Spin-polarized current in field-effect transistors made of magnetic polymers

This study theoretically explores the spin-polarized current ratio, conductivity, and spin moments in multilayered polymer field-effect transistors. Respective layers are formed by dimerized backbones with repeat units coupled to magnetic side-groups. We show that within a small interval of the gate voltage, a considerable formation of the non-zero spin-polarized current ratio is formed together with a considerable decrease of the current. We demonstrate that this phenomenon is correlated with the formation of an alternating (ferrimagnetic) spin alignment, resulting in a net spin moment, controlled by interaction couplings, such as electron–phonon, magnetic coupling, and intra-site Coulomb (Hubbard) interaction. We demonstrated that by tuning the Fermi energy of respective chains with an applied gate voltage, the spin polarization of the current can change its sign, with no change of the orientation of the total spin. These findings provide insights for optimizing the spin-polarized current ratio through gate voltage modulation and interaction couplings, offering potential applications in spintronic device design.