Hard x-ray photoelectron spectroscopy of tunable oxide interfaces
Martina Müller, Patrick Lömker, Paul Rosenberger, Mai Hussein Hamed, David N. Mueller, R. Heinen, Thomas Szyjka, Lutz Baumgarten
Abstract
The tunability of the oxygen content in complex oxides and heterostructures has emerged as a key to designing their physical functionalities. Controlling the interface reactivity by redox reactions provides a powerful means to deliberately set distinct oxide phases and emerging properties. We present routes on how to control oxygen-driven redox mechanisms in ultrathin ferro(i)magnetic and ferroelectric oxide films and across oxide interfaces. We address the growth and control of metastable EuO oxide phases, the control of phase transitions of binary Fe oxides by oxygen migration, the in operando determination of NiFe2O4/SrTiO3 interface band alignments, as well as the role of interfacial oxide exchange in ferroelectric HfO2-based capacitors—uncovered by the unique capabilities of photoelectron spectroscopy and, in particular, using hard x-rays.