Intrinsic Rashba effect and anomalous valley Hall effect in one-dimensional magnetic nanoribbon

Abstract

Stable one-dimensional (1D) magnetic nanoribbons are superior to the two-dimensional (2D) or bulk materials due to the quantum size effect and edge effect as well as the controllable bandwidth. Through first-principles calculations, Wannier functions and Monte Carlo simulation, it is found that the GdX2 (X = Cl, Br) zigzag nanoribbons (ZNRs) are dynamically stable, with Curie temperature of ferromagnetic ground state significantly higher than that of their 2D counterpart. The results show that inherent transverse dipole moment and perpendicular magnetocrystalline anisotropy energy (PMAE) induce the coexistence of Rashba effect and valley polarization in such 1D magnetic ZNRs. GdBr2 ZNR with four zigzag chains (GdBr2-4ZNR) has larger valley splitting and PMAE than that of GdCl2-4ZNR, demonstrating room temperature ferromagnetic ground state. Through regulating the bandwidth of GdBr2 ZNR, intrinsic anomalous valley Hall (AVH) effect is observed in GdBr2-5ZNR. Importantly, Dirac-cone-like electronic states, PMAE and AVH effect are robust against the increment of nanoribbon bandwidth which is essential for utilization. These results provide important insights and pave an avenue for the potential application of magnetic nanoribbons in spin-dependent and valley-dependent miniature information storage devices.