Impact of the out-of-plane conductivity on spin transport evaluation in a van der Waals material

TL;DR

This paper investigates how out-of-plane conductivity anisotropy affects the evaluation of spin transport properties in layered van der Waals materials, proposing a new model for accurate measurements.

Contribution

It introduces a theoretical model for anisotropic spin diffusion, improving the accuracy of spin transport parameter extraction in layered materials.

Findings

Isotropic assumptions overestimate out-of-plane spin diffusion length.

Anisotropic modeling yields more accurate spin Hall conductivity values.

The study enhances understanding of anisotropic spin transport in layered materials.

Abstract

Layered materials are promising candidates for spintronic applications due to their unique electronic structures and spin transport properties. However, the strong anisotropic conductivity inherent in these materials complicates the quantitative evaluation of spin Hall conductivity and spin diffusion length. In this work, we present a comprehensive study of spin transport in a transition metal dichalcogenide PtTe$_2$ by combining a three-dimensional finite element model with nonlocal spin valve structures. We developed a theoretical model that treats an anisotropic spin diffusion in the same way as the conventional isotropic model, enabling the extraction of spin diffusion lengths along both the in-plane and out-of-plane directions. Our analysis revealed that the conventional isotropic assumption tends to overestimate some values, particularly for the out-of-plane spin diffusion length and spin Hall conductivity. These findings provide new insight into anisotropic spin diffusion and spin-charge conversions in layered materials and emphasize the importance of accounting for anisotropic conductivity in the design of spintronic devices.