Vacancy-driven multichannel Kondo physics in topological quantum material IrO2.

Metal physics beyond the Landau Fermi liquid paradigm is a central topic in contemporary condensed matter science. Its connection with unconventional superconductivity is experimentally well established but the conditions under which these enigmatic metals can form has remained perplexing. The routes proposed towards strange metal formation, which includes the multichannel Kondo effect, generally require rather special conditions or fine-tuning. Here we report the observation of robust vacancy-driven orbital two-channel Kondo behavior which occurs without fine-tuning, in paramagnetic IrO2 nanowires possessing the rutile structure. We further demonstrate tunability of this unconventional state to its Fermi-liquid counterpart within the rutile structure through a complementary analysis of antiferromagnetic RuO2 nanowires. Our findings establish the inherent occurrence of non-Fermi liquid physics in a class of topological quantum materials, with implications for fundamental research and potential quantum device applications.