New projects & Milestones

Scientific highlights

• Discovery of the photoflexoelectric effect and report of its large magnitude in halide perovskites, one of the most important families of photovoltaic materials at the moment. The research is the result of a large collaboration involving ICN2, ICMAB and several institutions in China. This work, first-authored by Longlong Shu (Nanchang University) and last-authored by G. Catalan, was published in Nature Materials).
• First quantitative measurement of the internal mechanical properties of purely ferroelectric (non ferroelastic) domain walls, showing that they are always softer than the domains they separate. We think this work may mark the start of a new area of research, namely “domain wall nanomechanics”. The paper, first-authored by Christina Stefani (PhD Student at ICN2) and last-authored by G. Catalan, was published in Physical Review X.

Projects

We have obtained two national projects from the “Programa Estatal de I+D+i” (250k€+120k€), supported by two PhD Student grants from the FPI programme, to study the physics of oxide membranes and physical chemistry of ferroelectric surfaces. Watch this space for future progress in this area.

Remarkably, we have obtained a FET-Open Project ranked in the first place of its call, in collaboration with several other leading research institutes in Europe, in order to study topological structures (domain walls etc.) in antiferroic materials, including antiferroelectric and antiferromagnetic systems. The project, called TSAR (Topological Solitons in Antiferroics) has been awarded and will start in May 2021.

Advanced AFM lab

The ON group nanoscale research exploits the capabilities of atomic force microscopy to measure and map surface properties, including electromechanics. Under a piezoresponse force microscope, many different physical phenomena can lead to measurable nanoscale electromechanic responses, making quantification of piezoresponse a big deal. Progress towards correct quantification of piezoelectric responses at the nanoscale in semiconductor piezoelectrics have been done by calibrating the influence of Schottky barriers at the tip sample electromechanical coupling (H. Lozano., Nanotechnology 2020).

AFM studies are complemented with synchrotron-based XPS measurements to characterize the electrochemistry of ferroelectric surfaces under local applied electric fields in ambient conditions. Current on-going projects and some beam-time at CIRCE in July 2020 have allowed us to study the dynamics of screening of ferroelectric surfaces at the ferroelectric to paraelectric phase transition.