Sun Kewei, Cao Nan, Silveira Orlando J, Fumega Adolfo O, Hanindita Fiona, Ito Shingo, Lado Jose L, Liljeroth Peter, Foster Adam S, Kawai Shigeki
International Center for Young Scientists, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
Center for Basic Research on Materials, National Institute for Materials Sciences, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
Sci Adv. 2025 Feb 28;11(9):eads1641. doi: 10.1126/sciadv.ads1641.
Magnetic exchange interactions between localized spins in π-electron magnetism of carbon-based nanostructures have attracted tremendous interest due to their great potential for nano spintronics. Unique many-body quantum characteristics, such as gaped excitations, strong spin entanglement, and fractionalized excitations, have been demonstrated, but the spin-1/2 Heisenberg model with a single antiferromagnetic coupling value remained unexplored. Here, we realized the entangled antiferromagnetic quantum spin-1/2 Heisenberg model with diazahexabenzocoronene oligomers (up to 7 units) on Au(111). Extensive low-temperature scanning tunneling microscopy/spectroscopy measurements and density functional theory and many-body calculations show that even-numbered spin chains host a collective state with gapped excitations, while odd-numbered chains feature a Kondo excitation. We found that a given antiferromagnetic coupling value between first neighbors in the entangled quantum states is responsible for the quantum phenomena, strongly relating to their parities of the chain. The tunable molecular building blocks act as an ideal platform for the experimental realization of topological spin lattices.
碳基纳米结构的π电子磁性中局域自旋之间的磁交换相互作用因其在纳米自旋电子学方面的巨大潜力而引起了极大的关注。独特的多体量子特性，如能隙激发、强自旋纠缠和分数化激发，已得到证实，但具有单一反铁磁耦合值的自旋-1/2海森堡模型仍未得到探索。在此，我们在Au(111)上用二氮杂六苯并蔻低聚物（最多7个单元）实现了纠缠反铁磁量子自旋-1/2海森堡模型。广泛的低温扫描隧道显微镜/光谱测量以及密度泛函理论和多体计算表明，偶数自旋链拥有具有能隙激发的集体态，而奇数自旋链具有近藤激发。我们发现，纠缠量子态中第一近邻之间给定的反铁磁耦合值是量子现象的原因，这与它们的链奇偶性密切相关。可调节的分子构建块为拓扑自旋晶格的实验实现提供了理想平台。
