An orbitally derived single-atom magnetic memory

• Published in: Nature communications Vol. 9; no. 1; pp. 3904 - 8
• Main Authors: Kiraly, Brian, Rudenko, Alexander N., van Weerdenburg, Werner M. J., Wegner, Daniel, Katsnelson, Mikhail I., Khajetoorians, Alexander A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25.09.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 147/138; 639/766/119/1001; 639/766/119/997; Bistability; Charge density; Gating; Humanities and Social Sciences; Information storage; Magnetic moments; Magnetic storage; multidisciplinary; Orbital stability; Phosphorus; Remanence; Scaling; Science; Science (multidisciplinary); Storage; Valency
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-06337-4

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. Single-atom storage can dramatically exceed the limit of traditional high-density memory devices but is challenging. Here the authors show the bistability in the orbital configuration of a single Co atom on black phosphorus which can be accessed, manipulated and has potential for high-temperature single-atom information storage.