DQMP Forum - Fine-tuning the Nickelate Phase Diagram - Advanced Scanning Transmission Electron Microscopy Applied to Rare-earth Nickelate Research

07.04.2020 13:00 – 14:30

Fine-tuning the Nickelate Phase Diagram
Jennifer Fowlie (group of Prof. Triscone)

The family of rare earth nickelates (RNiO3) display a rich plethora of physical properties including their famous metal-to-insulator transition that can be tuned with substitution of different rare earth cations, representing a bandwidth-mediation. Solid solutions of Nd1−xLaxNiO3 have provided an insight into an interesting region of the phase diagram - where the first order metal-to-insulator transition should be suppressed and exotic phenomena may be anticipated.
Here, Nd1−xLaxNiO3 was grown in thin film form. First of all, materials aspects of the growth of such solid solutions will be discussed. Then, a striking discontinuity in the metal-to-insulator phase transition versus x will be described along with various scenarios that may provide insight into this intriguing behaviour.
The possibility that the bulk rare earth nickelate phase diagram will finally be put forth.


Advanced Scanning Transmission Electron Microscopy Applied to Rare-earth Nickelate Research
Bernat Mundet (group of Prof. Triscone)

The development of aberration-corrected scanning transmission electron microscopy (STEM) represented a significant breakthrough in material science and physics research thanks to its possibility of acquiring images with sub-atomic resolution which are incoherent in nature, such that their contrast can be directly interpreted without need for simulations [1]. In addition, the probe and detector geometries allow the simultaneous measurement of complementary spectroscopic and imaging signals from the same crystal region [2].
In this presentation, I will first introduce the main components of the scanning transmission electron microscope, as well as the most common imaging and spectroscopic modes. In a second part, I will present two studies conducted on LaxNd1−xNiO3 solid solution thin films and NdNiO3/SmNiO3 superlattices, where I will show the possibilities offered by this technique to provide answers at the nanometric and atomic scales.
[1] P. D. Nellist, S. J. Pennycook, Ultramicroscopy 78, 111 (1999)
[2] S.Pennycook, P.Nellist, Scanning Transmission Electron Microscopy (Springer, New York, 2011)


Forum Committee: C. Lichtensteiger, N. Ubrig, A. Tamai (March 2, 2020)

Lieu

During this major health crisis, we have decided to maintain the DQMP Forum, using Zoom. Everyone is welcome to connect to the next Forum:

Zoom Meeting, Meeting ID: 582 067 708
https://unige.zoom.us/j/582067708

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