Scientists demonstrated control over room temperature magnetism in a van der Waals magnet by tuning the crystal chemistry. Modifying the magnetic properties in cleavable materials will enable logical designs of information technologies and help test fundamental theories of magnetism.
Fe5GeTe2 has the highest ferromagnetic Curie temperature of the cleavable crystals, making it a prime candidate for spintronic applications. The crystal structures and physical properties were studied to establish how As substitution impacts the complex magnetic behavior in Fe5GeTe2; properties of the new material Fe5AsTe2 were also investigated. This result will motivate efforts to understand how fine-tuning the chemistry and charge counting impacts properties in various cleavable, metallic magnets.