Electrically driven singlet-triplet transition in triangulene spin-1 chains

TL;DR

This paper investigates electrically controllable singlet-triplet transitions in graphene triangulene spin-1 chains, combining theoretical calculations of exchange interactions with proposed experimental methods for manipulation.

Contribution

It introduces a detailed analysis of exchange constants in triangulene chains and proposes three experimental approaches, including electric field control, to induce spin transitions.

Findings

Exchange bilinear and biquadratic constants calculated for triangulene chains.

Three experimental methods proposed to trigger singlet-triplet transitions.

Electric field effectively controls the spin transition.

Abstract

Recently, graphene triangulene chains have been synthesized and their magnetic response has been analyzed by STM methods by Mishra and coworkers (Nature 598, 287 (2021)). Motivated by this study, we determine the exchange bilinear and biquadratic constants of the triangulene chains by calculating two-spin rotations in the spirit of the magnetic force theorem. We then analyze open-ended, odd-numbered chains, whose edge states pair up forming a triplet ground state. We propose three experimental approaches that enable us to trigger and control a singlet-triplet spin transition. Two of these methods are based on applying a mechanical distortion to the chain. We finally show that the transition can be controlled efficiently by the application of an electric field.