A5076509516- Physics of Superconductivity and Magnetism
- Magnetic properties of thin films
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Theoretical and Computational Physics
- Seismic Waves and Analysis
- Mechanical and Optical Resonators
- Stochastic processes and statistical mechanics
- Material Dynamics and Properties
- Quantum and electron transport phenomena
- thermodynamics and calorimetric analyses
- Mechanics and Biomechanics Studies
- Magnetic Properties of Alloys
- Advanced MEMS and NEMS Technologies
- Magnetic Field Sensors Techniques
- Multiferroics and related materials
- Phase Equilibria and Thermodynamics
- Sensor Technology and Measurement Systems
- Acoustic Wave Resonator Technologies
- Magnetic and Electromagnetic Effects
- Geophysical and Geoelectrical Methods
- Quantum Electrodynamics and Casimir Effect
- Shape Memory Alloy Transformations
- nanoparticles nucleation surface interactions
- Elasticity and Wave Propagation
National University of San Luis
2005-2021
Consejo Nacional de Investigaciones Científicas y Técnicas
2006-2021
Laboratoire des Solides Irradiés
2014
Bariloche Atomic Centre
2005-2012
Comisión Nacional de Energía Atómica
2007-2010
Abstract Order-disorder transitions between glassy phases are common in nature and yet a comprehensive survey on the entailed structural changes is challenging since constituents micro-scale. Vortex matter type-II superconductors model system where some of these experimental challenges can be tackled. Samples with point disorder present transition increasing density vortices. A quasi-crystalline phase, Bragg glass, nucleates at low densities. The vortex glass stable high densities expected...
The persistence of the first-order transition line in phase diagram mesoscopic Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$ vortex matter is detected down to a system size less than hundred vortices. Precise and highly-sensitive bulk currents AC magnetization techniques proved be mandatory order obtain this information. location lines are not altered by decreasing sample 20 $\mu$m. Nevertheless, onset irreversible affected increasing surface-to-volume ratio producing noticeable enlargement region above...
A generalization of the classical monomer site-bond percolation problem is studied in which linear k-uples nearest neighbor sites (site k-mers) and bonds (bond are independently occupied at random on a square lattice. We called this model polyatomic species or k-mer percolation. Motivated by considerations cluster connectivity, we have used two distinct schemes (denoted as S intersection B union B) for In B(S B), points said to be connected if sequence (or) joins them. By using Monte Carlo...
We report magnetization experiments in two magnetically isolated ferromagnetic nanotubes of perovskite La0.67Ca0.33MnO3. The results show that the magnetic anisotropy is determined by sample shape, although coercive field reduced incoherent reversal modes. temperature dependence reveals behavior dominated grain surface properties. These measurements were acquired using a silicon micromechanical oscillator working its resonant mode. sensitivity was enough to measure properties these samples...
In this work we revisit the vortex matter phase diagram in layered superconductors solving still open questions by means of AC and DC local magnetic measurements paradigmatic Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$ compound. We show that measuring with techniques is mandatory order to probe bulk response matter, particularly at high-temperatures where surface barriers for entrance dominate. From $T_{\rm FOT}$-evolution enthalpy latent-heat transition find that, contrary previous reports, nature...
We study finite-size effects at the onset of irreversible magnetic behaviour micron-sized Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ single crystals by using silicon micro-oscillators. find an irreversibility line appearing well below thermodynamic Bragg-glass melting a field which increases both with increasing sample radius and decreasing temperature. show that this size-dependent can be identified crossover between Larkin random manifold regimes vortex lattice transverse roughness. Our method...
We directly image individual vortex positions in nanocrystals order to unveil the structural property that contributes depletion of entropy jump entailed at first-order transition. On reducing nanocrystal size, density topological defects increases near edges over a characteristic length. Within this ``healing-length'' distance from sample edge, rows tend bend, while towards center sample, positional structure is what expected for Bragg-glass phase. This suggests healing length may be key...
A silicon micromechanical torsional oscillator is used to measure the hysteresis loops of two manganite La_0.67Ca_0.33MnO_3 nanotubes at different temperatures, applying an external field along its main axes. These structures are composed nanograins with a ferromagnetic core surrounded by dead layer. Micromagnetic calculations based on stochastic Landau-Lifshitz-Gilbert equation, performed validate simple model that allows for quantitatively describing behavior system. Further simulations...
In this work, a micromagnetometer employing nonlinear torsional resonator with high quality factor Q is presented experimentally. Oscillatory rotation of conducting plate in the sensed magnetic field H induces eddy currents that dissipate energy. Due to response oscillator, resulting mechanical damping originates frequency shifts resonance curve depend on H. Nonlinearity results from electrostatic detection, which introduces order electrical spring constants. The device fabricated standard...
Inferring the nature of disorder in media where elastic objects are nucleated is crucial importance for many applications but remains a challenging basic-science problem. Here we propose method to discern whether weak-point or strong-correlated dominates based on characterizing distribution interaction forces between mapped large fields-of-view. We illustrate our proposal with case-study system vortex structures type-II superconductors different pinning landscapes. Interaction force...
We investigated configurational changes in mesoscopic vortex matter with less than thousand vortices during flux penetration freestanding 50 μm diameter disks of Bi2Sr2CaCu2O8+δ. High-resolution AC and DC local magnetometry data reveal oscillations the transmittivity echoed peaks third-harmonics magnetic signal fainting on increasing density. By means extra experimental evidence a simple geometrical analysis we show that these features fingerprint discretized entrance single-shells having...
The physical pre-treatment of seeds is a growing field research in agricultural biotechnology. Among its possibilities, magnetopriming has received increasing attention the last two decades. Inspired by remarkable reports literature on effects static magnetic fields (SMF) maize seeds, we performed similar experiments, though expanding range SMF up to 350 mT, higher than most reported studies. With exposure durations 1 h, tested 7 different intensities, from 50 mT at increments mT. We...
We study the penetration field $H_{\rm P}$ for vortex nanocrystals nucleated in micron-sized samples with edges aligned along nodal and anti-nodal directions of d-wave superconducting parameter Bi$_2$Sr$_2$CaCu$_2$O$_{8 - \delta}$. Here we present evidence that parallel to direction is larger than antinodal case, $\sim 72$\,\% at low temperatures. This finding supports theoretical proposal surface Andreev bound states appearing a sample would produce an anomalous Meissner current increases...
We investigated configurational changes in mesoscopic vortex matter with less than thousand vortices during flux penetration freestanding 50 $\mu$m diameter disks of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8 +\delta}$. High-resolution AC and DC local magnetometry data reveal oscillations the transmittivity echoed peaks third-harmonics magnetic signal fainting on increasing density. By means extra experimental evidence a simple geometrical analysis we show that these features fingerprint discretized...