Tuning the magnetostructural phase transition in FeRh nanocomposites Available to Purchase

Effects of nanostructuring on the magnetostructural response of the near-equiatomic FeRh phase were investigated in nanocomposite materials synthesized by rapid solidification and subsequent annealing of an alloy of nominal atomic composition (FeRh)₅Cu₉₅. Transmission electron microscopy studies confirm attainment of a phase-separated system of nanoscaled (∼10–15 nm diameter) precipitates, consistent with FeRh embedded in a Cu matrix. These nanoprecipitates are crystallographically aligned with the coarse-grained Cu matrix and possess an L1₀-type (CuAu 1) structure, in contrast to the B2 (CsCl)-type structure of bulk FeRh. It is proposed that the face-centered cubic crystal structure of the Cu matrix serves as a template for the formation and stabilization of the L1₀ structure in the FeRh nanoprecipitates. Magnetic measurements highlight the existence of multiple magnetic phases in the material exhibiting spin-glass (T ≤ 15 K), ferromagnetic and paramagnetic (T > 20 K) behavior. A thermally hysteretic magnetic transition, remarkably similar to the magnetostructural transition of bulk CsCl-type FeRh reported at T_t = 370 K, is observed in the nanostructured material at 130 K. This result not only emphasizes the sensitivity of the magnetic and structural properties of FeRh to changes in microstructural scale, but also highlights the potential for tailoring magnetostructural transitions in functional materials systems via nanostructuring.