2016 Impact factor 1.461
Condensed Matter and Complex Systems

News / Highlights / Colloquia

EPJ B Video - EPJ B Colloquia, introductions to new research directions

Luciano Colombo explains the benefits of colloquia papers in EPJ B.

EPJB Colloquium - Embedded nanocrystals get reshaped by ion beams

A new Colloquium paper published in EPJ B looks at ion irradiation techniques as a means to control the structure of nanoclusters and nanocrystals embedded in solid materials, such as silica or silicon.

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EPJ B Highlight - Taking advantage of graphene defects

The scattering potential in real space calculated based on the Fourier image. © S. Koniakhin

New theoretical model of the effect of triangular defects in graphene provides numerical estimates of the resulting current rectification with potential applications in security screening.

Electronic transport in graphene contributes to its characteristics. Now, a Russian scientist is proposing a new theoretical approach to describe graphene with defects—in the form of artificial triangular holes—resulting in the rectification of the electric current within the material. Specifically, the study provides an analytical and numerical theory of the so-called ratchet effect —which results in a direct current under the action of an oscillating electric field, due to the skew scattering of electronic carriers by coherently oriented defects in the material. These findings are published in EPJ B by Sergei Koniakhin from the Ioffe Physical-Technical Institute and the Academic University - Nanotechnology Research and Education Centre, both affiliated with the Russian Academy of Sciences in St. Petersburg.

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EPJ B Highlight - Nano-pea pod model widens applications

The dependence of the continuous spectrum on the connecting wires’ length. © Eremin et al.

A new theoretical model outlines the conditions under which a novel nanostructure, such as the nano-pea pod, can exhibit localised electrons for electronics applications

Periodic chain-like nanostructures are widely used in nanoelectronics. Typically, chain elements include the likes of quantum rings, quantum dots, or quantum graphs. Such a structure enables electrons to move along the chain, in theory, indefinitely. The trouble is that some applications require localised electrons - these are no longer in a continuous energy spectrum but in a discrete energy spectrum, instead. Now, a new study by Russian scientists identifies ways of disturbing the periodicity of a model nanostructure to obtain the desired discrete spectrum with localised electrons. These findings have been published in EPJ B by Dr. Eremin from the Mordovian State University, in Saransk, Russia and colleagues.

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EPJ B Highlight - Inter-dependent networks stress test

Impact of network topologies. © Fu et al.

A new study relies on a complex systems modelling approach, known as graph theory, to analyze inter-dependent physical or social networks and improve their reliability in the event of failure

Energy production systems are good examples of complex systems. Their infrastructure equipment requires ancillary sub-systems structured like a network - including water for cooling, transport to supply fuel, and ICT systems for control and management. Every step in the network chain is interconnected with a wider network and they are all mutually dependent. A team of UK-based scientists has studied various aspects of inter-network dependencies, not previously explored. The findings have been published in EPJ B by Gaihua Fu from Newcastle University, UK, and colleagues. These findings could have implications for maximising the reliability of such networks when facing natural and man-made hazards.

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EPJ B Highlight - Unleashing the power of quantum dot triplets

Triple quantum dot system. © S. B. Tooski et al.

Another step towards faster computers relies on three coherently coupled quantum dots used as quantum information units, which could ultimately enhance quantum computers’ speed

Quantum computers have yet to materialise. Yet, scientists are making progress in devising suitable means of making such computers faster. One such approach relies on quantum dots—a kind of artificial atom, easily controlled by applying an electric field. A new study demonstrates that changing the coupling of three coherently coupled quantum dots (TQDs) with electrical impulses can help better control them. This has implications, for example, should TQDs be used as quantum information units, which would produce faster quantum computers due to the fact that they would be operated through electrical impulses. These findings have been published in EPJ B by Sahib Babaee Tooski and colleagues affiliated with both the Institute of Molecular Physics at the Polish Academy of Sciences, in Poznan, Poland, the University of Ljubljana and the Jožef Stefan Institute in Slovenia.

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EPJ B Colloquium - Next generation interatomic potentials for condensed matter systems

A small two-dimensional feed-forward Neural Network containing a single hidden layer.

More efficient computational methods are urgently needed to capture condensed matter systems in simulations. Electronic structure methods, such as density-functional theory (DFT), usually provide a good compromise between accuracy and efficiency, but they demand much computational power. For this reason, they are only applicable to small systems containing a few hundred atoms at most. Conversely, many interesting phenomena involve much larger systems comprising thousands of atoms or more. Considerable effort has been invested in the development of potentials that enable simulations to run on larger system and for longer times. Typically these potentials are based on physically-motivated functional forms. Therefore, while they perform very well for the specific applications for which they have been designed, they cannot easily be transferred from one system to another. Moreover, their numerical accuracy is restricted by the intrinsic limitations of the imposed functional forms. In this EPJ B Colloquium, Handley and Behler survey several novel types of potentials emerged in recent years, which are not based on physical considerations.

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EPJ B Highlight - Ti-V alloys’ superconductivity: inherent, not accidental

The variation of the superconducting transition temperature (Tc) as a function of vanadium concentration along with the binary phase information for the quenched Ti-V alloys. © Matin et al.

All of the Ti-V alloys could display a relatively high superconducting transition temperature, as it is their unusual physical properties that influence this property, unlike previously thought

Physicists from India have shed new light on a long-unanswered question related to superconductivity in so-called transition metal binary alloys. The team revealed that the local magnetic fluctuations, or spin fluctuations, an intrinsic property of Titanium-Vanadium (Ti-V) alloys, influences superconductivity in a way that is more widespread than previously thought. They found that it is the competition between these local magnetic fluctuations and the interaction between electrons and collective excitations, referred to as phonons, which determine the superconductivity. Dr. Matin, from the Raja Ramanna Center for Advanced Technology, Indore, India, and colleagues published their findings in a study in EPJ B

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EPJ B Highlight - Market crashes are anomalous features in the financial data fractal landscape

Graph of the normalised empirically found distribution of the American Dow Jones Industrial Average index, DJIA (red squares), and European Euro Stoxx 50 (blue circles) index data with prices recorded every minute data along with the Standard Normal curve for comparison. © Green et al.

Analysing the adequation of financial data structure with its expected fractal scaling could help early detection of extreme financial events because these represent a scaling irregularity

Due to their previously discovered fractal nature, financial data patterns are self-similar when scaling up. New research shows that the most extreme events in financial data dynamics—reflected in very large price moves—are incompatible with multi-fractal scaling. These findings have been published in EPJ B by physicist Elena Green from the National University of Ireland, Maynooth, Ireland and colleagues. Understanding the multi-fractal structure of financially sound markets could, ultimately, help in identifying structural signs of impending extreme events.

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EPJ B Highlight - Particles near absolute zero do not break the laws of physics after all

A free particle strongly coupled to a heat bath. © Adamietz et al.

A change of models demystifies anomalous particle behaviour at very low temperatures, confirming that the third law of thermodynamics cannot be violated

In theory, the laws of physics are absolute. However, when it comes to the laws of thermodynamics—the science that studies how heat and temperature relate to energy—there are times where they no longer seem to apply. In a paper recently published in EPJ B, Robert Adamietz from the University of Augsburg, Germany, and colleagues have demonstrated that a theoretical model of the environment’s influence on a particle does not violate the third law of thermodynamics, despite appearances to the contrary. These findings are relevant for systems at the micro or nanometer scale that are difficult to decouple from the heat or the quantum effects exerted by their environment.

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Acting EiC: Heiko Rieger

Executive Editors:
Eduardo Hernandez, Heiko Rieger, Bikas K. Chakrabarti, Wenhui Duan
I am naturally indebted to you and the referees who contributed to this success with your time and constructive advice.

Hamid Assadi

ISSN (Print Edition): 1434-6028
ISSN (Electronic Edition): 1434-6036

© EDP Sciences, Società Italiana di Fisica and Springer-Verlag

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