Nucleation processes of mixed-phase states are an intrinsic characteristic of first-order phase transitions, typically related to local symmetry breaking. Direct observation of emerging mixed-phase ...regions in materials showing a first-order metal-insulator transition (MIT) offers unique opportunities to uncover their driving mechanism. Using photoemission electron microscopy, we image the nanoscale formation and growth of insulating domains across the temperature-driven MIT in NdNiO
epitaxial thin films. Heteroepitaxy is found to strongly determine the nanoscale nature of the phase transition, inducing preferential formation of striped domains along the terraces of atomically flat stepped surfaces. We show that the distribution of transition temperatures is a local property, set by surface morphology and stable across multiple temperature cycles. Our data provide new insights into the MIT of heteroepitaxial nickelates and point to a rich, nanoscale phenomenology in this strongly correlated material.
In this review, we focus on the celebrated interface between two band insulators, LaAlO3 and SrTiO3, that was found to be conducting, superconducting, and to display a strong spin-orbit coupling. We ...discuss the formation of the 2-dimensional electron liquid at this interface, the particular electronic structure linked to the carrier confinement, the transport properties, and the signatures of magnetism. We then highlight distinctive characteristics of the superconducting regime, such as the electric field effect control of the carrier density, the unique tunability observed in this system, and the role of the electronic subband structure. Finally we compare the behavior of Tc
versus 2D doping with the dome-like behavior of the 3D bulk superconductivity observed in doped SrTiO3. This comparison reveals surprising differences when the Tc
behavior is analyzed in terms of the 3D carrier density for the interface and the bulk.
The polarization of PbTiO3/SrTiO3 superlattices is experimentally tuned from 0–60 μC/cm–2 and the transition temperature from room temperature to 1000 K while maintaining a perfect crystal structure ...and low leakage currents (see figure). A simple model based on Landau theory is developed as a guide for the straightforward production of samples with ferroelectric properties designed for particular applications.
Interface superconductivity Gariglio, S.; Gabay, M.; Mannhart, J. ...
Physica. C, Superconductivity,
07/2015, Volume:
514
Journal Article
Peer reviewed
Open access
•We discuss interfacial superconductivity, a field boosted by the discovery of the superconducting interface between LaAlO.•This system allows the electric field control and the on/off switching of ...the superconducting state.•We compare superconductivity at the interface and in bulk doped SrTiO.•We discuss the role of the interfacially induced Rashba type spin–orbit.•We briefly discuss superconductivity in cuprates, in electrical double layer transistor field effect experiments.•Recent observations of a high Tc in a monolayer of FeSe deposited on SrTiO3 are presented.
Low dimensional superconducting systems have been the subject of numerous studies for many years. In this article, we focus our attention on interfacial superconductivity, a field that has been boosted by the discovery of superconductivity at the interface between the two band insulators LaAlO3 and SrTiO3. We explore the properties of this amazing system that allows the electric field control and on/off switching of superconductivity. We discuss the similarities and differences between bulk doped SrTiO3 and the interface system and the possible role of the interfacially induced Rashba type spin–orbit. We also, more briefly, discuss interface superconductivity in cuprates, in electrical double layer transistor field effect experiments, and the recent observation of a high Tc in a monolayer of FeSe deposited on SrTiO3.
The physical mechanisms responsible for the formation of a two-dimensional electron gas at the interface between insulating SrTiO(3) and LaAlO(3) have remained a contentious subject since its ...discovery in 2004. Opinion is divided between an intrinsic mechanism involving the build-up of an internal electric potential due to the polar discontinuity at the interface between SrTiO(3) and LaAlO(3), and extrinsic mechanisms attributed to structural imperfections. Here we show that interface conductivity is also exhibited when the LaAlO(3) layer is diluted with SrTiO(3), and that the threshold thickness required to show conductivity scales inversely with the fraction of LaAlO(3) in this solid solution, and thereby also with the layer's formal polarization. These results can be best described in terms of the intrinsic polar-catastrophe model, hence providing the most compelling evidence, to date, in favour of this mechanism.
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