Direct observation of surface bandgap shrinkage and negative electronic compressibility in SrTiO3
This study utilizes ARPES and DFT calculations to demonstrate that UV-induced electron doping in SrTiO3 causes a significant surface bandgap shrinkage and a counterintuitive valence band shift indicative of negative electronic compressibility, distinguishing it from KTaO3 and highlighting its potential for advanced oxide electronic and energy storage applications.