Forum DQMP - SmNiO3/NdNiO3 superlattices (Claribel Dominguez from group of Prof. Triscone) & Cell front roughness: exploring the link between cell-cell interactions and colony (Guillaume Rapin from group of Prof. Paruch)

29.05.2018 13:00 – 14:00

SmNiO3/NdNiO3 superlattices
Claribel Dominguez (group of Prof. Triscone)

Rare earth nickelates RNiO3 (R¹La) display a metal to insulator transition (MIT) accompanied
by an unusual antiferromagnetic order at TNéel≤TMI. Bulk NdNiO3 (NNO) shows TNéel=TMI,
whereas for SmNiO3 (SNO) TMI>TNéel. Notably, TNéel and TMI are function of the Ni-O-Ni bond
angle which depends on the rare earth size and subtle changes in this angle can strongly modify
the electronic behavior of the system.
Here, we adopt a new strategy to study the evolution of structural distortions in RNiO3-based
heterostructures and their impact on the electronic properties by growing [n(SNO)/n(NNO)]m
superlattices (SLs). We have found that the thickness of the individual SNO and NNO layers
controls the TMI and TNéel of the whole system. For thicker SLs periods two separate MITs
corresponding to those of the individual SNO and NNO layers are observed. However, the two
separate MITs merge into a single one as the SL period is reduced. TMI and TNéel relation will
also be investigated.


Cell front roughness: exploring the link between cell-cell interactions and colony
geometry and dynamics
Guillaume Rapin (group of Prof. Paruch)

The geometric properties and dynamics of various physical interfaces are governed by the
competition between elasticity and the potential energy landscape [1]. The equilibrium
configuration shows a self-affine roughening and a non-linear response to driving forces, with
characteristic scaling exponents depending on the underlying interactions.

This statistical physics approach has been successfully applied to biological interfaces such as
cell fronts, with local mapping of displacements and forces during proliferation [2], and studies
demonstrating the power-law growth of cell front roughness [3]. In these interfaces, a key goal
is to understand how the various interactions influence the geometric properties and dynamics
of the interface [4].

We address this question via comparative studies of the roughness and dynamics of
proliferating cell fronts. We observe a power-law growth of the roughness with different regimes,
followed by a slower roughness evolution at high length scales. The time evolution of the front
geometry and motion show non-linear behaviour. These in-vitro observations are compared with
numerical simulations.

1. Barabasi and Stanley. Fractal Concepts in Surface Growth. Cambridge University Press, New York, USA, (1995)
2. Trepat et al., Nat. Phys. 5, 426 (2009) ; Angelini et al., PNAS 108, 4714 (2011)
3. Huergo et al., Phys. Rev. E 82, 31903 (2010); Huergo et al., Phys. Rev. E 85, 011918 (2012)
4. Huergo et al., Phys. Rev. E 90, 022706 (2014); Moglia et al., Phys. Rev. E 94, 052139 (2016)


Forum Committee: C. Lichtensteiger, N. Ubrig, A. Tamai (23.05.2018)

Lieu

Bâtiment: Ecole de Physique

Auditoire Stückelberg
Ecole de physique

entrée libre