双自由基纳米石墨烯中的设计者自旋序
Designer spin order in diradical nanographenes
摘要：
由于碳材料在自旋电子学和量子计算中的潜在应用，碳材料的磁性是目前物理、化学和材料科学研究的热点。尽管最近已经证实了开壳纳米石墨烯中自旋的存在，但控制磁耦合符号的能力仍然难以捉摸，但却是最令人期望的。在这里，我们展示了一种有效的方法，工程磁基态在原子级精确的开壳层二分/非二分纳米石墨烯使用相结合的扫描探针技术和平均场哈伯德模型计算。通过打破纳米石墨烯的二分晶格对称性，控制了两个自旋之间的磁耦合符号。此外，两个自旋之间的交换相互作用强度已经通过精细地调整它们的自旋密度重叠而得到了广泛的调整，实现了42 meV的大交换相互作用强度。我们所展示的方法为设计师提供了充分的机会，在室温以上的石墨烯纳米材料的磁相和功能。
英文摘要：
The magnetic properties of carbon materials are at present the focus of an intense research effort in physics, chemistry and materials science due to their potential applications in spintronics and quantum computations. Although the presence of spins in open-shell nanographenes has been recently confirmed, the ability to control magnetic coupling sign has remained elusive, but the most desirable. Here, we demonstrate an effective approach of engineering magnetic ground states in atomically precise open-shell bipartite/nonbipartite nanographenes using combined scanning probe techniques and mean-field Hubbard model calculations. The magnetic coupling sign between two spins has been controlled via breaking bipartite lattice symmetry of nanographenes. In addition, the exchange-interaction strength between two spins has been widely tuned by finely tailoring their spin density overlap, realizing a large exchange-interaction strength of 42 meV. Our demonstrated method provides ample opportunities for designer above-room-temperature magnetic phases and functionalities in graphene nanomaterials.
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