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Geometric-phase interference in a Mn12 single-molecule magnet with fourfold rotational symmetry
S T Adams1, E H da Silva Neto, S Datta
1Department of Physics, Amherst College, Amherst, Massachusetts 01002-5000, USA.
Physical Review Letters
|March 12, 2013
Summary
Researchers observed abrupt increases in magnetic relaxation rate in Mn(12)-tBuAc single-molecule magnets. This phenomenon, linked to geometric-phase interference, provides the first experimental evidence in fourfold symmetric systems.
Area of Science:
- Quantum magnetism
- Molecular magnetism
- Condensed matter physics
Background:
- Single-molecule magnets (SMMs) exhibit slow magnetic relaxation.
- Quantum tunneling of magnetization is a key phenomenon in SMMs.
- Geometric-phase interference effects can influence quantum tunneling.
Purpose of the Study:
- To investigate the magnetic relaxation rate (Γ) of Mn(12)-tBuAc.
- To explore the influence of transverse magnetic fields (H(T)) on tunneling resonances.
- To provide experimental evidence for geometric-phase interference in SMMs.
Main Methods:
- Measuring the magnetic relaxation rate (Γ) as a function of transverse magnetic field (H(T)).
- Utilizing a single-molecule magnet Mn(12)-tBuAc with fourfold symmetry.
- Performing detailed numerical calculations using the spin Hamiltonian.
Main Results:
- Abrupt increases in Γ were observed near quantum tunneling resonances.
- These increases occurred beyond magnetic field values where geometric-phase interference suppresses tunneling.
- The effect was suppressed by rotating the transverse magnetic field, confirming the role of interference.
Conclusions:
- The study presents the first experimental evidence of geometric-phase interference in a single-molecule magnet with true fourfold symmetry.
- The observed phenomena are accurately reproduced by numerical calculations.
- This work deepens the understanding of quantum tunneling dynamics in molecular magnets.
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