Observation of a level crossing in a molecular nanomagnet using implanted muons

Area of Science:

• Condensed Matter Physics
• Quantum Chemistry
• Materials Science

Background:

• Molecular nanomagnets (MNMs) are nanoscale materials exhibiting magnetic properties.
• Understanding the spin dynamics within MNMs is crucial for their technological applications.
• Muon spin relaxation is a sensitive probe of magnetic interactions and dynamics.

Purpose of the Study:

• To investigate electronic energy level crossings in a specific molecular nanomagnet.
• To demonstrate the sensitivity of muon spin relaxation to electronic spin dynamics.
• To provide evidence for spin transitions in MNMs.

Main Methods:

• Utilized muon spin relaxation spectroscopy.
• Investigated a broken ring MNM with the chemical formula [H(2)N(t)Bu(is)Pr][Cr(8)CdF(9)(O(2)CC(CH(3))(3))(18)].
• Analyzed measurements at varying magnetic fields, focusing on the critical field B(c) = 2.3 T.

Main Results:

• Observed a clear electronic energy level crossing, specifically an S = 0 --> S = 1 transition, at B(c) = 2.3 T.
• Detected a resonance-like dip in average positron asymmetry at the transition.
• Muon spin relaxation rate showed a sharp increase and a peak within the S = 1 regime.

Conclusions:

• The study provides the first observation of an electronic energy level crossing in an MNM using muon spin relaxation.
• Confirms that muon spin relaxation is a viable technique for probing electronic spin dynamics in MNMs.
• The findings offer new insights into the quantum behavior of molecular nanomagnets.