PhD position in oxide thin film growth - Nanoscale electrostatic control in ferroelectric thin films through lattice chemistry

The Nonlinear optics for Epitaxial growth of Advanced Thin films (NEAT) laboratory within the institute of Multifunctional Ferroic Materials in the Materials Department is seeking for PhD candidates. We work on the epitaxial deposition of functional oxide thin films using pulsed laser deposition. We use in-situ diagnostic tools during the growth process to advance the design of technologically relevant oxide thin films. In particular, the combination of state of the art non-linear optics monitoring and electron spectroscopy in situ allows investigating the dynamics of the functional properties as we grow the films from the very first unit cell. We are interested in studying the evolution of physical properties of epitaxial thin films in the ultrathin regime and in the investigation of interface related phenomena in multilayers.

Ferroelectric transition metal oxides offer a wide range of functionalities and in thin-film form, their anticipated applications include low energy-consuming electric-field-controllable non-volatile memory elements with high information density. The recent progress in controlling the electrostatic and elastic boundary conditions in thin film superlattices, manipulating the physical properties of the interfaces, allowed the design of more complex and functional electric dipole orderings such as polar vortices or skyrmions, and thus, expanded the field of applications of ferroelectric materials. In contrast to the depolarizing-field tuning approach, an increasing number of studies has been reporting the impact of spontaneously forming charged off-stoichiometric surface layers on the polarization state of ferroelectric thin films.The PhD project unites our leading international expertise in oxide thin film growth and nonlinear laser spectroscopy. We will pioneer the use of charged surface layers as polarizing sheets in our functional heterostructures and establish new routes for nanoscale electrostatic control in ferroelectric thin films through lattice chemistry.

The goal of the doctoral project is to explore the potential of the chemistry of the lattice (charged off-stoichiometric layers, chemical variation in layered compounds, etc...) as an additional degree of freedom to act on the ferroelectric order in striking contrast with the conventional depolarizing-field tuning strategy. Using our unique capacity to engineer oxide thin films interfaces with atomic precision, combined with our state of the art non invasive optical probe of polarization in thin films, we will advance the exploitation of the surface chemistry in oxide ferroelectric thin films. Additional structural and functional characterization tools will be employed (scanning probe microscopy, X-ray diffraction, transmission electron microscopy and many more...)

We will set the foundation for alternative design routes for epitaxial oxide multilayers with naturally forming, polarizing electrostatic boundary conditions, pushing forward the engineering of technology-relevant chiral polar, magnetic and magnetoelectric textures.

Our in-situ monitoring capacity of polarization during the growth and now, during optical poling is unique in the world. This PhD project thus offers plenty of room for exciting physics and groundbreaking discoveries, and our lab has exactly the expertise to acquire these. Our intense collaboration with experts in the field of electron microscoy, magnetic characterization and nitrogen vacancy scanning electrometry enables a multiscale apporach.

Candidates will join our international NEAT research team of highly motivated PhD and Master students and use our workplaces for thin films growth and characterization with nonlinear laser spectroscopy. They will design and set up their own experiment and are never afraid to tear it down and try a new approach, should this become necessary. Despite the focus on thin-film growth experiments, the involvement of other experimental techniques and in-depth discussion with theoretical groups are likely.

• You have a masters degree in Physics or Materials Science
• You have basic education in condensed-matter physics
• You like to work on complex problems with an urge to understand phenomena at their roots
• You are highly motivated, self-organized, creative, and used to thinking sideways
• You are a team player who likes to work in an interdisciplinary environment at the interface between optics and condensed-matter physics
• You are communicative with the ability to explain your project to non-specialists in simple words

• Outstanding lab facilities with pulsed laser depostion chambers, femtosecond and nanosecond laser systems
• An international environment of mutually supportive people
• A flat hierarchy: everyone's opinion weighs the same in scientific discussions
• Excellent working conditions and an internationally competitive salary
• Support for attending international conferences and workshops
• An extensive network of scientific collaborators
• Access to the excellent technological infrastructure of ETH Zurich
• Administrative support