UCLA

Spintronics, or spin electronics, utilizes the spin property of electrons alongside their charge to enhance data processing and storage capabilities. This field has transformed from early magnetic navigation tools to foundational technologies in modern storage solutions like Hard Disk Drives and Magnetic Random Access Memory (MRAM). Furthermore, the development of Magnetoelectric Spin-Orbit (MESO) devices extends the utility of spintronics into logic operations, leveraging high-efficiency processes that could drastically reduce power consumption in future computing systems. MRAM is recognized as a promising non-volatile storage solution for mobile devices and microcontrollers, possibly replacing traditional memory types like last-level cache due to its speed and density. However, conventional Spin-Transfer-Torque (STT) MRAM is hindered by slow and energy-intensive writing operations. To overcome these limitations, we propose using Voltage-Controlled Magnetic Anisotropy (VCMA) for writing. Our research, through a collaboration between foundry and lab, has successfully integrated VCMA-based MRAM with CMOS technology, demonstrating ultra-fast switching times of 0.7 ns with a 1.8V write voltage and achieving read times of 8.5 ns with endurance exceeding 1011 cycles, validating VCMA-MRAM as a viable non-volatile memory option. Further, our study advances VCMA-based True Random Number Generators (TRNGs), crucial for cryptography. We have developed TRNGs that operate without the traditionally required external in-plane magnetic field by applying a 1.7 V, 5 ns pulse. This method meets the National Institute of Standards and Technology (NIST) standards for randomness and introduces a novel mechanism that allows for faster relaxation times compared to superparamagnetic systems, paving the way for TRNGs that are fast, compact, energy-efficient, and highly reliable. Additionally, MESO devices face challenges with spin-to-charge conversion efficiency. Topological insulators (TIs), with their unique topology-protected surface states, present a promising solution to enhance this efficiency. Our study identified that a Ru layer insertion between the TI and the magnet can boost conversion efficiency by 60%, highlighting the significant role of interface engineering. Additionally, we proposed and validated a physical model for the conversion between spin and charge in topological insulators, which can guide the further enhancement of efficiency. This research establishes a solid foundation for advancing spin-to-charge conversion technologies, opening new possibilities for their integration into future electronic devices.