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EPJPV Highlight - How cool is floating PV

Example of effect of wind on two panels

The Editors-in-Chief of EPJ Photovoltaics, Pere Roca i Cabarrocas and Jean-Louis Lazzari, are pleased to highlight an important paper published recently in the Special Issue on ‘WCPEC-8: State of the Art and Developments in Photovoltaics’.

The article “How cool is floating PV? A state-of-the-art review of floating PV's potential gain and computational fluid dynamics modeling to find its root cause” is the result of the joint efforts of Gofran Chowdhury (imec, EnergyVille and University of Leuven), Mohamed Haggag (imec and University of Leuven), and Jef Poortmans (imec, EnergyVille, University of Hasselt and University of Leuven).

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EPJ B Highlight - How a transparent conductor responds to strain

A single crystal unit of SrVO3

First-principles calculations show how to manipulate some transition metal oxides’ optical and electronic properties for use in thin-film devices.

Liquid crystal displays, touchscreens, and many solar cells rely on thin-film crystalline materials that are both electrically conductive and optically transparent. But the material most widely used in these applications, indium tin oxide (ITO), is brittle and susceptible to cracking. Researchers seeking alternatives have set their sights on strontium vanadate (SrVO3), a material that ticks all the boxes for a transparent conductor. In a study published in EPJ B, Debolina Misra, of the Indian Institute of Information Technology, Design and Manufacturing, Kancheepuram, India, and her colleagues now calculate how SrVO3‘s optical and electron transport properties vary in response to strain. Their simulations provide a detailed mechanism for tuning these properties to optimize the material’s utility in different devices and applications.

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EPJ ST Highlight - Many-body interactions feel the heat: Introducing thermal field theory

A many-body process at zero temperature which becomes much more complicated when temperature is a factor. Credit: Robert Lea

Thermal field theory seeks to explain many-body dynamics at non-zero temperatures not considered in conventional quantum field theory.

Quantum field theory is a framework used by physicists to describe a wide range of phenomena in particle physics and is an effective tool to deal with complicated many-body problems or interacting systems.

Conventional quantum field theory describes systems and interactions at zero temperature and zero chemical potential, and interactions in the real world certainly do occur at non-zero temperatures. That means scientists are keen to discover what effects may arise as a result of non-zero temperature and what new phenomena could arise due to a thermal background. In order to understand this, physicists turn to a recipe for quantum field theory in a thermal background — thermal field theory.

In a new paper in EPJ ST, Munshi G. Mustafa, Senior Professor at the Saha Institute of Nuclear Physics, Kolkata, India, introduces a thermal field theory in a simple way weaving together the details of its mathematical framework and its application.

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EPJ Plus Focus Point Issue: Advances in Cryogenic Detectors for Dark Matter, Neutrino Physics, and Astrophysics

Guest Editor: Luca Pattavina

The papers included in this Focus Point collection offer a glimpse of the very broad range of applications of low-temperature detectors. This class of detectors has seen in recent years a boost in its performance and in the achieved background levels. Nowadays, cryogenic detectors are considered a leading technology in the investigation of the fundamental properties of the most abundant particles in the Universe: neutrinos and Dark Matter, and their applications reach out to nuclear, particle, and astroparticle physics. The papers included in the collection cover the most recent technological progress of low-temperature detectors, from different perspectives (e.g. computational approach, material development). The research groups that contributed to this collection show the range of methods available to tackle the latest experimental challenges of the community.

All articles are available here and are freely accessible until 27 September 2023. For further information, read the Editorial.

EPJ ST Highlight - Investigating the Ising model with magnetisation

Evolution from paramagnetism to ferromagnetism.

Researchers have explored the evolution of systems of interacting spins, as they transition from random to orderly alignments. Through new simulations, they show that this evolution can be investigated by measuring the changing strength of the system’s magnetism.

The Ising model describes systems of interacting atomic spins relaxing from a ‘paramagnetic’ state – whose spins point in random directions, to a ‘ferromagnetic’ state – whose spins spontaneously align with each other. So far, the nonequilibrium dynamics of this transition has been studied by measuring the growth of regions, or ‘domains’ of aligned spins. In new research published in EPJ ST, researchers led by Wolfhard Janke at the University of Leipzig, Germany, show how this can be done far more easily by measuring the strength of the system’s magnetisation. The team’s discovery could help researchers to better understand the atomic-scale interactions underlying many different phenomena in nature: from electrostatic forces, to neuroscience and economics.

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EPJ D Highlight - Looking deeper into graphene using rainbow scattering

An illustration of a kilonova the collision of neutron stars generating conditions extreme enough to forge the Universe’s heavy elements. Credit: Robin Dienel/The Carnegie Institution for ScienceContact

New research uses protons to shine a light on the structure and imperfections of this two-dimensional wonder material

Graphene is a two-dimensional wonder material that has been suggested for a wide range of applications in energy, technology, construction, and more since it was first isolated from graphite in 2004.

This single layer of carbon atoms is tough yet flexible, light but with high resistance, with graphene calculated to be 200 times more resistant than steel and five times lighter than aluminium.

Graphene may sound perfect, but it very literally is not. Isolated samples of this 2D allotrope aren’t perfectly flat, with its surface rippled. Graphene can also feature structural defects that can, in some cases, be deleterious to its function and, in other instances, can be essential to its chosen application. That means that the controlled implementation of defects could enable fine-tuning of the desired properties of two-dimensional crystals of graphene.

In a new paper in EPJ D, Milivoje Hadžijojić and Marko Ćosić, both of the Vinča Institute of Nuclear Sciences, University of Belgrade, Serbia, examine the rainbow scattering of photons passing through graphene and how it reveals the structure and imperfections of this wonder material.

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EPJ B Highlight - How a molecular motor moves in a network

Ratchets transfer energy in a lattice arrangement. Credit: M. A. Taye

A new study determines the efficiency of a single-molecule heat engine by considering a series of ratchets that transfer energy along a network.

From internal combustion engines to household refrigerators, heat engines are a ubiquitous component of daily life. These machines convert heat into usable energy which can then be used to do work. Heat engines can be as small as a single molecule whose random movements exchange energy with the environment. But determining the efficiency of a molecular heat engine is no simple task. In a study published in EPJ B, Mesfin Asfaw Taye, of West Los Angeles College, California, USA now calculates the performance of a molecular heat engine in terms of a series of molecular ratchets that transfer energy, step-wise, in one direction. He shows and discusses how to manipulate such a system for transporting a particle along a complex path.

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EPJ E Highlight - Exploring the elasticity of colloidal suspensions

Particles in a colloidal suspension.
Author: Zephyris, CC BY-SA 3.0 https://creativecommons.org/ licenses/by-sa/3.0, via Wikimedia Commons

Experiments reveal that under the right conditions, the elasticity of colloidal suspensions will peak at a certain value, which depends both on the deformation applied to the material and the strength of attraction between its solid particles.

The behaviours of colloidal materials – where tiny solid particles are suspended in fluid – depend strongly on how the particles interact with each other. Through new research published in EPJ E, a team led by Pascal Hébraud at the University of Strasbourg, France, show how under certain conditions, the elasticity of silica-based colloids subjected to oscillating flows will peak at a certain value. Their discovery could lead to improved techniques for manipulating the behaviour of colloidal materials, used in fields as wide-ranging as materials science, food technology, construction, and nanotechnology.

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EPJ B Highlight - Calculating thermal properties from phonon behaviours

Calculating phonon dispersions in ScAgC

A new study determines the thermal properties of advanced solid materials, based on first-principles calculations of quantum vibrations.

As the energy demands of our modern world continue to grow, there is a crucial need to understand how heat flows through the materials we use to build our technology. Through new research published in EPJ B, Vinod Solet and Sudhir Pandey at the Indian Institute of Technology Mandi have accurately estimated the thermal properties of a particularly promising alloy, based on first-principles calculations of phonons. Composed of scandium (Sc), silver (Ag), and carbon (C), this alloy could soon become a key component of devices which convert heat into electricity, while its low reflectivity and strong photon absorption would make it especially well-suited for highly efficient solar cells.

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EPJ D Highlight - Looking deeper into violent neutron star collisions to find the origins of heavy elements

An illustration of a kilonova the collision of neutron stars generating conditions extreme enough to forge the Universe’s heavy elements. Credit: Robin Dienel/The Carnegie Institution for ScienceContact

The gold that makes up your most precious jewellery may have been forged in a violent cosmic collision millions or billions of light years away between two neutron stars. New research seeks to better understand this process.

There is only a single confirmed site in the Universe capable of generating conditions extreme enough to initiate the production process for many of the heaviest elements in the Universe, including gold, platinum, uranium – neutron star mergers. These mergers are the only event observed to-date that can produce the incredible densities and temperatures needed to power the rapid neutron capture process.

In a new paper in EPJ D, Andrey Bondarev, a postdoc researcher at Helmholtz Institute Jena, James Gillanders a postdoc researcher in Rome, and their colleagues examine the spectra from the kilonova AT2017gfo to investigate the presence of forged tin, by looking for spectral features caused by its forbidden transitions.

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Managing Editors
Sandrine Karpe and Vijala Kiruvanayagam (EDP Sciences) and Sabine Lehr (Springer-Verlag)
Thank you very much, Isabelle! Very timely. And the cover looks fantastic! We are grateful for the great collaboration! Best wishes.

Dirk Helbing, ETH Zurich, Switzerland
Editor EPJ Special Topics 214, 2012

ISSN: 1951-6355 (Print Edition)
ISSN: 1951-6401 (Electronic Edition)

© EDP Sciences and Springer-Verlag