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The practical applications for the distinctive functions of metamagnetic Heusler alloys, such as magnetic shape memory effect, various caloric effects, etc., strongly depend on the phase transition temperatures. Here, flexible Heusler alloy Ni–Mn–Sn films have been deposited on mica substrates by pulsed laser deposition with a Ti buffer layer. Clear ferromagnetic (FM) transition followed by the martensitic transformation at around room temperature and exchange bias (EB) with a blocking temperature of 70 K are observed. Under the application of both tensile and compressive strains by bending the mica substrates, all the characteristic temperatures of Ni–Mn–Sn films, including the FM transition temperature, martensitic transformation temperature, and blocking temperature of EB, are significantly increased by about 10 K. Furthermore, EB field and coercivity are both strongly strengthened, which is mainly caused by the simultaneous enhancement of FM and anti-FM Mn–Mn coupling because of their shortened separations by strain and verified by the Monte Carlo simulation results. The strain controlling for structural and magnetic properties provides efficient manipulation for Heusler alloy-based magnetic devices.

High-entropy alloys (HEAs) have attracted extensive research interest for their outstanding mechanical, electrochemical, and magnetic properties due to the highly random occupation of near equimolar multi-principal elements. The functionalities are severely influenced by the highly disordered lattice structure at grain boundaries and random orientation of grains in polycrystalline samples. Here, epitaxial CrMnFeCoNi HEA thin films of (001) orientation are prepared by laser-assisted molecular beam epitaxy on MgO substrates using a Cu buffer layer. A spontaneous exchange bias (SEB) effect is observed in a 98 nm thick CrMnFeCoNi HEA thin film. The SEB effect is related to a newly formed ferromagnetic (FM)/spin glass (SG) interface generated by field-induced irreversible growth of FM regions. The interfacial spins of SG domains are gradually consumed during the initial magnetizing process, leading to the consequent reservation of unidirectional anisotropy. The observation of SEB in HEA films expands their functions, which may be applied in novel magnetic devices.