Evidence for a spinon Kondo effect in cobalt atoms on single-layer 1T-TaSe${}_2$

Abstract

Quantum spin liquids (QSLs) are highly entangled, disordered magnetic states that arise in frustrated Mott insulators and host exotic fractional excitations such as spinons and chargons. Despite being charge insulators some QSLs are predicted to exhibit gapless itinerant spinons that yield metallic behavior in the spin channel. We have deposited isolated magnetic atoms onto single-layer (SL) 1T-TaSe${}_2$, a gapless QSL candidate, to experimentally probe how itinerant spinons couple to impurity spin centers. Using scanning tunneling spectroscopy we observe the emergence of new, impurity-induced resonance peaks at the 1T-TaSe${}_2$ Hubbard band edges when cobalt adatoms are positioned to have maximal spatial overlap with the Hubbard band charge distribution. These resonance peaks disappear when the spatial overlap is reduced or when the magnetic impurities are replaced with non-magnetic impurities. Theoretical simulations using a modified Anderson impurity model integrated with a gapless quantum spin liquid show that these resonance peaks are consistent with a Kondo resonance induced by spinons combined with spinon-chargon binding effects that arise due to QSL gauge-field fluctuations.

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• Electronic Density of States of a $U\left(1\right)$ Quantum Spin Liquid with Spinon Fermi Surface. I. Orbital Magnetic Field Effects
• Nature of the unconventional heavy fermion Kondo state in monolayer CeSiI
• Electronic Density of States of a $U\left(1\right)$ Quantum Spin Liquid with Spinon Fermi Surface. II. Zeeman Magnetic Field Effects
• Charge-Neutral Electronic Excitations in Quantum Insulators
• Spectroscopic evidence for possible quantum spin liquid behavior in a two-dimensional Mott insulator
• Nature of metallic and insulating domains in the CDW system 1T-TaSe2
• Is spontaneous vortex generation in superconducting 4Hb-TaS${}_2$ from vison-vortex nucleation with ${\mathbb{Z}}_2$ topological order?
• Theory of quasiparticle interference in Kitaev quantum spin liquids
• Drag resistance mediated by quantum spin liquids
• Revealing spinons by proximity effect
• Local spin-flip transitions induced by magnetic quantum impurities in two-dimensional magnets
• Behavior under magnetic field of resonance at the edge of the upper Hubbard band in 1T-TaS2
• Tunneling spectroscopy of the spinon-Kondo effect in one-dimensional Mott insulators
• Topical review: the nature of the ground state and possibility of a quantum spin liquid in 1T metal dichalcogenides
• Detecting symmetry fractionalization in gapped quantum spin liquids by magnetic impurities
• Emergent quantum phenomena in two-dimensional 1T-TaS2
• Electrical probe of spin-spiral order in quantum spin Hall/spin-spiral magnet van der Waals heterostructures
• Spin liquid phase in the Hubbard model: Luttinger-Ward analysis of the slave-rotor formalism