Researchers have achieved a high level of control over molecular magnetism with the creation of two new nanographenes, C62H22 and C76H26, synthesized using atomically precise on-surface chemistry. Building upon the established “Clar’s goblet” structure, the team from the National University of Singapore and collaborators engineered these molecules to host four unpaired spins, originating from differing mechanisms within each. This nuanced approach to spin behavior offers enhanced resilience to magnetic disruptions, a critical factor for advancing molecular-scale quantum technologies and spintronics. “Our work establishes a clear structure-property relationship in hourglass-shaped nanographenes through combined experimental and theoretical investigations,” said Professor Lu Jiong, establishing the potential for carbon-based molecular qubits and quantum simulators. The findings, published in Nature Synthesis, represent a significant step toward stable and controllable multi-spin entanglement.
Clar’s Goblet Extension Enables Tunable Nanographene Spin Configurations
Both newly created molecules contain four unpaired spins, yet these spins originate from fundamentally different mechanisms within each structure, revealing a nuanced ability to engineer spin configurations. The distinction in spin origin is critical; in one nanographene, the spins are solely dictated by the molecule’s geometric arrangement, while the other derives its spins from a combination of geometry and enhanced electron interactions. Characterization via scanning probe microscopy confirmed the structures and properties of these molecules, allowing researchers to compare their magnetic resilience under external perturbations. Despite both molecules possessing four correlated spins, one exhibited significantly greater robustness, maintaining its quantum state with increased stability, a crucial characteristic for potential applications in quantum computing. This enhanced resilience is particularly promising for molecular qubits, where preserving delicate quantum states is paramount for reliable information processing.
The team’s work, published in Nature Synthesis, expands the toolkit for molecular spintronics and lays the groundwork for future investigations into spin dynamics and coherence times at the single-molecule level. Professor Lu added, “Looking ahead, we aim to probe spin dynamics and coherence times at the single-molecule level, and to achieve coherent control of these entangled spins,” signaling a continued pursuit of functional quantum devices built from carbon-based materials.
Tetraradical Nanographenes Demonstrate Enhanced Resilience to Magnetic Perturbations
The pursuit of stable, controllable molecular spins for quantum technologies has largely focused on manipulating individual unpaired electrons within carefully designed structures; however, achieving resilience against external disturbances remains a significant hurdle for practical applications. Researchers are now demonstrating that precise control over molecular architecture can yield nanographenes exhibiting robust magnetic properties, moving beyond simply creating molecules with multiple spins to engineering their behavior. A team led by Professor Lu Jiong at the National University of Singapore, in collaboration with Professor Wu Jishan and Professor Pavel Jelínek from the Czech Academy of Sciences, has synthesized two novel nanographenes, C62H22 and C76H26, using a technique they term “atomically precise on-surface chemistry.” This technique allows for the construction of molecules with defined structures, going beyond traditional synthetic methods.
Both C62H22 and C76H26 contain four unpaired spins, a characteristic crucial for potential use in quantum information storage and processing, but the origin of these spins differs between the two molecules. This distinction is not merely academic; it directly impacts the molecules’ response to magnetic fields. Scanning probe microscopy measurements revealed that one molecule exhibited significantly greater resilience to magnetic perturbations than the other, meaning its quantum state remained stable even when exposed to external influences. The foundation for these new nanographenes was “Clar’s goblet,” a pre-existing molecular structure that provided a starting point for extending the carbon framework both laterally and vertically. This strategic approach allowed the researchers to independently tune electron interactions and the number of zero-energy modes within the molecules.
Our work establishes a clear structure-property relationship in hourglass-shaped nanographenes through combined experimental and theoretical investigations.
