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Diaz-Mendez, Rogelio
Publications (4 of 4) Show all publications
Mendoza-Coto, A., Nicolao, L. & Diaz-Mendez, R. (2019). On the mechanism behind the inverse melting in systems with competing interactions. Scientific Reports, 9, Article ID 2020.
Open this publication in new window or tab >>On the mechanism behind the inverse melting in systems with competing interactions
2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 2020Article in journal (Refereed) Published
Abstract [en]

The competition between a short range attractive interaction and a nonlocal repulsive interaction promote the appearance of modulated phases. In this work we present the microscopic mechanisms leading to the emergence of inverse transitions in such systems by considering a thorough mean-field analysis of a variety of minimal models with different competing interactions. We identify the specific connections between the characteristic energy of the homogeneous and modulated phases and the observed reentrant behaviors in the phase diagram. In particular, we find that reentrance is appreciable when the characteristic energy cost of the homogeneous and modulated phases are comparable to each other, and for systems in which the local order parameter is limited. In the asymptotic limit of high energy cost of the homogeneous phase we observe that the degree of reentrance decreases exponentially with the ratio of the characteristic energy cost of homogeneous and modulated phases. These mean-field results are confronted with Langevin simulations of an effective coarse grained model, confirming the expected extension of the reentrance in the phase diagram. These results shed new light on many systems undergoing inverse melting transitions by qualitatively improving the understanding of the interplay of entropy and energy around the inverse melting points.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:kth:diva-245135 (URN)10.1038/s41598-018-38465-8 (DOI)000458619600020 ()30765837 (PubMedID)2-s2.0-85061574004 (Scopus ID)
Note

QC 20190313

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-03-13Bibliographically approved
Diaz-Mendez, R., Pupillo, G., Mezzacapo, F., Wallin, M., Lidmar, J. & Babaev, E. (2019). Phase-change switching in 2D via soft interactions. Soft Matter, 15(3), 355-358
Open this publication in new window or tab >>Phase-change switching in 2D via soft interactions
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2019 (English)In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 15, no 3, p. 355-358Article in journal (Refereed) Published
Abstract [en]

We present a new type of phase-change behavior relevant for information storage applications, that can be observed in 2D systems with cluster-forming ability. The temperature-based control of the ordering in 2D particle systems depends on the existence of a crystal-to-glass transition. We perform molecular dynamics simulations of models with soft interactions, demonstrating that the crystalline and amorphous structures can be easily tuned by heat pulses. The physical mechanism responsible for this behavior is a self-assembled polydispersity, that depends on the cluster-forming ability of the interactions. Therefore, the range of real materials that can perform such a transition is very wide in nature, ranging from colloidal suspensions to vortex matter. The state of the art in soft matter experimental setups, controlling interactions, polydispersity and dimensionality, makes it a very fertile ground for practical applications.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-244117 (URN)10.1039/c8sm01738g (DOI)000457278300001 ()30556570 (PubMedID)2-s2.0-85060062234 (Scopus ID)
Note

QC 20190219

Available from: 2019-02-19 Created: 2019-02-19 Last updated: 2019-05-10Bibliographically approved
Wang, W., Diaz-Mendez, R. & Capdevila, R. (2019). Solving the one-dimensional Ising chain via mathematical induction: an intuitive approach to the transfer matrix. European journal of physics, 40(6), Article ID 065102.
Open this publication in new window or tab >>Solving the one-dimensional Ising chain via mathematical induction: an intuitive approach to the transfer matrix
2019 (English)In: European journal of physics, ISSN 0143-0807, E-ISSN 1361-6404, Vol. 40, no 6, article id 065102Article in journal (Refereed) Published
Abstract [en]

The aim of this work is to present a formulation to solve the one-dimensional Ising model using the elementary technique of mathematical induction. This formulation is physically clear and leads to the same partition function form as the transfer matrix method, which is a common subject in the introductory courses of statistical mechanics. In this way our formulation is a useful tool to complement the traditional more abstract transfer matrix method. The method can be straightforwardly generalised to other short-range chains, coupled chains and is also computationally friendly. These two approaches provide a more complete understanding of the system, and therefore our work can be of broad interest for undergraduate teaching in statistical mechanics.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2019
Keywords
Ising model, transfer matrix, mathematical induction
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-261934 (URN)10.1088/1361-6404/ab330c (DOI)000487685400001 ()
Note

QC 20191015

Available from: 2019-10-15 Created: 2019-10-15 Last updated: 2019-10-15Bibliographically approved
Diaz-Mendez, R., Lidmar, J. & Wallin, M. (2018). Scaling of the magnetic permeability at the Berezinskii–Kosterlitz–Thouless transition from Coulomb gas simulations. Journal of Statistical Mechanics: Theory and Experiment, 2018(12), Article ID 123203.
Open this publication in new window or tab >>Scaling of the magnetic permeability at the Berezinskii–Kosterlitz–Thouless transition from Coulomb gas simulations
2018 (English)In: Journal of Statistical Mechanics: Theory and Experiment, ISSN 1742-5468, E-ISSN 1742-5468, Vol. 2018, no 12, article id 123203Article in journal (Refereed) Published
Abstract [en]

A new approach to the Berezinskii–Kosterlitz–Thouless transition in the two-dimensional Coulomb gas model is explored by Monte Carlo simulation and finite size scaling. The usual mapping of a neutral two-dimensional superconductor in zero magnetic field to a Coulomb gas leads to an unscreened logarithmic interaction between the vortices, and with periodic boundary conditions vortex configurations are always vorticity neutral with an equal number of plus and minus vortices. We demonstrate that relaxing the neutrality condition has certain advantages. It leads to non-neutral vortex configurations that can appear in real systems with open boundary conditions and permits calculation of the compressibility, which for thin film superconductors corresponds to the magnetic permeability. The vortex-number fluctuation has remarkable scaling properties at and below the Berezinskii–Kosterlitz–Thouless transition. The fugacity variable becomes dangerously irrelevant in the low-temperature phase and leads to a multiplicative scaling correction to the mean-square vortex-number fluctuation and to the magnetic permeability. This multiplicative correction strongly affects the scaling properties of the vorticity fluctuation at and below the transition. Consequences of these findings are demonstrated using Monte Carlo simulations. Inclusion of the next-higher order correction to scaling is found to play an important role in the analysis of numerical data for the vortex number fluctuation and permits accurate determination of the critical properties.

Place, publisher, year, edition, pages
IOP Publishing, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-248133 (URN)10.1088/1742-5468/aae855 (DOI)000452045600003 ()2-s2.0-85059878709 (Scopus ID)
Note

QC 20190513

Available from: 2019-04-04 Created: 2019-04-04 Last updated: 2019-05-13Bibliographically approved
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