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Statistical Physics in Extremadura This is the FB webpage of the group of Statistical Physics in the Faculty of Physics of the University of Extremadura.

Here, we will release news, events and info of our daily work.

25/05/2026

🌟𝐍𝐞𝐰 𝐫𝐞𝐯𝐢𝐞𝐰: 𝗘𝘅𝗽𝗹𝗼𝗿𝗶𝗻𝗴 𝘁𝗵𝗲 𝗗𝘆𝗻𝗮𝗺𝗶𝗰𝘀 𝗼𝗳 𝗖𝗼𝗻𝗳𝗶𝗻𝗲𝗱 𝗚𝗿𝗮𝗻𝘂𝗹𝗮𝗿 𝗙𝗹𝘂𝗶𝗱𝘀🌟

This review explains how a simple theoretical model can describe the surprising behavior of granular materials - collections of macroscopic particles such as sand, grains, or powders - when they are confined in a shallow vibrating box. Unlike ordinary fluids, these systems constantly lose energy during collisions, so they must be continuously driven to keep moving. The work reviewed here focuses on a model that captures how vertical vibrations inject energy into the particles and redistribute it through collisions, allowing the system to remain active and fluid-like. The importance of this model is that it turns a very complicated experimental setup into a mathematically tractable problem while still reproducing many observed behaviors.

The review summarizes how kinetic theory can predict key properties of these driven granular systems, including their steady states, transport properties, and stability. It also shows how the model successfully describes mixtures of different particles, where unusual nonequilibrium effects appear, such as unequal sharing of energy between species and spontaneous segregation. More recent studies discussed in the review reveal that the same framework can also explain exotic phenomena including quasicrystal formation, long-range order, and unusual collective phases in driven matter.

📘📘
𝑫𝒚𝒏𝒂𝒎𝒊𝒄 𝑷𝒓𝒐𝒑𝒆𝒓𝒕𝒊𝒆𝒔 𝒊𝒏 𝒂 𝑪𝒐𝒍𝒍𝒊𝒔𝒊𝒐𝒏𝒂𝒍 𝑴𝒐𝒅𝒆𝒍 𝒇𝒐𝒓 𝑪𝒐𝒏𝒇𝒊𝒏𝒆𝒅 𝑮𝒓𝒂𝒏𝒖𝒍𝒂𝒓 𝑭𝒍𝒖𝒊𝒅𝒔: 𝑨 𝑹𝒆𝒗𝒊𝒆𝒘
Link to the review in 𝙀𝙣𝙩𝙧𝙤𝙥𝙮.
https://www.mdpi.com/1099-4300/28/4/454
📘📘

13/05/2026

🔬𝐖𝐡𝐞𝐧 𝐝𝐮𝐦𝐛𝐛𝐞𝐥𝐥𝐬 𝐭𝐞𝐚𝐜𝐡 𝐮𝐬 𝐛𝐢𝐠 𝐥𝐞𝐬𝐬𝐨𝐧𝐬 𝐚𝐛𝐨𝐮𝐭 𝐨𝐫𝐝𝐞𝐫 🔵🟠🟣

❓ What happens when microscopic “dumbbell-shaped” particles are squeezed into an ultra-narrow line where they can barely move but can still rotate?

Our work reveals something fascinating: these particles spontaneously organize themselves into surprisingly complex patterns, purely because of geometry and entropy. At low density, the particles point in many directions almost randomly. But as the system becomes crowded, they begin to “choose” preferred orientations, forming two dominant alignment directions — a kind of collective behavior emerging between particles.

We also uncovered long-range correlations and hidden ordering effects due to the interplay between positional and orientational correlations that resemble behaviors seen in liquid crystals, biological systems, and confined materials.

𝙒𝙝𝙮 𝙙𝙤𝙚𝙨 𝙞𝙩 𝙢𝙖𝙩𝙩𝙚𝙧❓
Because understanding how simple shapes self-organize under confinement can help scientists design:
🧪 smarter soft materials
📦 better nanoparticle packing systems
🧬 improved models for biological transport in narrow channels
⚙️ future nanotechnology and microfluidic devices

This work shows how complexity can emerge from incredibly simple rules — one of the most beautiful ideas in physics.

📄 Link to the article in 𝑷𝒉𝒚𝒔𝒊𝒄𝒂𝒍 𝑹𝒆𝒗𝒊𝒆𝒘 𝑬: https://journals.aps.org/pre/abstract/10.1103/sdt7-t224

27/04/2026

El pasado 22 de abril celebramos el acto de 𝑺𝒂𝒏𝒕𝒐 𝑻𝒐𝒎𝒂́𝒔 𝒅𝒆 𝑨𝒒𝒖𝒊𝒏𝒐 en la Universidad de Extremadura, un evento muy especial para nuestra comunidad académica.

En él, nuestros antiguos doctorandos y actuales investigadores postdoctorales del grupo, 𝗝𝗲𝘀𝘂́𝘀 𝗠𝗮𝗿𝗶́𝗮 𝗠𝗮𝗿𝗰𝗼𝘀 𝗠𝗲𝗿𝗶𝗻𝗼 𝘆 𝗔𝗻𝗮 𝗠𝗮𝗿𝗶́𝗮 𝗠𝗼𝗻𝘁𝗲𝗿𝗼 𝗠𝗮𝗿𝘁𝗶́𝗻𝗲𝘇, recibieron oficialmente el Premio Extraordinario de Doctorado.

Un reconocimiento más que merecido a su esfuerzo, dedicación y excelencia investigadora 👏

¡Enhorabuena a ambos!

21/04/2026

𝐃𝐞𝐬𝐜𝐚𝐫𝐭𝐞𝐬’ 𝐂𝐞𝐧𝐭𝐮𝐫𝐢𝐞𝐬-𝐎𝐥𝐝 𝐈𝐝𝐞𝐚 𝐇𝐞𝐥𝐩𝐬 𝐄𝐱𝐩𝐥𝐚𝐢𝐧 𝐖𝐡𝐲 𝐇𝐨𝐭 𝐂𝐚𝐧 𝐂𝐨𝐨𝐥 𝐅𝐚𝐬𝐭𝐞𝐫 🔥🌡️❄️

Hot water can sometimes cool faster than cold—a surprising effect that has puzzled scientists for decades. In this work, we show that this phenomenon can be understood and precisely controlled by combining a modern “memory-based” model of cooling with a little-known idea that dates back to René Descartes. His proposed thermal setup, involving three different temperature reservoirs, turns out to provide a powerful way to uncover when and how this effect occurs.

In standard explanations, the Mpemba effect is often linked to complex physical mechanisms. Here, we show instead that it can arise even in a simple model of cooling, as long as the system retains a short memory of its past. Building on this, we analyze a protocol inspired by Descartes in which two samples, initially at different temperatures (hot and warm), are quenched to a common cold reservoir at different times. This three-reservoir arrangement allows us to clearly separate the roles of timing and temperature in the cooling process.

What is new in our work is a complete analytical description of the conditions under which the effect appears, how strong it can be, and how to optimize it. We also find that adding this extra reservoir does not necessarily make the effect stronger than in simpler setups.

By linking a historical idea with modern theory, our results highlight how the path taken—not just the starting point—governs how systems cool.

Link to the article in 𝑱𝒐𝒖𝒓𝒏𝒂𝒍 𝒐𝒇 𝑷𝒉𝒚𝒔𝒊𝒄𝒔 𝑨: https://iopscience.iop.org/article/10.1088/1751-8121/ae57ed

10/04/2026

𝐍𝐞𝐰 𝐭𝐡𝐞𝐨𝐫𝐲 𝐩𝐫𝐞𝐝𝐢𝐜𝐭𝐬 𝐡𝐨𝐰 𝐬𝐡𝐚𝐤𝐞𝐧 𝐠𝐫𝐚𝐢𝐧 𝐦𝐢𝐱𝐭𝐮𝐫𝐞𝐬 𝐟𝐥𝐨𝐰 𝐚𝐧𝐝 𝐬𝐞𝐩𝐚𝐫𝐚𝐭𝐞 𝐢𝐧 𝐭𝐢𝐠𝐡𝐭 𝐬𝐩𝐚𝐜𝐞𝐬 🔵🔴🟢

Granular materials can behave in surprising ways when particles of different sizes are confined between two close plates and continuously shaken. In this paper, we developed a general theory that predicts how such mixtures move, resist deformation, and separate under those conditions, even when the particles are already fairly crowded. Earlier studies could usually treat only very dilute mixtures or special cases, such as when one component was present in tiny amounts. The new result here is a broader description for mixtures with arbitrary composition at moderate density, together with explicit formulas for key transport properties and a criterion that tells us when larger grains tend to accumulate near the colder side and when they instead migrate toward the hotter side. This is important because the tendency of granular mixtures to mix or segregate affects many natural and industrial systems, from powders and grains to processing technologies that rely on particulate materials. By turning a complicated many-particle problem into a practical predictive framework, our work helps clarify how confinement, dissipation, density, and particle differences combine to control the behavior of vibrated granular mixtures.

Link to the article in 𝘗𝘩𝘺𝘴𝘪𝘤𝘴 𝘰𝘧 𝘍𝘭𝘶𝘪𝘥𝘴: https://doi.org/10.1063/5.0321569

27/03/2026

𝐇𝐨𝐰 𝐭𝐢𝐠𝐡𝐭𝐥𝐲 𝐜𝐚𝐧 𝐝𝐢𝐟𝐟𝐞𝐫𝐞𝐧𝐭-𝐬𝐢𝐳𝐞𝐝 𝐜𝐨𝐢𝐧𝐬 𝐩𝐚𝐜𝐤 𝐭𝐨𝐠𝐞𝐭𝐡𝐞𝐫? 𝐀 𝐧𝐞𝐰 𝐫𝐮𝐥𝐞 𝐛𝐫𝐢𝐧𝐠𝐬 𝐬𝐮𝐫𝐩𝐫𝐢𝐬𝐢𝐧𝐠 𝐬𝐢𝐦𝐩𝐥𝐢𝐜𝐢𝐭𝐲

We found a simple rule that predicts how tightly a mixture of different-sized disks (think coins on a table) can be packed without forming an ordered pattern. This matters because such “random close packing” underlies materials ranging from powders and grains to emulsions and even biological tissues.

Until now, estimating this packing limit for mixtures required complicated models or case-by-case simulations. Our work shows that, for disks of different sizes, the answer can be captured by a single quantity that measures how triplets of particles crowd each other locally. Once this quantity is known, the maximum packing fraction follows almost as a straight line.

We tested this idea against computer simulations for many mixtures and found that the data collapse onto a simple universal trend. This means that very different mixtures behave in a surprisingly similar way when viewed through the right lens.

The result provides an easy-to-use tool to estimate packing limits and suggests that local three-particle constraints play a key role in how disordered materials organize at high density.

Link to the article in 𝑇ℎ𝑒 𝐽𝑜𝑢𝑟𝑛𝑎𝑙 𝑜𝑓 𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑃ℎ𝑦𝑠𝑖𝑐𝑠: https://doi.org/10.1063/5.0328013

04/02/2026

¡TENEMOS NUEVO DOCTOR!🎓📜

Nuestro doctorando Miguel Aguilar Janita defendió su tesis doctoral titulada “Física de sistemas complejos: de los vidrios de espín a los sistemas ecológicos y sociales”, dirigida por Nagi Khalil Rodríguez y Juan Jesús Ruiz Lorenzo.
La tesis ha obtenido la máxima calificación académica, culminando así varios años de trabajo y dedicación.
Con la defensa, Miguel alcanza el máximo grado académico y comienza, en nuestro grupo, una nueva etapa en su trayectoria investigadora

¡Enhorabuena, Miguel!🎉🎓

22/12/2025

Desde nuestro grupo de investigación queremos dar la enhorabuena a nuestros compañeros Javier Moreno y Juan Jesús Ruiz Lorenzo por la publicación de un artículo de revisión en Reviews of Modern Physics (https://journals.aps.org/rmp/abstract/10.1103/ctp2-zwyr), una de las revistas de mayor impacto en física, que recoge y sintetiza los avances más importantes de las últimas décadas en el estudio de los spin glasses.

📈📚
El trabajo ofrece una visión completa y accesible de cómo estos materiales magnéticos desordenados, considerados un paradigma de los sistemas complejos, presentan comportamientos tan singulares como el envejecimiento, la memoria y el rejuvenecimiento. Gracias a la combinación de experimentos de alta precisión en cristales de gran calidad, desarrollos teóricos y simulaciones numéricas a gran escala, el artículo muestra por primera vez una convergencia cuantitativa entre teoría, simulación y experimento, permitiendo entender mejor la dinámica fuera del equilibrio de estos sistemas y su rica estructura interna.
📈📚

Enhorabuena de nuevo a Javier Moreno y Juan Jesús Ruiz Lorenzo por esta magnífica contribución, fruto de una colaboración internacional de primer nivel y de gran relevancia para la física de la materia condensada y el estudio de los sistemas complejos.

06/10/2025

¡ENHORABUENA, DOCTORA!🎓👨‍🎓

Nuestro doctoranda Ana María Montero Martínez alcanzó el día 12 de septiembre el máximo grado académico con la defensa de la tesis doctoral "Equilibrium properties of strongly confined fluids", dirigida por Andrés Santos.

Tras la defensa, Ana ya ha comenzado su etapa posdoctoral en nuestro grupo.

29/09/2025

El 11 de septiembre tuvimos el gusto de recibir en nuestro grupo a la doctora Sophie Hermann, de la Universidad de la Sorbona (París). Durante su visita, nos compartió un seminario muy interesante titulado “Noether's theorem and hyperforces in statistical mechanics”.

¡Gracias, Sophie, por la charla y por compartir tu trabajo con nosotros!

Dirección

Avenida Elvas S/n
Badajoz
06006

Página web

https://fisteor.cms.unex.es/

Notificaciones

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