Spin blockade in a charge-switchable molecular magnet

TL;DR

This paper explores how adding a single electron to a molecular magnet can switch its total spin from zero to a maximum value, revealing charge-sensitive magnetic states detectable via transport spectroscopy.

Contribution

It demonstrates the charge-induced spin switching mechanism in a molecular magnet using a generic model, highlighting the role of the Nagaoka mechanism in this process.

Findings

Charge modulation can switch molecular spin from 0 to 3/2.

Maximal spin states produce observable transport signatures.

Experimental detection via spin blockade and negative differential conductance.

Abstract

We consider the effect of adding electrons to a single molecule on its magnetic properties and the resulting transport fingerprints. We analyze a generic model for a metal-organic complex consisting of orbitals with different Coulomb repulsions. We find that by modulating the charge of the molecule by a single electron the total spin can be switched from zero to the maximal value supported by the added electrons, $S=3/2$. The Nagaoka mechanism is responsible for this charge-sensitivity of the molecular spin. It is shown that fingerprints of these maximal spin states, either as groundstates or low-lying excitations, can be experimentally observed in current-spectroscopy. as either spin blockade at low bias voltage or negative differential conductance and complete current suppression at finite bias.