Spin thermoelectric properties induced by hydrogen impurities in zigzag graphene nanoribbons.

This study investigates the impact of hydrogen impurities on the spin-dependent thermoelectric properties of zigzag graphene nanoribbons (ZGNRs) through density functional theory and the Landauer-Büttiker formula. Hydrogenation induces a net magnetism with a localized spin-dependent band around the Fermi energy in ZGNRs with different spin configurations, such as antiferromagnetic and ferromagnetic states. The results reveal spin-semiconducting behavior with a tunable energy gap and fully spin-polarized states in certain energy ranges. Application of a thermal gradient induces a thermal spin current, leading to the emergence of the spin Seebeck effect (SSE). By strategically placing a single hydrogen atom in various positions within the ZGNRs, we demonstrate that the hydrogen impurity's location significantly influences the spin-dependent thermoelectric properties, offering opportunities for enhanced thermoelectric performance through engineering. The observed spin thermocurrent and SSE in different impurity locations, considering both ferromagnetic and antiferromagnetic spin configurations, highlight the potential of hydrogenated ZGNRs in spin-dependent thermoelectric devices.