Epitaxial Growth of Rare-Earth High-Entropy Alloy Thin Films.

The growth of high-entropy alloy (HEA) thin films using the molecular beam epitaxy (MBE) technique widens our horizons in materials design. This technique offers precise control of key parameters (deposition rate, substrate orientation, interfacial, or lattice strain), and it becomes possible to study the interplay existing between the elemental choice, their respective stoichiometry, and the associated physical and chemical properties. Such fine-tuning of HEA with an immense compositional space will bring additional advanced materials with exotic properties. Here, we report the epitaxial growth of a rare-earth (RE) HEA thin film on a buffer layer of Nb by MBE. The structure and chemistry of the DyGdHoLuTb thin film have been investigated in the bulk and at the surface under ultra-high vacuum (UHV) conditions, confirming a random chemical distribution on an ordered hexagonal closed-packed structure. We demonstrate how such a heterostructure exhibits magnetic properties that slightly depart from the magnetic phase diagram reported for polycrystalline materials of a similar system.