Executive Summary : | In this era of artificial intelligence (AI), computational devices have become an indispensable part of our lives. In the past few years, the performance of microprocessors increased exponentially, but the memory and storage systems could not match that pace. Hence, there is an urgent need for low-power and high-speed nonvolatile memory devices. Magnetic random-access memory (MRAM) is a nonvolatile device that has these characteristics and thus can potentially be used as a memory and a storage device and therefore considered a universal memory solution. Presently, the spin-transfer torque (STT) technique is being used to manipulate magnetization in MRAM devices; however, it requires a large current density that creates a Joule heating effect and also reduces device endurance. A novel concept of spin-orbit torque (SOT) has recently shown a pathway to realize low-power operating MRAM devices. The magnetic manipulation in SOT-MRAM is accomplished by the charge current-induced spin current in a nonmagnetic layer. Such charge-spin conversion happens due to the Spin Hall Effect (SHE). The current required to realize the SOT effect is much less than the STT effect; therefore, the corresponding heating issue is less pronounced in SOT devices. Besides this, the reading and writing paths in three-terminal SOT devices are different, which increases the switching speed and device endurance. So, SOT-MRAM is quite more favorable than STT-MRAM in all device aspects. Several materials, such as Pt, Ta, W, alloys, topological insulators, etc., have been explored for efficient charge-spin conversation. Still, a material with high charge-spin conversion efficiency and high conductivity is yet to be demonstrated. Delafossite materials are promising candidates for energy-efficient SOT-MRAM applications. Because of the quasi 2D structure, these materials show extremely high conductivity and a very long mean free path. This project aims to investigate the spin-hall effect in thin-film delafossite materials grown by pulsed laser deposition for SOT-MRAM applications. The thin-film growth of delafessoite oxide film would require a detailed understanding of the growth kinetics to achieve the desired properties. For this, the structural, chemical, and morphological characterization will be performed. The novelty of the project lies in the attempt to converge two of the most recently debated areas in condensed matter physics, namely spin-orbit coupling and spin hall effect (SHE), to give rise to the spin-orbit torque (SOT) effect in delafossite material. Moreover, the role of SHE and interfacial Rashba-Edelstein effect in the generation of SOT, the spin-accumulation at the delafossite/ferromagnet interface, and corresponding spin-momentum locking effect, and finally, the spin diffusion into the ferromagnetic layer would be investigated. The ultimate goal of this work is to integrate the thin-film delafossite with MRAM devices for energy-efficient memory applications. |