Half-Metallic Transport and Spin-Polarized Tunneling through the van der Waals Ferromagnet Fe<sub>4</sub>GeTe<sub>2</sub>
Anita Halder, Declan Nell, Antik Sihi, Akash Bajaj, Stefano Sanvito, Andrea Droghetti
Abstract
High Resolution Image Download MS PowerPoint Slide We examine the coherent spin-dependent transport properties of the van der Waals (vdW) ferromagnet Fe 4 GeTe 2 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 Fe 4 GeTe 2 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 Fe 4 GeTe 2 layers in the junction.