Spin-resolved and charge Josephson diode effects in α − T 3 lattice junctions

The nonreciprocity of critical supercurrents in a Josephson device, termed the Josephson diode effect (JDE), has drawn considerable interest recently. Herein, we present possible spin-resolved and charge JDEs in a Josephson junction based on the $\ensuremath{\alpha}\text{\ensuremath{-}}{T}₃$ lattice, due to different spin-resolved Fermi velocities in opposite directions for the distorted flat bands and edge states. Two mechanisms are exhibited, which are characterized by a topological phase with an anisotropic parameter $\ensuremath{\alpha}$. One is that the JDE only originates from distorted flat bands, corresponding to the topological phase $(0<\ensuremath{\alpha}<0.5)$, the other simultaneously from edge states in the topological phase $(0.5<\ensuremath{\alpha}<1)$. Particularly, the charge JDE only manifests in the context of magnetization and its efficiency can range from $\ensuremath{-}45%$ to $39%$, suggesting a high nonreciprocity. More importantly, both the magnitude and polarity of the charge JDE from edge states and distorted flat bands can be strongly adjusted by the magnetization strength.