Giant and anisotropic many-body spin-orbit tunability in a strongly correlated kagome magnet

TL;DR

This study uncovers the giant, anisotropic, many-body spin-orbit effects in a strongly correlated kagome magnet, demonstrating how vector magnetic fields can control electronic nematicity and topological phases.

Contribution

It reveals the strong coupling between vector magnetic fields and many-body electronic states in a kagome ferromagnet, showing tunable spin-orbit phenomena and emergent correlated topological phases.

Findings

Giant nematic energy shifts driven by magnetization

Spontaneous nematicity indicating electron correlation

Magnetic field control of electronic symmetry and topological states

Abstract

Owing to the unusual geometry of kagome lattices-lattices made of corner-sharing triangles-their electrons are useful for studying the physics of frustrated, correlated and topological quantum electronic states. In the presence of strong spin-orbit coupling, the magnetic and electronic structures of kagome lattices are further entangled, which can lead to hitherto unknown spin-orbit phenomena. Here we use a combination of vector-magnetic-field capability and scanning tunnelling microscopy to elucidate the spin-orbit nature of the kagome ferromagnet Fe3Sn2 and explore the associated exotic correlated phenomena. We discover that a many-body electronic state from the kagome lattice couples strongly to the vector field with three-dimensional anisotropy, exhibiting a magnetization-driven giant nematic (two-fold-symmetric) energy shift. Probing the fermionic quasi-particle interference reveals consistent spontaneous nematicity-a clear indication of electron correlation-and vector magnetization is capable of altering this state, thus controlling the many-body electronic symmetry. These spin-driven giant electronic responses go well beyond Zeeman physics and point to the realization of an underlying correlated magnetic topological phase. The tunability of this kagome magnet reveals a strong interplay between an externally applied field, electronic excitations and nematicity, providing new ways of controlling spin-orbit properties and exploring emergent phenomena in topological or quantum materials.