Kinetic arrest of the ferromagnetic state in Mn$$_3$$GaC and Ni$$_2$$MnGa composite mixtures

The kinetics of the ferromagnetic to antiferromagnetic transition in Mn$$_3$$ 3 GaC can be arrested and its magnetic properties can be tuned by mixing a small amount ($$\sim $$ ∼ 10%) of Heusler Ni$$_2$$ 2 MnGa to Mn$$_3$$ 3 GaC. A detailed study of magnetic properties of composite mixtures of Mn$$_3$$ 3 GaC and Ni$$_2$$ 2 MnGa with different antiperovskite to Heusler ratio, reveals that the ferromagnetic Ni$$_2$$ 2 MnGa polarizes magnetic spins of the antiperovskite phase by creating a magnetic strain field in its vicinity. The Heusler phase acts as a defect centre whose influence on the magnetic properties of the majority antiperovskite phase progressively diminishes, creating a distribution of transition temperatures. Such strong interaction between the two phases of the mixture allows for tunability and control over the properties of such magneto-structurally transforming materials.

Laser-Assisted Floating Zone Growth of BaFe2S3 Large-Sized Ferromagnetic-Impurity-Free Single Crystals

The quasi-one-dimensional antiferromagnetic insulator BaFe2S3 becomes superconducting under a hydrostatic pressure of ∼10 GPa. Single crystals of this compound are usually obtained by melting and further slow cooling of BaS or Ba, Fe, and S, and are small and needle-shaped (few mm long and 50–200 μm wide). A notable sample dependence on the antiferromagnetic transition temperature, transport behavior, and presence of superconductivity has been reported. In this work, we introduce a novel approach for the growth of high-quality single crystals of BaFe2S3 based on a laser-assisted floating zone method that yields large samples free of ferromagnetic impurities. We present the characterization of these crystals and the comparison with samples obtained using the procedure reported in the literature.