Vendredi 22 novembre 2019 à 11h00, Gabriele De Luca (University of Zurich, Switzerland) donnera un séminaire sur "Ultrathin oxide heterostructures : the impact of the interface"
Abstract :
Transition metal oxides (TMOs) are characterized by a richness of properties spanning from colossal magnetoresistance to high-temperature superconductivity due to the intricate nature of the metal-oxygen bond and the strong coupling between charge, lattice, spin and orbital degrees of freedom. In the last decades, inspired by the successful semiconductor-technology approach, many efforts have been devoted in refining the oxide-thin-film deposition techniques and their associated in-situ diagnostic tools with the aim to control the growth of TMOs down to a single atomic layer. A critical consequence of this pursued thickness reduction is the increasing influence of the interfaces/surfaces in determining the physical properties of the heterostructure under investigation.
To illustrate the significance of this scenario, I will briefly reexamine the prototypical LaAlO3/SrTiO3 conductive interface within the framework of the polar catastrophe. I will then discuss the complex interplay between thickness, strain, depolarizing field and resulting domain state in ultrathin ferroelectric heterostructures based on Pb(Zr0.2Ti0.8)O3 and BaTiO3. These results will be presented with a specific focus on second harmonic generation, a nonlinear optical tool that proved to be very efficient for studying the polar properties of these systems. Finally, I will introduce the insulating ferromagnet La2NiMnO6 (double perovskite) and how we investigated the evolution of its electronic and magnetic properties as a function of strain in the ultrathin limit.
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N. Strkalj*, GDL*, et al. Phys. Rev. Lett. 123, 147601 (2019)
