Giant spin-phonon bottleneck effects in evaporable vanadyl-based molecules with long spin coherence

Area of Science:

• Quantum magnetism
• Solid-state chemistry
• Materials science

Background:

• Vanadium(IV) complexes demonstrate exceptional quantum spin coherence times.
• Spin-lattice relaxation often limits coherence in these systems.
• Understanding environmental and vibronic effects is crucial for low-temperature dynamics.

Purpose of the Study:

• Investigate the role of environment and vibronic properties in low-temperature dynamics of VO(acac)2, VO(dpm)2, and VO(dbm)2 complexes.
• Examine the influence of crystallite size and ligand steric hindrance on magnetization dynamics.
• Elucidate the mechanism behind spin-lattice relaxation limitations.

Main Methods:

• Comparative study of magnetization dynamics across different crystallite sizes.
• Synthesis and characterization of VO(acac)2, VO(dpm)2, and VO(dbm)2 complexes with varying β-diketonate ligands.
• Density functional theory (DFT) calculations to develop an ad hoc force field model.

Main Results:

• Observed a significant crystallite size dependence of relaxation time up to 40 K.
• Identified a giant spin-phonon bottleneck effect as the cause of this dependence.
• Correlated the intensity of the phenomenon with ligand dimensions and unit cell size.

Conclusions:

• The crystallite size and ligand steric hindrance significantly impact spin-lattice relaxation in VO(IV) complexes.
• A giant spin-phonon bottleneck effect is a key factor in the observed relaxation dynamics.
• DFT-derived force field modeling provides insights into the structure-dynamics relationship.