Evidence of a weakly-correlated Majorana liquid in the Kitaev magnet Ag3LiIr2O6

Kitaev magnets have gained a huge amount of interest in recent years due to the possibility of such materials hosting a highly-entangled quantum spin liquid (QSL) ground state. Such materials are characterized by a honeycomb lattice structure and can be analytically solved by mapping the localized spins into itinerant and localized Majorana excitations. Interestingly, recent experiments and numerics have shown that, within a finite-temperature range, the QSL near the "pure" Kitaev limit yields an exotic, metal-like phase with finite Sommerfeld coefficient. In this work, we describe the apparent Sommerfeld coefficient and exotic T-dependence in the specific heat of Ag3LiIr2O6 via a Landau-Fermi liquid theory of itinerant Majorana-like quasiparticles. By considering the effects of interaction on the statistical energy of these Majorana quasiparticles, the resulting specific heat is found to be dominated by a quadratic-temperature dependence with a strong non-analytic contribution, in agreement with present experiments on the silver-lithium iridate at zero and finite external magnetic field.