Research: Kondo screening in a Majorana metal

Kondo impurities provide a nontrivial probe to unravel the character of the excitations of a quantum spin liquid. In the S = 1/2 Kitaev model on the honeycomb lattice, Kondo impurities embedded in the spin-liquid host can be screened by semimetallic Majorana fermions via gauge-flux binding. Experiments on the Kitaev honeycomb material α-RuCl₃, doped with dilute Cr3+ (S = 3/2) impurities, have now shown signatures of metallic-like Kondo screening at intermediate temperatures. Multiple thermodynamic observables feature logarithmic temperature dependencies, a hallmark of a metallic Kondo effect. Concurrently, the linear coefficient of the magnetic specific heat is large in the same temperature regime, indicating the presence of a host Majorana metal. This observation opens new avenues for exploring uncharted Kondo physics in insulating quantum magnets.

S. Lee, Y. S. Choi, S.-H. Do, W. Lee, C. H. Lee, M. Lee, M. Vojta, C. N. Wang, H. Luetkens, Z. Guguchia, K.-Y. Choi,
Kondo screening in a Majorana metal,
Nat. Commun. 14, 7405 (2023) (arXiv)