Structurally triggered metal-­‐insulator transition in rare-earth nickelates - Prof. Philippe Ghosez (Belgium)

13.07.2017 11:30 – 12:30

Rare-earth nickelates form a very intriguing series of ABO3 perovskite oxides, which except for LaNiO3, exhibit on cooling a sharp metal-­‐insulator electronic phase transition, a concurrent structural phase transition from Pbnm to P21/n symmetry and a magnetic phase transition toward an unusual E’-­‐type antiferromagnetic spin order. Although these compounds reveal appealing for various applications, their full exploitation is still hampered by the lack of global understanding of their different phase transitions. Here, I will first assess the ability of first-­‐principles calculations within the DFT+U formalism to describe simultaneously the structural, dynamical, electronic and magnetic properties of rare-­‐earth nickelates and briefly discuss these properties. Then, I will address the origin of the metal-­‐insulator transition. I will show from first-­‐principles calculations that it corresponds in fact to a structurally triggered phase transition1, highlighting at the same time a first concrete example of such a kind of phase transition in simple perovskites. The origin of this unusual mechanism will be traced back in the electronic and magnetic properties. I will illustrate that these findings are not limited to nickelates but remain also relevant in the discus-­‐sion of other perovskite series like ferrites and manganites.
This work was done in close collaboration with Alain Mercy, Jordan Bieder, Jorge Iñiguez, Yajun Zhang, He Xu, Marcus Schmitt and Eric Bousquet. The research has been partly supported by the PDR project Hit4FiT from F.R.S-­‐FNRS and the ARC project AIMED from University of Liège.
References:
1. A. Mercy, J. Bieder, J. Iniguez and Ph. Ghosez, Structurally triggered metal-­‐insulator transition
2. in rare earth nickelates, unpublished.

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Bâtiment: Ecole de Physique

MaNEP

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