biostudies-literatureZhang XNational Science Foundation (NSF)United States-Israel Binational Science Foundation (BSF)e2202496119https://www.ebi.ac.uk/biostudies/studies/S-EPMC9304025biostudies-literatureUnknown119(29)Resistivity saturation is found on both superconducting and insulating sides of an "avoided" magnetic-field-tuned superconductor-to-insulator transition (H-SIT) in a two-dimensional In/InO<i>_x</i> composite, where the anomalous metallic behavior cuts off conductivity or resistivity divergence in the zero-temperature limit. The granular morphology of the material implies a system of Josephson junctions (JJs) with a broad distribution of Josephson coupling <i>E_J</i> and charging energy <i>E_C</i>, with an H-SIT determined by the competition between <i>E_J</i> and <i>E_C</i>. By virtue of self-duality across the true H-SIT, we invoke macroscopic quantum tunneling effects to explain the temperature-independent resistance where the "failed supProceedings of the National Academy of Sciences of the United States of AmericaAnomalous metals: From "failed superconductor" to "failed insulator".PMC93040252014098NSF-DMR-1808385Zhang XKapitulnik APalevski AfalseAnomalous metals: From "failed superconductor" to "failed insulator".Resistivity saturation is found on both superconducting and insulating sides of an "avoided" magnetic-field-tuned superconductor-to-insulator transition (H-SIT) in a two-dimensional In/InO<i>_x</i> composite, where the anomalous metallic behavior cuts off conductivity or resistivity divergence in the zero-temperature limit. The granular morphology of the material implies a system of Josephson junctions (JJs) with a broad distribution of Josephson coupling <i>E_J</i> and charging energy <i>E_C</i>, with an H-SIT determined by the competition between <i>E_J</i> and <i>E_C</i>. By virtue of self-duality across the true H-SIT, we invoke macroscopic quantum tunneling effects to explain the temperature-independent resistance where the "failed sup2022-01-01T00:00:00Z2022 Jul2025-04-04T20:33:04.171Z2025-04-04T20:33:04.171ZS-EPMC93040253585831310.1073/pnas.2202496119