Robust fully spin-polarized nodal chain in 3D metal-organic framework

Abstract

The identification of fully spin-polarized topological phases in magnetic inorganic materials has attracted significant attention. In this study, through first-principles calculations, we characterize CrCl2(pyz)2, a metal-organic framework (MOF), as a nodal chain semimetal. Our results reveal a ferromagnetic ground state in this material, presenting as a half-metal with a single spin channel near the Fermi level. Specifically, the spin-down states form a nodal chain close to the Fermi level, consisting of three nodal loops protected by glide mirror symmetry on distinct planes. Furthermore, fully spin-polarized drumhead surface states corresponding to these nodal loops are identified on the material's surfaces. Remarkably, we observe the persistence of the fully spin-polarized nodal chain even when tuning the ligand rotation angle of the MOF.Furthermore, our investigation delves into the influence of spin-orbit coupling (SOC) on the system, revealing that it has minimal impact on the nodal chain. The robustness of the nodal chain in the presence of SOC underscores its intriguing and resilient nature, indicating its potential utility in various electronic applications. Ultimately, the robust realization of a fully spin-polarized nodal chain in this magnetic MOF system holds promise for applications in the realm of spintronics.