Jorge Íñiguez's research

Welcome!

I am a theoretical and computational physicist working at the Luxembourg Institute of Science and Technology, and also an affiliated professor of Physics at the University of Luxembourg. I use various theoretical and simulation methods to study materials properties. Most of my work has to do with applications of Density Functional Theory, an approach that offers unique insight into the microscopic origin of the most diverse phenomena, as well as the predictive power necessary for the design of novel systems optimized for applications. My current research focuses on functional oxides, especially ferroelectrics and magnetoelectric multiferroics. I also develop new tools for large-scale simulations within the SCALE-UP project.


Job Opportunities

We often have PhD and post-doc positions available. If you are interested in what we do, and have a good and suitable CV, I encourage you to contact me at any time. In particular, if you are a student looking for a PhD position, please send an academic record as complete as possible.

On occasion, we are willing to sponsor grant applications of excellent candidates. This may be a prestigious way to join us for your PhD (e.g., through the AFR scheme of the Luxembourg National Research Fund) or post-doc work (e.g., through the Marie Skłodowska-Curie program of the European Commission). Feel free to contact me if you think you are a good candidate to get one of those!

Latest highlights

The (many) antiferroelectrics in our midst (?)

Two years ago, Hugo Aramberri and I set up to discover new antiferroelectric materials using a high-throughput computational approach. Antiferroelectrics are close relatives of ferroelectrics, but with local dielectric dipoles (which result from the relative displacement of cations and anions) being antialigned (and thus canceling out) instead of aligned (which would result in a net macroscopic polarization). In particular, we looked at the family of perovskite oxides, which includes quite a few ferroelectrics (e.g., BaTiO3, PbTiO3) but very few antiferroelectrics (e.g., PbZrO3). Would we be able to discover previously unnoticed antiferroelectric perovskites and, in passing, figure out the reasons for the ferro over antiferro prevalence? As it often happens, this journey took us to an unexpected destination, as the best (only) new antiferroelectric candidate we were able to identify (CsVO3) turned out to yield a non-perovksite structure when we investigated its ground state. Indeed, we then discovered that this compound (as well as RbVO3 and the better studied KVO3) display a lattice sometimes called pyroxene-like due to its similarities with the very abundant and well-know pyroxene minerals. Most interestingly, pyroxene structures feature MO4 tetrahedra (where M can be something like Si or a metal atom) that are asymmetric by construction, thus presenting a permanent electric dipole. In normal conditions, such dipoles are antialigned, but we predicted that it is possible to apply an electric field to make them parallel and access a ferroelectric-like state. Hence, KVO3 and the other vanadates we looked at are antiferroelectric; and, most importantly, we have good reasons to believe that essentially all pyroxenes are antiferroelectric candidates! (Check out the details in Aramberri and Íñiguez, Comm. Mats. 1, 52 (2020).) Hence, antiferroelectrics -- relatively rare and unique materials that are promising for e.g. energy applications -- might be hiding all around, and we might be able to discover many more by looking at some very old minerals in a new light!


Let there be electric skyrmions!

Magnetic skyrmions are mesmerizing spin structures of unique topology and particle-like properties. Can there be an electric analogue, with electric dipoles instead of spins? Scientists have been pondering this question for a few years, and some interesting theoretical proposals have appeared. However, the strategies suggested so far to stabilize skyrmion-like electric states are difficult to implement experimentally and by-construction preclude some of the most desirable properties of skyrmions, e.g. their mobility. The situation has turned around this year. In a second-principles investigation led by M.A.P. Gonçalves (LIST), and with collaborators J. Junquera and P. García-Fernández (Cantabria), we have shown it is possible to harness the non-trivial structure of the ferroelectric domain walls of PbTiO3 to create skyrmion bubbles by simply writing column-like nano-domains in an homogeneously polarized matrix [Gonçalves et al., Science Advances 5, eaau7023 (2019)]. Further, we find that these bubbles undergo topological and isotopological transitions when subject to external fields or heating, offering us a great deal of control. But that's not all: Most importantly, together with collaborators in Berkeley, Penn State and Cornell, we have been able to prove experimentally that such skyrmion bubbles can be stabilized at ambient conditions in PbTiO3-based heterostructures! [Das et al., Nature 568, 368 (2019)] While many challenges lay ahead (how to move the bubble domains, and thus the skyrmions, in a controlled way; how to switch their chirality), these works constitute a major breakthrough towards the obtention and manipulation of topological structures in strong ferroelectric materials, and effectively inaugurate a field that promises to be as exciting as it gets.