Flat-band states induced negative differential resistance in organic-ferromagnetic devices

Spin-dependent transport via flat-band states in organic-ferromagnetic devices with spin radicals is investigated theoretically. A spin-resolved negative differential resistance phenomenon is observed together with a spin-filtering effect. A new mechanism as bias-induced distinct localization of the spin-split flat-band states is proposed, which originates from the weaker hybridization of the flat-band states rather than the π-conjugated orbitals. The peak-to-valley ratio increases with the interaction strength between the main chain and radicals. This work explores the unique transport property of flat-band states and their intriguing prospect in designing high-performed organic spintronic devices.