Realizing Two-Dimensional Spin Arrays on Surfaces via Halogen-Bonding Molecular Self-Assembly

Well-ordered spin arrays are highly desirable for next-generation molecule-based magnetic devices, and yet its synthetic method remains a challenging task. Herein, we demonstrate the realization of two-dimensional supramolecular spin arrays on surfaces via halogen-bonding molecular self-assembly. A bromine-terminal perchlorotriphenymethyl radical with net carbon spin was synthesized and deposited on Au(111) to achieve two-dimensional supramolecular spin arrays. By taking advantage of the diversity of halogen bonds, five supramolecular spin arrays are presented with ultrahigh spin densities (up to the value of 3 × 10¹³ spins at the size of a flash drive), as probed by low-temperature scanning tunneling microscopy at the single-molecule level. First principle calculations verify that the formation of three distinct types of halogen bonds can be used to tailor supramolecular phases via molecular coverage and annealing temperature. Our work demonstrates supramolecular self-assembly as a promising method to engineering 2D spin arrays for potential application in magnetic devices.