Models for Modern Spintronics Memories with Layered Magnetic Interfaces

Abstract

Spintronics memories are important members of the family of non-volatile memory systems. Magnetic random-access memory (MRAM) is a type of spintronic technology-based non-volatile memory. Recently, voltage-controlled magnetic anisotropy (VCMA) has attracted a lot of attention as it allows faster switching and lowers energy consumption compared to conventional spin-transfer torque (STT) based magnetization switching. This chapter discusses the read and write access time, switching speed, and power consumption of TST-MRAM cells using realistic material and device parameters. Subsequently, we elaborate a SPICE-based VCMA and mathematical Rashba SOI model that incorporates various design parameters, i.e., VCMA coefficient, time constant, saturation magnetization, external magnetic field, Hamiltonian field, and magnetic diffused field. In the magnetic interfaces consisting of heavy metal (HM), ferromagnetic (FM), nonmagnetic (NM) multilayers, and CoFeB/MgO composite, the highest switching probabilities of 94.6%, 84.4%, and 63.3% were achieved for VCMA coefficient values of 33 fJV−1m−1, 105 fJV−1m−1, and 290 fJV−1m−1, respectively. The read and write access time of TST-MRAM cells are increased by 1.5x and 1.25x compared to STT and SOT-MRAM cells. We also elaborate that the MRAM cell’s magnetization and Hamiltonian field should be maximum for better reliability and high-speed switching.