Thermally-driven large current-perpendicular-to-plane magnetoresistance in ultrathin flakes of vanadium diselenide.

Current-perpendicular-to-plane magnetoresistance (CPP MR) in layered heterojunctions is at the heart of modern magnetic field sensing and data storage technologies. van der waals heterostructures and two-dimensional (2D) magnets opened a new playground for exploring this effect, although most 2D magnets exhibit large CPP MR only at very low temperatures due to their very low Curie temperatures. vanadium diselenide (VSe 2 ) is a promising material since its monolayers can potentially act as room temperature ferromagnets. VSe 2 multilayers have been predicted to exhibit CPP MR effects, although experimental work in this area remains scarce. In this work we investigate CPP MR in 1T-VSe 2 ultrathin flakes, revealing a large (∼60%-70%), positive, linear, and non saturating CPP MR, which persists close to room temperature (∼250 K), in a relatively small magnetic field range of ±12 kG . The CPP MR has been found to increase with decreasing flake thickness. The CPP MR originates due to the intrinsic inhomogeneity in the CPP transport path, and exhibits unprecedented immunity against thermal fluctuations, leading to increasingly enhanced MR as temperature is increased, even significantly beyond the charge density wave transition temperature . The observed 'thermally-driven' MR features are remarkably robust and reproducible, and can offer a viable route for developing practical room temperature 2D based magnetic sensor technologies. Our results also suggest that harnessing similar effects in other 2D systems could result in large MR as well, thereby motivating further research on CPP transport in these systems, which has been relatively unexplored so far.