Magnetic molecular orbitals in MnSi

Abstract

A large body of knowledge about magnetism is attained from models of interacting spins, which usually reside on magnetic ions. Proposals beyond the ionic picture are uncommon and seldom verified by direct observations in conjunction with microscopic theory. Here, using inelastic neutron scattering to study the itinerant near-ferromagnet MnSi, we find that the system's fundamental magnetic units are interconnected, extended molecular orbitals consisting of three Mn atoms each, rather than individual Mn atoms. This result is further corroborated by magnetic Wannier orbitals obtained by ab initio calculations. It contrasts the ionic picture with a concrete example, and presents a novel regime of the spin waves where the wavelength is comparable to the spatial extent of the molecular orbitals. Our discovery brings important insights into not only the magnetism of MnSi, but also a broad range of magnetic quantum materials where structural symmetry, electron itinerancy and correlations act in concert.

27 pages, 27 figures including supplemental; comments are welcome

References in corpus (10)

• Double crystallographic groups and their representations on the Bilbao Crystallographic Server
• Possible valence-bond condensation in the frustrated cluster magnet LiZn2Mo3O8
• The quantum origins of skyrmions and half-skyrmions in Cu2OSeO3
• Symmetry-enforced topological nodal planes at the Fermi surface of a chiral magnet
• Fate of partial order on the trillium and distorted windmill lattices
• Spin-orbit fluctuations in frustrated heavy-fermion metal LiV${}_2$O${}_4$
• Effective Hamiltonian of Three-orbital Hubbard Model on Pyrochlore Lattice: Application to LiV_2O_4
• From Atomic Semimetal to Topological Nontrivial Insulator
• A microscopic model for spiral ordering along (110) on the MnSi lattice
• Quasiparticle characteristics of the weakly ferromagnetic Hund's metal MnSi

Cited by in corpus (5)

• Spectral Evidence for Local-Moment Ferromagnetism in van der Waals Metals Fe${}_3$GaTe${}_2$ and Fe${}_3$GeTe${}_2$
• Spin-charge-lattice coupling across the charge density wave transition in a Kagome lattice antiferromagnet
• Dynamic Spin-Lattice Coupling and Statistical Interpretation for the Molecular-Like Excitations in Frustrated Pyrochlores
• Origin of the suppression of magnetic order in MnSi under hydrostatic pressure
• Enhanced Itinerant Ferromagnetism in Hole-doped Transition Metal Oxides: Beyond the Canonical Double Exchange Mechanism