Electronic Control of Spin Alignment in pi-Conjugated Molecular Magnets

TL;DR

This paper presents a theoretical study on controlling spin alignment in pi-conjugated molecules, showing how electronic doping can induce transitions between different spin states, which explains recent experimental observations.

Contribution

It introduces a model combining Peierls-Hubbard chains with localized spins and demonstrates doping-induced spin state transitions, providing new insights into molecular spin control.

Findings

Doping induces singlet to quartet spin transitions.

Spin alignment depends on chain length and spin positions.

Theoretical results explain recent experimental spin observations.

Abstract

Intramolecular spin alignment in pi-conjugated molecules is studied theoretically in a model of a Peierls-Hubbard chain coupled with two localized spins. By means of the exact diagonalization technique, we demonstrate that a spin singlet (S=0) to quartet (S=3/2) transition can be induced by electronic doping, depending on the chain length, the positions of the localized spins, and the sign of the electron-spin coupling. The calculated results provides a theoretical basis for understanding the mechanism of spin alignment recently observed in a diradical donor molecule.