The mighty “nothing”: Shaping (defect) functionalities of quantum oxides

In oxide materials science, the „nothing” is mighty: The key to shaping the physical functionalities of oxide quantum materials and heterostructures lies in the tunability of their oxygen sublattice and, in particular, their defect structure. Initiating or suppressing oxygen migration or redox reactions is an effective means to create targeted oxide phases and unique material properties in confined systems. But what mechanisms govern oxygen-driven redox mechanisms in ultrathin oxide films and at oxide interfaces, and how can they ultimately be controlled at the nanometer scale? We will elucidate how the control of metastable phases and reversible phase transitions leads to an unprecedented versatility to tune electronic conductivity, ferro(i)magnetic and ferroelectric properties at will - uncovered by the compelling capabilities of photon-based electron spectroscopy techniques to explore quantum materials.