Ultraslow Relaxation of Toroidal State in Ferrotoroidal Dysprosium Complex

Area of Science:

• Molecular magnetism
• Quantum information science (QIS)
• Materials chemistry

Background:

• Molecular systems are promising for quantum information science (QIS) due to tunable quantum properties.
• Molecular nanomagnets (MNMs) are explored as qubits, but long coherence times and readouts are challenging.
• Single-molecule toroics (SMTs) offer potential but realizing ferrotoroidal (FT) states and demonstrating slow relaxation remains difficult.

Purpose of the Study:

• To design and synthesize a molecular complex with a stable ferrotoroidal (FT) ground state.
• To experimentally demonstrate and characterize the slow relaxation of toroidal states in a molecular system.
• To explore the potential of such systems for quantum information science (QIS) applications.

Main Methods:

• Synthesis and characterization of a tridecanuclear [Ga7Dy6(N-mdea)6(ClCH2COO)6(NO3)6(OH)12(H2O)6]·3Cl complex (1).
• Magnetic measurements using μSQUID to confirm the FT ground state.
• Ab initio calculations to corroborate the experimental findings.
• Analysis of quantum tunneling of magnetization (QTM) relaxation dynamics.

Main Results:

• The synthesized complex (1) exhibits a robust ferrotoroidal (FT) ground state.
• Experimentally observed slow relaxation of toroidal states for the first time, with a QTM relaxation time of ~3.5 × 10^8 s (~11 years).
• Achieved relaxation times significantly longer than state-of-the-art Dy(III)-based single-molecule magnets.
• FT ground state confirmed by μSQUID and ab initio calculations.

Conclusions:

• The study reports the first molecular system with an experimentally verified FT ground state and slow toroidal relaxation.
• The observed ultraslow relaxation, attributed to quenched many-body tunneling, is a significant advancement for molecular quantum devices.
• This work provides a new design paradigm for molecular complexes in QIS, paving the way for toroidal states in quantum technologies.