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arXiv · 2407.20996

Thermal spin-crossover and temperature-dependent zero-field splitting in magnetic nanographene chains

Yan Wang·Alejandro Pérez Paz·Emil Viñas Boström·Xiaoxi Zhang·Juan Li·Reinhard Berger·Kun Liu·Ji Ma·Li Huang·Shixuan Du·Hong-jun Gao·Klaus Müllen·Akimitsu Narita·Xinliang Feng·Angel Rubio·CA Palma
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Abstract

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.

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Yan Wang, Alejandro Pérez Paz, Emil Viñas Boström, Xiaoxi Zhang, Juan Li, Reinhard Berger, Kun Liu, Ji Ma, Li Huang, Shixuan Du, Hong-jun Gao, Klaus Müllen, Akimitsu Narita, Xinliang Feng, Angel Rubio, CA Palma. 2024-07-30. Thermal spin-crossover and temperature-dependent zero-field splitting in magnetic nanographene chains. https://arxiv.org/abs/2407.20996

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