An orbitally derived single-atom magnetic memory

TL;DR

This paper introduces a novel single-atom magnetic memory mechanism based on orbital bistability in cobalt atoms on black phosphorus, enabling electronic manipulation and potential high-temperature data storage.

Contribution

It presents a new orbital-based memory mechanism for single atoms on semiconductors, expanding tunability beyond spin-dependent methods.

Findings

Orbital bistability in Co atoms on black phosphorus enables magnetic memory.

Electronic manipulation of valency and magnetic moment without spin readout.

Potential for high-temperature single-atom information storage.

Abstract

A single magnetic atom on a surface epitomizes the scaling limit for magnetic information storage. Indeed, recent work has shown that individual atomic spins can exhibit magnetic remanence and be read out with spin-based methods, demonstrating the fundamental requirements for magnetic memory. However, atomic spin memory has been only realized on thin insulating surfaces to date, removing potential tunability via electronic gating or distance-dependent exchange-driven magnetic coupling. Here, we show a novel mechanism for single-atom magnetic information storage based on bistability in the orbital population, or so-called valency, of an individual Co atom on semiconducting black phosphorus (BP). Distance-dependent screening from the BP surface stabilizes the two distinct valencies and enables us to electronically manipulate the relative orbital population, total magnetic moment and spatial charge density of an individual magnetic atom without a spin-dependent readout mechanism. Furthermore, we show that the strongly anisotropic wavefunction can be used to locally tailor the switching dynamics between the two valencies. This orbital memory derives stability from the energetic barrier to atomic relaxation and demonstrates the potential for high-temperature single-atom information storage.