Tunneling magnetoresistance in antiferromagnetic magnetic tunnel junctions

Abstract Magnetic random-access memory (MRAM) offers significant advantages in non-volatility, low power consumption, and high endurance and fast switching speed, making it an attractive solution for memory applications. The core structure, magnetic tunnel junctions (MTJs), has been successfully established in MRAM with high tunneling magnetoresistance (TMR) over the past two decades. However, ferromagnetic tunnel junctions (FM-MTJs) face limitations due to stray fields, GHz dynamics, and thermal stability, which impede further advancements in high-density and high-speed storage applications. In contrast, antiferromagnets (AFMs), with their inherent benefits of zero net magnetization, immunity to stray fields, and THz spin dynamics, present a promising alternative to overcome these challenges. Consequently, MTJs utilizing AFMs with notable TMR effects have garnered significant research interest. This review provides a comprehensive overview of the latest developments in TMR of antiferromagnetic tunnel junctions (AFM-MTJs), focusing on two main technical approaches: first, exchange bias MTJs, where substantial progress in device demonstration and chip integration is discussed; and second, all-AFM-MTJs, which highlight ongoing efforts to discover new AFM materials, develop prototype devices, and explore their underlying physical mechanisms. Finally, we discuss the future challenges and perspectives for these two AFM-MTJs technologies. As promising candidates for next-generation spintronic devices, compared to FM-MTJs, AFM-MTJs offer the potential to deliver high-density, low-power, and ultra-fast storage solutions for future memory applications.