Publications by authors named "F Pignatelli Albarracin"
Exotic phases induced by RKKY interaction in the square lattice.
J Phys Condens Matter
September 2024
We study a model of Ising spins in which direct exchange interactions compete with the Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling, which may arise effectively from itinerant electrons. We consider the model in the two-dimensional square lattice and focus on values of the RKKY coupling constant (JRKKY) and the Fermi momentum (kF) that induce strong frustration. We study the low-temperature magnetic field phase diagram using Monte Carlo simulations, considering several nearest neighbors in the RKKY interaction.
View Article and Find Full Text PDFSkyrmions are of interest both from a fundamental and technological point of view, due to their potential to act as information carriers. But one challenge concerns their manipulation, especially at high temperature where thermal fluctuations eventually disintegrate them. Here we study the competition between skyrmions and a chiral spin liquid, using the latter as an entropic buffer to impose a quasivacuum of skyrmions.
View Article and Find Full Text PDFArticle Synopsis
- The study explores the dynamics of one-dimensional processes involving the adsorption and desorption of particles (like dimers and trimers), focusing on how these processes interact through their smaller parts (monomers).
- It highlights the emergence of nonlocal conservation laws and different motion sectors when particles can form or break apart under desorption, particularly noting effects for larger particle groups (k ≥ 3).
- The research finds that under attractive interactions at low temperatures, the time scales align with established models (Glauber dynamics), indicating a diffusive behavior, while repulsive interactions lead to metastable states that decay more slowly toward a crowded, partially jammed phase.
Article Synopsis
- The study examines how various metastable configurations in a chain of Ising spins, influenced by both first- and second-neighbor interactions, behave over time under Kawasaki dynamics.
- Different dynamic exponents are identified based on the coupling ratios and signs, with these metrics derived from finite-size scaling analyses of the relaxation times.
- At low temperatures, the researchers use exact diagonalizations of the evolution operator to calculate relaxation times, concluding that without metastability, the dynamics remain consistently diffusive.
A series of (N, O)-co-doped graphenes with different N and O loadings are prepared by the pyrolysis of natural chitosan. When the percentage of dopant increases, the conduction-band potential and charge-separation quantum yield increase, whereas the charge-separation lifetime decreases.
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