Magnetic molecular orbitals in MnSi.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Magnetism

Background:

• Magnetism is typically explained by models of interacting spins on magnetic ions.
• Proposals beyond the ionic picture are rare and lack direct experimental verification.
• Understanding magnetism in itinerant systems is crucial for developing new quantum materials.

Purpose of the Study:

• To investigate the fundamental magnetic units in the itinerant near-ferromagnet MnSi.
• To challenge the conventional ionic model of magnetism with experimental evidence.
• To explore the unexplored regime of spin waves in relation to molecular orbitals.

Main Methods:

• Inelastic neutron scattering experiments were performed on MnSi.
• Ab initio calculations were used to obtain magnetic Wannier orbitals.
• Experimental findings were corroborated with theoretical calculations.

Main Results:

• The fundamental magnetic units in MnSi are interconnected, extended molecular orbitals of three Mn atoms.
• This contrasts with the traditional model of individual magnetic ions.
• An unexplored regime of spin waves was identified where wavelengths approach molecular orbital dimensions.

Conclusions:

• The study provides a concrete example challenging the ionic picture of magnetism.
• The findings offer significant insights into the magnetism of MnSi.
• This work advances the understanding of magnetic quantum materials where symmetry, itinerancy, and correlations interact.