(a) Plan-view TEM images of annealed (FeRh)5Cu95 ribbons showing the presence of nanoprecipitates with ∼10–15 nm diameters in micron-scaled grains of Cu. (b) TEM diffraction pattern of annealed (FeRh)5Cu95 ribbons showing that the precipitates have an orientational relationship with the Cu matrix. Arrows indicate the crystallographic orientation corresponding to the precipitate reflections.
(a) Schematic illustration of the L10-type ordered crystal structure of the FeRh nanoprecipitates. (b) Schematic illustration of the relationship between the B2 and L10 crystal phases of FeRh (also known as Bain correspondence).
Low-temperature zero-field-cooled susceptibility of (FeRh)5Cu95 ribbons showing evidence of a spin-glass phase. The blocking temperature (Tb ) of the spin-glass phase is defined at the peak of the susceptibility curves χ(T). Annealing decreases Tb .
ZFC and FC temperature-dependant magnetization curves of (FeRh)5Cu95 ribbons in as-quenched as well as annealed conditions (H = 100 Oe). Arrows indicate the presence of the secondary phase with a magnetic transition at T ∼ 130 K which forms upon annealing.
(a) An expanded view of the zero-field-cooled temperature-dependent magnetization curve for (FeRh)5Cu95 ribbons annealed to 500 °C. (b) Temperature dependence of the magnetic moment of the annealed (FeRh)5Cu95 ribbons after subtraction of the paramagnetic background.
(a) Thermal hysteresis in the field-cooled magnetization curve of (FeRh)5Cu95 ribbons annealed to 500 °C identifies a first-order-like transition that is typical of bulk FeRh. (b) Evolution of the magnetic transition at T = 130 K with annealing temperature reveals that while the onset of ferromagnetism at T = 130 K becomes more pronounced, the apparent Curie temperature Tc of the secondary phase appears to increase with increase in annealing temperature.
Magnetic behavior of (FeRh)5Cu95 ribbons in the high-temperature regime (T ≥ 200 K) indicates co-existence of paramagnetic and ferromagnetic phases. (a) Field-dependent magnetization behavior of the (FeRh)5Cu95 ribbons as a function of annealing temperature. (b) Annealing at higher temperatures increases the Ms of the ferromagnetic phase while decreasing the χ of the paramagnetic phase.
Crystallographic properties of the L10 crystal structure of FeRh, FePt, and FePd.
Curie constant (C), paramagnetic Curie temperature (θ), and Pauli paramagnetic susceptibility (χ pp ) of the as-spun and annealed (FeRh)5Cu95 ribbons as obtained from fit of data to . a
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