Encoding information onto the charge and spin state of a paramagnetic atom using MgO tunnelling spintronics

TL;DR

This paper demonstrates that commercialized MgO-based magnetic tunnel junctions can be engineered to exhibit atom-level quantum transport phenomena, including spin blockade and memory effects, paving the way for industrial quantum device applications.

Contribution

It introduces a practical device platform that leverages atomic modifications in MgO barriers to achieve controllable quantum transport effects at the atomic scale.

Findings

Insertion of C atoms creates nanotransport paths.

Quantum interferences and spin blockade effects are observed.

Persistent memory effects linked to single-atom charging.

Abstract

An electrical current that flows across individual atoms can generate exotic quantum transport signatures in model junctions built using atomic tip or lateral techniques. So far, however, a viable industrial pathway for atom-driven devices has been lacking. Here, we demonstrate that a commercialized device platform can fill this nanotechnological gap. According to conducting tip atomic force microscopy, inserting C atoms into the MgO barrier of a magnetic tunnel junction generates nanotransport paths. Within magnetotransport experiments, this results in quantum interferences, and in Pauli spin blockade effects linked to tunneling magnetoresistance peaks that can be electrically controlled. We report an additional persistent memory effect that we attribute to the charging of a single "gating" C atom that is adjacent to a single C atom forming the microscale junction's effective nanotranport path. Local magnetometry experiments confirm the secondary role of magnetic stray fields on the C atoms. Our results show that, to exhibit atom-level properties, a device need not be nanoscaled, and position MgO tunneling spintronics as a promising platform to industrially implement quantum technologies.