Mengting Zou

Equiatomic B2-ordered FeRh alloy possesses unique metamagnetic phase transition above room temperature, which provides a promising route for emerging magnetic recording and spintronic applications when downsized into nanoscale. This paper presents a systematic investigation of magnetic domain in single crystal FeRh films patterned into nanoscale stripe, ring, and circle geometries to explore the evolution of involved transition behavior and magnetic anisotropy. When the characteristic size of the patterns approaches 100 nm, a pronounced supercooling phenomenon occurs; particularly in the circle patterns, the supercooling degree exceeds 15 K. This finding reveals a suppression of the conventional heterogeneity-driven antiferromagnetic nucleation mechanism by dimensional confinement related to the pattern area. Concurrently, the dimensional confinement reduces the demagnetization energy, which enables ferromagnetic FeRh to maintain robust perpendicular magnetic anisotropy up to 390 K and across a wide temperature window of 45 K. Our work not only provides a deep insight into the metamagnetic phase transition mechanism at nanoscale but also is beneficial for realizing novel device functionalities utilizing nanosized FeRh.

Spin valves have received significant attention in the realm of flexible magnetic materials and devices due to their advantages of rapid response and high integration. Despite these benefits, the practical application of spin valves in wearable devices is constrained by their low stretchability and strain stability under tensile strain. Here, by designing spin valves with zigzag-wrinkled structure, we demonstrated that the magnetotransport properties of our spin valves remained unaffected under 25% biaxial tensile strain, revealing stretchability and strain stability. These outstanding performances are related to the zigzag-wrinkled structure generated after releasing the biaxial pre-strain in PDMS substrates. The flattening of the zigzag wrinkles under biaxial tensile strain releases the direct effect of strain on the metal multilayers, thereby maintaining sensing performances upon stretching. This innovative design paves the way for the development of robust, flexible magnetic devices suitable for wearable technology.