Superconductivity and novel electron transport of elemental superconductors under pressure

Superconductivity stands as the initial macroscopic quantum phenomenon unearthed by mankind. In the century-old history of superconductivity research, several novel transport phenomena have emerged, including the intermediate anomalous metallic state (AMS) in the superconductor-insulator transition at ultralow temperatures and the metal-bosonic insulator-superconductor transition (MIST) near the critical temperature (T_c). These types of behavior, primarily observed in disordered or chemically doped low-dimensional systems, raise intriguing questions about their universality and the underlying physics. In recent work, we found experimental evidence for a 3D AMS in highly compressed titanium at strong magnetic fields. We observed AMS characteristics, including low-temperature saturation resistance and giant positive magnetoresistance. This discovery offers a fresh platform to explore the long-standing enigmatic physics of AMS. Moreover, we found a magnetic field-induced MIST in highly compressed sulfur, marked by a resistance peak prior to superconductivity. The findings on compressed sulfur, a well-established elemental superconductor, suggest the possibility of unveiling diverse electronic and transport phenomena in putatively simple systems and open avenues for further delving into the essence of anomalous transport mechanisms in condensed matter. In Addition, we observed in scandium a superconducting temperature of 37.6 K at 243 GPa, the current record high T_c for an elemental superconductor. These results further advance our understanding superconductivity under extreme conditions.