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Séminaire - Gertjan Koster

Mercredi 13 novembre 2019 à 14h00, Gertjan Koster (University of Twente, Enschede, the Netherlands ) donnera un séminaire sur "Controlled properties in oxide heterostructures by interface-engineered oxygen octahedral coupling "
Abstract :
In this presentation I will discuss examples of manipulation of magnetic properties. We demonstrated how to manipulate magnetic and electronic anisotropic properties in manganite heterostructures by engineering the oxygen network on the unit-cell level. The strong oxygen octahedral coupling is found to transfer the octahedral rotation present in the NdGaO3 (NGO) substrate to the La2/3Sr1/3MnO3 (LSMO) film in the interface region. This causes an unexpected realignment of the magnetic easy axis along the short axis of the LSMO unit cell as well as the presence of a giant anisotropic transport in these ultrathin LSMO films. As a result, we possess control of the lateral magnetic and electronic anisotropies by atomic scale design of the oxygen octahedral rotation [1]
Similar manipulation can be achieved in other material systems, even when more technical substrates (Si) are used : The critical temperature of the metal-to-insulator transition in SmNiO3 can be tuned by choosing a spacing layer with different amounts of octahedral tilts in a superlattice configuration. By intercalating the prototype SmNiO3 target material with a tilt-control layer, we cause the system to change the natural amplitude of a given rotation mode without affecting the interactions. In contrast to strain and dimensionality engineering, our method enables a continuous fine-tuning of the materials properties [2]. In addition, I will briefly discuss the latest results of nickelate thin films grown on STO buffered Si.

[1] Liao et al., Nat Mater 15, 425 (2016)
[2] Liao et al., PNAS 115, 9515 (2018)


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