Probing Quantum Spin Liquids in the Kitaev model through spin current measurements

The Kitaev model is classified among an unconventional category of two-dimensional spin models characterized by direction-dependent interactions that facilitate Quantum Spin Liquid (QSL) states. Although the Kitaev model has resulted in extensive theoretical predictions, direct observations of QSL phases necessitate intricate experimental procedures due to the lack of any magnetic order. In this study, we introduce the theoretical analysis of an innovative method to detect the QSL characteristics of magnetic models by examining the spin current injected into the Kitaev model from an adjacent normal metal. We provide a comprehensive development of the injected spin current, identifying distinctive features that delineate the spin transport by Majorana fermions. The findings are compared with typical ferromagnetic junctions, for which the spin carries are provided by magnons, and leveraging insights from spintronics and quantum magnetism, we propose a novel mechanism to verify the existence of QSL states.