A magnetic atom epitomizes the scaling limit for magnetic information storage. Individual atomic spins have recently exhibited magnetic remanence, a requirement for magnetic memory. However, such memory has been only realized on thin insulating surfaces, removing potential tunability via electronic gating or exchange-driven magnetic coupling. Here, we show a previously unobserved mechanism for single-atom magnetic storage based on bistability in the orbital population, or so-called valency, of an individual Co atom on semiconducting black phosphorus (BP). Ab initio calculations reveal that distance-dependent screening from the BP surface stabilizes the two distinct valencies, each with a unique orbital population, total magnetic moment, and spatial charge density. Excellent correspondence between the measured and predicted charge densities reveal that such orbital configurations can be accessed and manipulated without a spin-sensitive readout mechanism. This orbital memory derives stability from the energetic barrier to atomic relaxation, demonstrating the potential for high-temperature single-atom information storage.

中文翻译：

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轨道导出的单原子磁存储器。

磁性原子代表了磁性信息存储的缩放限制。各个原子自旋最近展现出剩磁，这是磁记忆的必要条件。然而，这种存储器仅在薄的绝缘表面上实现，从而通过电子门控或交换驱动的磁耦合消除了潜在的可调性。在这里，我们显示了一种基于半导体黑磷（BP）上单个Co原子的轨道总体上的双稳态或所谓的化合价的单原子磁存储的先前未曾观察到的机制。从头算计算表明，从BP表面进行依赖于距离的筛选稳定了两个不同的化合价，每个化合价具有唯一的轨道数，总磁矩和空间电荷密度。测量和预测的电荷密度之间的出色对应关系表明，无需自旋敏感的读出机制，就可以访问和操纵这种轨道构型。该轨道记忆从高能势垒到原子弛豫获得了稳定性，证明了高温单原子信息存储的潜力。