Nirvana Caballero

Nirvana Caballero
University of Geneva | UNIGE

PhD in Physics
Postdoctoral researcher-Giamarchi's group and Paruch Lab, Teaching assistant in Phase Transitions, University of Geneva

About

24
Publications
1,944
Reads
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136
Citations
Citations since 2017
20 Research Items
120 Citations
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Introduction
I am a theoretical physicist. My research interests involve the collective behavior of disordered systems, non-equilibrium dynamics, and phase transitions. I develop and use advanced analytical and numerical techniques to treat the equilibrium and non-equilibrium dynamics of complex systems. I use high-performance computing techniques to tackle problems in close collaboration with experimentalists in Physics and Biology. More in: nirvanacaballero.org
Additional affiliations
September 2018 - present
University of Geneva
Position
  • PostDoc Position

Publications

Publications (24)
Preprint
Full-text available
The theory of disordered elastic systems is one of the most powerful frameworks to asses the physics of multiple systems that span from ferromagnets to migrating biological cells. In this formalism, one assumes that the system can be described with a displacement field. This field can represent an interface position, the deformation of a vortex lat...
Preprint
Full-text available
We present a field theory to describe the composition of a surface spontaneously exchanging matter with its bulk environment. By only assuming matter conservation in the system, we show with extensive numerical simulations that, depending on the matter exchange rates, a complex patterned composition distribution emerges in the surface. For one-dime...
Article
Full-text available
Elastic interfaces display scale-invariant geometrical fluctuations at sufficiently large lengthscales. Their asymptotic static roughness then follows a power-law behavior, whose associated exponent provides a robust signature of the universality class to which they belong. The associated prefactor has instead a nonuniversal amplitude fixed by the...
Article
Full-text available
Understanding and controlling the motion, stability, and equilibrium configuration of ferroelectric domain walls is key for their integration into potential nanoelectronic applications, such as ferroelectric racetrack memories. Using piezoresponse force microscopy, we analyze the growth and roughness of ferroelectric domains in epitaxial thin film...
Preprint
Full-text available
Understanding and controlling the motion, stability, and equilibrium configuration of ferroelectric domain walls is key for their integration into potential nanoelectronics applications, such as ferroelectric racetrack memories. Using piezoresponse force microscopy we analyse the growth and roughness of ferroelectric domains in epitaxial thin film...
Preprint
Full-text available
We compute numerically the roughness of a one-dimensional elastic interface subjected to both thermal fluctuations and a quenched disorder with a finite correlation length. We evidence the existence of a novel power-law regime, at short lengthscales, resulting from the microscopic interplay between thermal fluctuations and disorder. We determine th...
Article
Full-text available
Recent experiments show striking unexpected features when alternating square magnetic field pulses are applied to ferromagnetic samples: domains show area reduction and domains walls change their roughness. We explain these phenomena with a simple scalar-field model, using a numerical protocol that mimics the experimental one. For a bubble and a st...
Article
Full-text available
Juxtacellular interactions play an essential but still not fully understood role in both normal tissue development and tumour invasion. Using proliferating cell fronts as a model system, we explore the effects of cell–cell interactions on the geometry and dynamics of these one-dimensional biological interfaces. We observe two distinct scaling regim...
Article
Full-text available
Ferroelectric materials provide a useful model system to explore the jerky, highly nonlinear dynamics of elastic interfaces in disordered media. The distribution of nanoscale switching event sizes is studied in two Pb(Zr0.2Ti0.8)O3 thin films with different disorder landscapes using piezoresponse force microscopy. While the switching event statisti...
Article
Full-text available
Domain-wall dynamics and spatial fluctuations are closely related to each other and to universal features of disordered systems. Experimentally measured roughness exponents characterizing spatial fluctuations have been reported for magnetic thin films, with values generally different from those predicted by the equilibrium, depinning and thermal re...
Preprint
Full-text available
Juxtacellular interactions play an essential but still not fully understood role in both normal tissue development and tumour invasion. Using proliferating cell fronts as a model system, we explore the effects of cell-cell interactions on the geometry and dynamics of these one-dimensional biological interfaces. We observe two distinct scaling regim...
Preprint
Full-text available
Recent experiments show striking unexpected features when alternating square magnetic field pulses are applied to ferromagnetic samples: domains show area reduction and domains walls change their roughness. We explain these phenomena with a simple scalar-field model, using a numerical protocol that mimics the experimental one. For a bubble and a st...
Article
Full-text available
Controlling interfaces is highly relevant from a technological point of view. However, their rich and complex behavior makes them very difficult to describe theoretically, and hence to predict. In this work, we establish a procedure to connect two levels of descriptions of interfaces: for a bulk description, we consider a two-dimensional Ginzburg-L...
Preprint
Full-text available
Controlling interfaces is highly relevant from a technological point of view. However, their rich and complex behavior makes them very difficult to describe theoretically, and hence to predict. In this work, we establish a procedure to connect two levels of descriptions of interfaces: for a bulk description, we consider a two-dimensional Ginzburg-L...
Preprint
Full-text available
Along with experiments, numerical simulations are key to gaining insight into the underlying mechanisms governing domain wall motion in thin ferromagnetic systems. However, a direct comparison between numerical simulation of model systems and experimental results still represents a great challenge. Here, we present a tuned Ginzburg–Landau model to...
Article
Full-text available
Magnetic domain wall motion is at the heart of new magneto-electronic technologies and hence the need for a deeper understanding of domain wall dynamics in magnetic systems. In this context, numerical simulations using simple models can capture the main ingredients responsible for the complex observed domain wall behavior. We present a scalar-field...
Article
Family of compounds CBr$_n$Cl$_{4-n}$ has been proven helpful in unraveling microscopic mechanisms responsible of glassy behavior. Some of the family members show translational ordered phases with minimal disorder which appears to reveal glassy features, thus deserving special attention in the search for universal glass anomalies. In this work, we...
Article
Full-text available
The family of compounds CBrnCl4−n has been proven helpful in unraveling microscopic mechanisms responsible for glassy behavior. Some of the family members show translational ordered phases with minimal disorder which appears to reveal glassy features, thus deserving special attention in the search for universal glass anomalies. In this work, we stu...
Article
Full-text available
Magnetic field driven domain wall velocities in [Co/Ni] based multilayers thin films have been measured using polar magneto-optic Kerr effect microscopy. The low field results are shown to be consistent with the universal creep regime of domain wall motion, characterized by a stretched exponential growth of the velocity with the inverse of the appl...
Article
Full-text available
Carbon tetrachloride (CCl4) is one of the simplest compounds having a translationally stable monoclinic phase while exhibiting a rich rotational dynamics below 226 K. Recent nuclear quadrupolar resonance (NQR) experiments revealed that the dynamics of CCl4 is similar to that of the other members of the isostructural series CBrnCl4-n, suggesting tha...
Article
We present a detailed analysis of the molecular kinetics of CHCl$_3$ in a range of temperatures covering the solid and liquid phases. Using nuclear quadrupolar resonance we determine the relaxation times for the molecular rotations in solid at pre-melting conditions. Molecular dynamics simulations are used to characterize the rotational dynamics in...
Article
We present a molecular dynamics study of the liquid and plastic crystalline phases of CCl$_3$Br. We investigated the short-range orientational order using a recently developed classification method and we found that both phases behave in a very similar way. The only differences occur at very short molecular separations, which are shown to be very r...

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Projects (3)
Project
Controlling interfaces is highly relevant from a technological point of view. Their rich and complex behavior makes them very difficult to describe theoretically, and hence to predict. We connect different levels of descriptions of interfaces to decode how to improve our control over them. Exciting comparisons between theory, numerical simulations and experiments open new paths to explore these intricate objects.
Project
The prospective development of new technologies based on domain walls motion prompts the search to deepen the understanding of domain walls dynamics. From the growing of ferromagnetic thin-films, up to the observation of ferromagnetic domain walls statics and dynamics, by simulations that emulate experimental protocols, and new approaches to tackle this problem numerically and analytically, I collaborate with people around the world to better understand how to control ferromagnetic domain walls.
Project
Orientational glasses have translational order, but orientational disorder. In this sense, they represent a simplified framework to study the intriguing properties of glasses... and we exploit this, with a synergistic interaction between theoreticians, experimentalists and computational scientists :)