Electronic, magnetic and transport properties of a triangle graphene quantum dot have been studied in the presence of Rashba type spin–orbit coupling. The non-interacting part is written in the tight-binding model, and we use the Kene–Mele–Hubbard (KMH) Hamiltonian to describe the electron–electron and the Rashba spin–orbit interaction. While the Hubbard term split the spin up and down states, the Rashba term mixed these states. The competition between these two effects produces an interesting situation in a nano-device. Our results indicate that the magnetization of zigzag edge and spin coherence are decreased due to the Rashba spin–orbit interaction in the triangle graphene quantum dot. It is shown that the reduction of spin coherence is non-negligible even in the case of weak Rashba spin–orbit interaction.

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