Jacobse Peter H, Sarker Mamun, Saxena Anshul, Zahl Percy, Wang Ziyi, Berger Emma, Aluru Narayana R, Sinitskii Alexander, Crommie Michael F
Department of Physics, University of California, Berkeley, Berkeley, CA, 94720, USA.
Department of Chemistry, University of Nebraska, Lincoln, NE, 68588, USA.
Small. 2024 Jul;20(30):e2400473. doi: 10.1002/smll.202400473. Epub 2024 Feb 27.
Carbon-based quantum dots (QDs) enable flexible manipulation of electronic behavior at the nanoscale, but controlling their magnetic properties requires atomically precise structural control. While magnetism is observed in organic molecules and graphene nanoribbons (GNRs), GNR precursors enabling bottom-up fabrication of QDs with various spin ground states have not yet been reported. Here the development of a new GNR precursor that results in magnetic QD structures embedded in semiconducting GNRs is reported. Inserting one such molecule into the GNR backbone and graphitizing it results in a QD region hosting one unpaired electron. QDs composed of two precursor molecules exhibit nonmagnetic, antiferromagnetic, or antiferromagnetic ground states, depending on the structural details that determine the coupling behavior of the spins originating from each molecule. The synthesis of these QDs and the emergence of localized states are demonstrated through high-resolution atomic force microscopy (HR-AFM), scanning tunneling microscopy (STM) imaging, and spectroscopy, and the relationship between QD atomic structure and magnetic properties is uncovered. GNR QDs provide a useful platform for controlling the spin-degree of freedom in carbon-based nanostructures.
碳基量子点（QDs）能够在纳米尺度上灵活操控电子行为，但控制其磁性需要原子级精确的结构控制。虽然在有机分子和石墨烯纳米带（GNRs）中观察到了磁性，但尚未报道能够自下而上制备具有各种自旋基态的量子点的GNR前体。本文报道了一种新型GNR前体的开发，该前体可形成嵌入半导体GNRs中的磁性量子点结构。将一个这样的分子插入GNR主链并使其石墨化，会形成一个容纳一个未配对电子的量子点区域。由两个前体分子组成的量子点表现出非磁性、反铁磁性或反铁磁基态，这取决于决定每个分子自旋耦合行为的结构细节。通过高分辨率原子力显微镜（HR-AFM）、扫描隧道显微镜（STM）成像和光谱学证明了这些量子点的合成以及局域态的出现，并揭示了量子点原子结构与磁性之间的关系。GNR量子点为控制碳基纳米结构中的自旋自由度提供了一个有用的平台。
