Current-perpendicular-to-plane transport properties of 2D ferromagnetic material CrTe₂

Heterostructures of van der Waals (vdW) ferromagnetic materials have become a focal point in research of low-dimensional spintronic devices. The current direction in spin valves is commonly perpendicular to the plane (CPP). However, the transport properties of the CPP mode remain largely unexplored. In this work, current-in-plane (CIP) mode and CPP mode for CrTe₂ thin films are carefully studied. The temperature-dependent longitudinal resistance transitions from metallic (CIP) to semiconductor behavior (CPP), with the electrical resistivity of CPP increased by five orders of magnitude. More importantly, the transport properties of the CPP can be categorized into a single-gap tunneling-through model with the activation energy (E_a) of ∼ 1.34 meV/gap at 300–150 K, the variable range hopping model with a linear negative magnetoresistance at 150–20 K, and weak localization region with a nonlinear magnetic resistance below 20 K. This study explores the vertical transport in CrTe₂ materials for the first time, contributing to understand its unique properties and to pave the way for its potential in spin valve devices.