Mechanical Control of Spin States in Spin-1 Molecules and the Underscreened Kondo Effect

TL;DR

This paper demonstrates electrical control of spin states in single spin-1 molecules and investigates the underscreened Kondo effect, providing insights into spin manipulation and correlated electron phenomena at the molecular scale.

Contribution

It introduces a method to controllably manipulate spin states in single-molecule devices without magnetic fields, enabling detailed studies of the underscreened Kondo effect.

Findings

Controlled spin state manipulation via molecular symmetry modification

Observation of the underscreened Kondo effect in single molecules

Establishment of molecular devices as models for correlated-electron theories

Abstract

The ability to make electrical contact to single molecules creates opportunities to examine fundamental processes governing electron flow on the smallest possible length scales. We report experiments in which we controllably stretch individual cobalt complexes having spin S = 1, while simultaneously measuring current flow through the molecule. The molecule's spin states and magnetic anisotropy were manipulated in the absence of a magnetic field by modification of the molecular symmetry. This control enabled quantitative studies of the underscreened Kondo effect, in which conduction electrons only partially compensate the molecular spin. Our findings demonstrate a mechanism of spin control in single-molecule devices and establish that they can serve as model systems for making precision tests of correlated-electron theories.