Magnetostriction-Driven Muon Localization in an Antiferromagnetic Oxide

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Magnetostriction arises from the interplay between magnetic and elastic properties in materials.
• Understanding the behavior of implanted muons is crucial for probing local magnetic environments.
• Manganese oxide (MnO) exhibits a cubic rocksalt antiferromagnetic structure with a Néel temperature (T_{N}) of 118 K.

Purpose of the Study:

• To investigate the role of magnetostriction in determining the preferred site of implanted muons in magnetic materials.
• To explain the observed muon data in MnO, particularly the site switching phenomenon around the magnetic phase transition.
• To demonstrate the broader applicability of these findings to other magnetic oxide systems.

Main Methods:

• First-principles simulations utilizing Hubbard-corrected density-functional theory (DFT+U).
• Molecular dynamics simulations to capture the dynamic behavior of the system.
• Analysis of magnetostriction-driven structural distortions in MnO below its Néel temperature.

Main Results:

• Magnetostriction significantly influences the energetically favorable site for implanted muons in MnO.
• A transition from delocalized muon behavior above T_{N} to localized sites below T_{N} due to rhombohedral distortion.
• Simulations align with experimental data, resolving a long-standing puzzle in MnO muon studies.

Conclusions:

• Magnetostriction, despite its small energy contribution, plays a critical role in muon site determination in magnetic materials.
• The study resolves discrepancies in previous MnO muon data by accounting for magnetostriction-induced structural changes.
• The findings have implications for understanding muon behavior and material properties in a wide range of magnetic oxides.