研究了由两个FeGeTe层组成的磁性隧道结中的隧道磁电阻（TMR），其中vdW能隙充当绝缘势垒。我们预测TMR比率约为500%，通过增加结中FeGeTe层的数量可进一步提高该比率。
