Magnetic anisotropy of high-entropy oxides with negative Poisson's ratio

High-entropy oxide (HEO) materials have recently been extensively studied and attracted unprecedented attention. The HEO can be regulated by introducing different atomic species, resulting in excellent physical properties. Herein, we fabricated the spinel HEO (Cr,Mn,Fe,Co,Ni)3O4 (CMFCN) film with various of thicknesses on perovskite STO substrate by PLD technology. Interestingly, all the CMFCN films exhibit negative Poisson's ratio behavior and demonstrate ferrimagnetic behavior at room temperature. The strain-induced Poisson's ratio significantly affects the magnetism of the HEO film. The magnetic anisotropy decreases as the Poisson's ratio decreases, while coercivity increases from ∼270 to ∼1700 Oe. The axis of easy magnetization changes from in-plane to out-of-plane. These results indicate that the thickness-modulated magnetic of HEO epitaxial films has potential applications in integrating magnetic insulating oxides with spintronics.