Signatures of a Majorana-Fermi surface in the Kitaev magnet Ag3LiIr2O6

Abstract

Detecting Majorana fermions in experimental realizations of the Kitaev honeycomb model is often complicated by non-trivial interactions inherent to potential spin liquid candidates. In this work, we identify several distinct thermodynamic signatures of massive, itinerant Majorana fermions within the well-established analytical paradigm of Landau-Fermi liquid theory. We find a qualitative and quantitative agreement between the salient features of our Landau-Majorana liquid theory and the Kitaev spin liquid candidate Ag₃LiIr₂O₆. Our study presents strong evidence for a Fermi liquid-like ground state in the fundamental excitations of a honeycomb iridate, and opens new experimental avenues to detect itinerant Majorana fermions in condensed matter systems.

While Majorana excitations are often considered to be a cornerstone for proposed quantum devices, their experimental detection has proven to be a significant challenge. Here, the authors theoretically and experimentally demonstrate that the Kitaev candidate material Ag₃LiIr₂O₆ may support a Majorana-Fermi surface, which could potentially serve as a “smoking gun” for a quantum spin liquid ground state through the lens of specific heat data.