Time evolution of a pumped molecular magnet-A time-resolved inelastic neutron scattering study

Area of Science:

• Condensed Matter Physics
• Quantum Magnetism
• Materials Science

Background:

• Molecular magnets, such as Cr8F8Piv16, exhibit complex magnetic interactions and quantum ground states.
• Understanding the dynamics of excited states in these materials is crucial for potential applications in quantum technologies.
• Previous studies lacked direct observation of excited state populations and relaxation dynamics under external stimuli.

Purpose of the Study:

• To investigate the time-dependent effects of resonant microwave pulses on the molecular magnet Cr8F8Piv16.
• To measure the populations of various energy levels, including ground and excited states, during and after microwave irradiation.
• To determine the spin-lattice thermalization time scales in this molecular antiferromagnet.

Main Methods:

• Development and application of time-resolved inelastic neutron scattering (TRINS) technique.
• Utilized a 4.6 tesla magnetic field to tune energy level splitting into resonance with 105 GHz microwaves.
• Cooled Cr8F8Piv16 crystal to 1.9 K and applied 20-second microwave pulses along the (101) direction.

Main Results:

• Observed underpopulation of the ground state [Formula: see text] relative to thermal equilibrium at elevated spin temperatures.
• Determined spin-lattice thermalization time scales ranging from 1.6(2) s to 5.7(2) s, dependent on microwave power.
• TRINS provided a first-time view of long-lived excited states in a molecular antiferromagnet under intense microwave pumping.

Conclusions:

• TRINS is a powerful technique for probing the dynamic behavior of quantum magnetic materials.
• Resonant microwave excitation can significantly alter the population distribution of energy levels in molecular magnets.
• The observed long relaxation times suggest potential for coherent manipulation of quantum states in Cr8F8Piv16.