Ferrotoroidic Ground State in a Heterometallic Cr$^{\mathrm{III}}$Dy$^{\mathrm{III}}_6$ Complex Displaying Slow Magnetic Relaxation

TL;DR

This study reports a CrIII-DyIII6 complex with a ferrotoroidic ground state, demonstrating slow magnetic relaxation due to ferrotoroidic interactions, which is promising for quantum computing and multiferroic applications.

Contribution

The paper introduces a new heterometallic complex exhibiting a ferrotoroidic ground state driven by intramolecular dipolar interactions, advancing the understanding of ferrotoroidic coupling in molecular systems.

Findings

The complex displays a ferrotoroidic ground state with enhanced toroidal moment.

Magnetic relaxation is significantly slowed by ferrotoroidic states despite quantum tunneling.

Zero-field hysteretic spin dynamics observed at sub-Kelvin temperatures.

Abstract

Toroidal quantum states are most promising for building quantum computing and information storage devices as they are insensitive to homogeneous magnetic fields, but interact with charge and spin currents, allowing this moment to be manipulated purely by electrical means. Coupling molecular toroids into larger toroidal moments via ferrotoroidic interactions can be pivotal not only to enhance ground state toroidicity, but also to develop materials displaying ferrotoroidic ordered phases, which sustain linear magneto-electric coupling and multiferroic behaviour. However, engineering ferrotoroidic coupling is known to be a challenging task. Here we have isolated a Cr$^{\mathrm{III}}$Dy$^{\mathrm{III}}_6$ complex, which exhibits the much sought-after ferrotoroidic ground state with an enhanced toroidal moment, solely arising from intramolecular dipolar interactions. Moreover, a theoretical analysis of the observed sub-Kelvin zero-field hysteretic spin dynamics of Cr$^{\mathrm{III}}$Dy$^{\mathrm{III}}_6$ reveals the pivotal role played by ferrotoroidic states in slowing down the magnetic relaxation, in spite of large calculated single-ion quantum tunnelling rates.