# Ground-state spin blockade in a single-molecule junction

## TL;DR

This paper demonstrates ground-state spin blockade in a high-spin single-molecule transistor, showing how spin differences can suppress current and how magnetic and electric fields can reversibly lift this blockade.

## Contribution

The first direct experimental observation of ground-state spin blockade in a high-spin single-molecule transistor, with tunable control via magnetic and electric fields.

## Key findings

- Complete suppression of resonant transport due to spin difference of 3/2.
- Reversible lifting of blockade through magnetic ground-state transition.
- Transport characteristics confirm the impact of spin states on electron flow.

## Abstract

It is known that the quantum-mechanical ground state of a nano-scale junction has a significant impact on its electrical transport properties. This becomes particularly important in transistors consisting of a single molecule. Due to strong electron-electron interactions and the possibility to access ground states with high spins, these systems are eligible hosts of a current-blockade phenomenon called ground-state spin blockade. This effect arises from the inability of a charge carrier to account for the spin difference required to enter the junction, as that process would violate the spin selection rules. Here, we present a direct experimental demonstration of ground-state spin blockade in a high-spin single-molecule transistor. The measured transport characteristics of this device exhibit a complete suppression of resonant transport due to a ground-state spin difference of 3/2 between subsequent charge states. Strikingly, the blockade can be reversibly lifted by driving the system through a magnetic ground-state transition in one charge state, using the tunability offered by both magnetic and electric fields.