Research Projects

Quantum and spintronic materials are essential for the advancement of future technologies, owing to their unique properties that emerge from the interplay of atomic-level characteristics such as lattice structure, charge, orbital, and spin. These materials offer the potential for more efficient and significantly faster electronic systems. However, much of the existing research remains focused on fundamental studies or demonstrations involving individual devices, often at the early stages of application development. The proposed research aims to develop large-scale on-chip circuits incorporating quantum and spintronic devices, with the goal of enhancing output and providing greater flexibility compared to single-device configurations. These circuits will also enable multi-input and output control capabilities. The proposal will focus on three systems for large-scale circuit demonstrations: 1) Magnetic tunnel junction (MTJ)-based energy harvesters, harmonic generators, and signal transmitters; 2) Spin-orbit torque-based oscillators; and 3) Nonlinear topological materials for wideband rectifiers and RF mixers. MTJs are currently commercialized for magnetic random access memory (MRAM) applications. However, recent demonstrations have shown that MTJs can also be effective for energy harvesting when arranged in arrays. Despite this potential, chip-based limitations have hindered the scalability of these applications beyond a few MTJs. The PI, in collaboration with Tohoku University, plans to address these challenges by working on chip-based RF circuit implementations and developing a prototype. This prototype will be tested in India using the RF wired and wireless testing system outlined in this proposal. The ultimate goal is to develop an energy harvesting module capable of powering small on-chip electronics without battery. The second part of the proposal aims to develop spin-Hall nano-oscillator (SHNO) arrays, constructed from heavy metal and magnetic material bilayers, to operate across a broad frequency range. These arrays will be engineered for mutual synchronization and can be used in signal transmission, high-frequency rectification, and energy-efficient systems. While these systems are easier to fabricate and offer greater flexibility in control compared to MTJs, their output is limited, and it can only be enhanced by using arrays. The final system is based on nonlinear transport in topological insulators. While materials such as Bi2Te3 and SnTe have demonstrated notable nonlinear effects, their efficiency remains limited. Therefore, the focus of the array-based studies is to enhance the efficiency and to explore the behavior of quantum device-based circuits on large-scale arrays. While all of these systems will be developed in collaboration, the primary goal of this proposal is to establish RF testing facilities for evaluating these on-chip devices and to develop prototypes for an energy harvester, RF mixer, and wideband rectifier.