2024/07/30 by Yan Wang, Alejandro Pérez Paz, Wang, Yan +28
Materials Science · Physics and Astronomy · #2D Materials and Applications #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Graphene research and applications #Quantum and electron transport phenomena
paper · pdf · doi:10.48550/arxiv.2407.20996
openalex publication_date 2024/07/30 · openalex created_date 2024/08/01 · openalex updated_date 2026/07/28
Nanographene-based magnetism at interfaces offers an avenue to designer quantum materials towards novel phases of matter and atomic-scale applications. Key to spintronics applications at the nanoscale is bistable spin-crossover which however remains to be demonstrated in nanographenes. Here we show that antiaromatic 1,4-disubstituted pyrazine-embedded nanographene derivatives, which promote magnetism through oxidation to a non-aromatic radical are prototypical models for the study of carbon-based thermal spin-crossover. Scanning tunneling spectroscopy studies reveal symmetric spin excitation signals which evolve at Tc to a zero-energy peak, and are assigned to the transition of a S = 3/2 high-spin to a S = 1/2 low-spin state by density functional theory. At temperatures below and close to the spin-crossover Tc, the high-spin S= 3/2 excitations evidence pronouncedly different temperature-dependent excitation energies corresponding to a zero-field splitting in the Hubbard-Kanamori Hamiltonian. The discovery of thermal spin crossover and temperature-dependent zero-field splitting in carbon nanomaterials promises to accelerate quantum information, spintronics and thermometry at the atomic scale.