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Hierarchical Interdiffusion Kinetics in Nanoscale Ni/Al Multilayers
Authors:
S. S. Riegler,
I. Gallino,
N. J. Peter,
A. Tarasov,
T. Meyer,
J. Schmauch,
C. Pauly,
M. Frey,
Y. H. Sauni Camposano,
H. Bartsch,
R. Schwaiger,
P. Schaaf,
R. Busch,
J. Arlt
Abstract:
Reactive metallic multilayers store chemical energy that can be released rapidly through interdiffusion and intermetallic formation. Predictive control of this heat release requires distinguishing transport and phase-formation processes that occur in rapid succession. Here we combine free-standing nanoscale Ni/Al multilayers with chip-based flash calorimetry and isoconversional kinetic analysis ov…
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Reactive metallic multilayers store chemical energy that can be released rapidly through interdiffusion and intermetallic formation. Predictive control of this heat release requires distinguishing transport and phase-formation processes that occur in rapid succession. Here we combine free-standing nanoscale Ni/Al multilayers with chip-based flash calorimetry and isoconversional kinetic analysis over five orders of magnitude in heating rate. Selected reaction states are quenched and examined by scanning transmission electron microscopy. This workflow separates pre-ignition interdiffusion into two regimes and quantifies activation energies of (81 $\pm$ 24) and (168 $\pm$ 17) kJ/mol, consistent with grain-boundary and lattice diffusion of Ni in Al, respectively. Microscopy supports this assignment: no significant compositional changes are observed after the first regime, whereas the second increases the Ni content of the Al layers and produces Ni-enriched features spaced by 5$-$10 nm, matching the Al grain size. These results identify the Al grain-boundary network as the dominant low-barrier pathway, providing rapid transport across the Al layers and priming lattice-mediated mixing and intermetallic phase formation. More broadly, the workflow links calorimetric signatures to pathway-specific kinetics and transient microstructures, enabling direct assessment of how microstructural design redirects coupled transport and reaction pathways in reactive multilayers and other materials driven far from equilibrium.
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Submitted 21 August, 2026; v1 submitted 10 June, 2026;
originally announced June 2026.
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Recent Advances in Metallic Glasses
Authors:
Silvia Bonfanti,
Ralf Busch,
Jesper Byggmästar,
Jeppe C. Dyre,
Jürgen Eckert,
Spencer Fajardo,
Michael L. Falk,
Isabella Gallino,
Jamie J. Kruzic,
Jiayin Lu,
Giulio Monaco,
Misaki Ozawa,
Anshul D. S. Parmar,
Chris H. Rycroft,
Srikanth Sastry
Abstract:
This paper reviews recent advances in the field of metallic glasses, focusing on the development of novel experimental techniques and in silico models. We discuss progress in experimental characterization, additive manufacturing, multiscale modeling approaches, and the growing role of machine learning in understanding and designing these complex materials. On the experimental side, we highlight me…
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This paper reviews recent advances in the field of metallic glasses, focusing on the development of novel experimental techniques and in silico models. We discuss progress in experimental characterization, additive manufacturing, multiscale modeling approaches, and the growing role of machine learning in understanding and designing these complex materials. On the experimental side, we highlight measurements of thermophysical properties of supercooled liquids via fast chip calorimetry and enhancements in mechanical properties through rejuvenation treatments. This work underscores the crucial role of short-range order and medium-range order in controlling metallic glass mechanical properties. Recent progress in structural probes allows in situ observations of deformation mechanisms, positioning the field well to further advance our understanding of mechanical properties. Additive manufacturing of metallic glasses is discussed as one encouraging new manufacturing route for metallic glasses. We examine laser powder-bed fusion process physics and the central trade-off between amorphicity and densification, including heat affected zone devitrification and defects formation, together with emerging mitigation strategies and applications. On the theoretical and simulation side, we review advances in nanoscale, mesoscale, and continuum modeling of metallic glasses that have led to promising approaches by which multiscale schemes can incorporate data sourced from atomic-scale simulations. These efforts have helped to elucidate the connection between the glass structure and mechanical and rheological responses. We also cover the development of machine learning interatomic potentials for metallic glasses, along with machine learning driven prediction of glass forming ability and inverse design methods. Finally, challenges and directions for future research are presented and discussed.
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Submitted 18 December, 2025;
originally announced December 2025.
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Break-down of the relationship between α-relaxation and equilibration in hydrostatically compressed metallic glasses
Authors:
Antoine Cornet,
Jie Shen,
Alberto Ronca,
Shubin Li,
Nico Neuber,
Maximilian Frey,
Eloi Pineda,
Thierry Deschamps,
Christine Martinet,
Sylvie Le Floch,
Daniele Cangialosi,
Yuriy Chushkin,
Federico Zontone,
Marco Cammarata,
Gavin B. M. Vaughan,
Marco di Michiel,
Gaston Garbarino,
Ralf Busch,
Isabella Gallino,
Celine Goujon,
Murielle Legendre,
Geeth Manthilake,
Beatrice Ruta
Abstract:
Glasses encode the memory of any thermo-mechanical treatment applied to them. This ability is associated to the existence of a myriad of metastable amorphous states which can be probed through different experimental pathways. It is usually assumed that this memory can be erased in the supercooled liquid, and that this process occurs on a time scale controlled by the α-relaxation. We find that this…
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Glasses encode the memory of any thermo-mechanical treatment applied to them. This ability is associated to the existence of a myriad of metastable amorphous states which can be probed through different experimental pathways. It is usually assumed that this memory can be erased in the supercooled liquid, and that this process occurs on a time scale controlled by the α-relaxation. We find that this assumption does not apply for hydrostatically compressed glasses. Annealing under pressure a prototypical metallic glass can irreversibly modify its dynamics, thermodynamics and structure, reduce the atomic mobility and lead to structural modifications of the first coordination shells which reduce the thermal stability with respect to a glass annealed in absence of pressure. When heated above their glass transition temperature, these compressed glasses do not convert into the pristine supercooled liquid, implying the existence of an additional process, beyond the α-relaxation, contributing to the equilibrium recovery of the material. These results establish pressure as a powerful tool for engineering non-equilibrium glassy materials with tailored properties, while deepening our understanding of relaxation dynamics in disordered systems under extreme conditions.
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Submitted 8 February, 2026; v1 submitted 20 September, 2024;
originally announced September 2024.
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Synthesis of layered gold tellurides AuSbTe and Au$_2$Te$_3$ and their semiconducting and metallic behavior
Authors:
Emma A. Pappas,
Rong Zhang,
Cheng Peng,
Robert T. Busch,
Jian-Min Zuo,
Thomas P. Devereaux,
Daniel P. Shoemaker
Abstract:
Previous studies on natural samples of pampaloite (AuSbTe) revealed the crystal structure of a potentially cleavable and/or exfoliable material, while studies on natural and synthetic montbrayite (Sb-containing Au$_2$Te$_3$) claimed various chemical compositions for this low symmetry compound. Few investigations of synthetic samples have been reported for both materials, leaving much of their chem…
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Previous studies on natural samples of pampaloite (AuSbTe) revealed the crystal structure of a potentially cleavable and/or exfoliable material, while studies on natural and synthetic montbrayite (Sb-containing Au$_2$Te$_3$) claimed various chemical compositions for this low symmetry compound. Few investigations of synthetic samples have been reported for both materials, leaving much of their chemical, thermal and electronic characteristics unknown. Here, we investigate the stability, electronic properties and synthesis of the gold antimony tellurides AuSbTe and Au$_{1.9}$Sb$_{0.46}$Te$_{2.64}$ (montbrayite). Differential thermal analysis and $\textit{in situ}$ powder x-ray diffraction revealed that AuSbTe is incongruently melting, while Au$_{1.9}$Sb$_{0.46}$Te$_{2.64}$ is congruently melting. Calculations of the band structures and four-point resistivity measurements showed that AuSbTe is a semiconductor and Au$_{1.9}$Sb$_{0.46}$Te$_{2.64}$ a metal. Various synthesis attempts confirmed the limited stable chemical composition of Au$_{1.9}$Sb$_{0.46}$Te$_{2.64}$, identified successful methods to synthesize both compounds, and highlighted the challenges associated with single crystal synthesis of AuSbTe.
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Submitted 3 February, 2025; v1 submitted 24 April, 2024;
originally announced April 2024.
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On the interplay of liquid-like and stress-driven dynamics in a metallic glass former observed by temperature scanning XPCS
Authors:
Maximilian Frey,
Nico Neuber,
Sascha Sebastian Riegler,
Antoine Cornet,
Yuriy Chushkin,
Federico Zontone,
Lucas Ruschel,
Bastian Adam,
Mehran Nabahat,
Fan Yang,
Jie Shen,
Fabian Westermeier,
Michael Sprung,
Daniele Cangialosi,
Valerio Di Lisio,
Isabella Gallino,
Ralf Busch,
Beatrice Ruta,
Eloi Pineda
Abstract:
Modern detector technology and highly brilliant fourth-generation synchrotrons allow to improve the temporal resolution in time-resolved diffraction studies. Profiting from this, we applied temperature scanning X-ray photon correlation spectroscopy (XPCS) to probe the dynamics of a Pt-based metallic glass former in the glass, glass transition region, and supercooled liquid, covering up to six orde…
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Modern detector technology and highly brilliant fourth-generation synchrotrons allow to improve the temporal resolution in time-resolved diffraction studies. Profiting from this, we applied temperature scanning X-ray photon correlation spectroscopy (XPCS) to probe the dynamics of a Pt-based metallic glass former in the glass, glass transition region, and supercooled liquid, covering up to six orders of magnitude in time scales. Our data demonstrates that the structural alpha-relaxation process is still observable in the glass, although it is partially masked by a faster source of decorrelation observed at atomic scale. We present an approach that interprets these findings as the superposition of heterogeneous liquid-like and stress-driven ballistic-like atomic motions. This work not only extends the dynamical range probed by standard isothermal XPCS, but also clarifies the fate of the alpha-relaxation across the glass transition and provides a new perception on the anomalous, compressed temporal decay of the density-density correlation functions observed in metallic glasses and many out-of-equilibrium soft materials.
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Submitted 22 March, 2024; v1 submitted 18 March, 2024;
originally announced March 2024.
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Unraveling the origin of antiferromagnetic coupling at YIG/permalloy interface
Authors:
Jiangchao Qian,
Yi Li,
Zhihao Jiang,
Robert Busch,
Hsu-Chih Ni,
Tzu-Hsiang Lo,
Axel Hoffmann,
André Schleife,
Jian-Min Zuo
Abstract:
We investigate the structural and electronic origin of antiferromagnetic (AFM) coupling in the Yttrium iron garnet (YIG) and permalloy (Py) bilayer system at the atomic level. Ferromagnetic Resonance (FMR) reveal unique hybrid modes in samples prepared with surface ion milling, indicative of antiferromagnetic exchange coupling at the YIG/Py interface. Using atomic resolution scanning transmission…
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We investigate the structural and electronic origin of antiferromagnetic (AFM) coupling in the Yttrium iron garnet (YIG) and permalloy (Py) bilayer system at the atomic level. Ferromagnetic Resonance (FMR) reveal unique hybrid modes in samples prepared with surface ion milling, indicative of antiferromagnetic exchange coupling at the YIG/Py interface. Using atomic resolution scanning transmission electron microscopy (STEM), we found that AFM coupling appears at the YIG/Py interface of the tetrahedral YIG surface formed with ion milling. The STEM measurements suggest that the interfacial AFM coupling is predominantly driven by an oxygen-mediated super-exchange coupling mechanism, which is confirmed by the density functional theory (DFT) calculations to be energetically favorable. Thus, the combined experimental and theoretical results reveal the critical role of interfacial atomic structure in determining the type magnetic coupling in a YIG/ferromagnet heterostructure, and prove that the interfacial structure can be experimentally tuned by surface ion-milling.
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Submitted 11 September, 2024; v1 submitted 22 February, 2024;
originally announced February 2024.
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Denser glasses relax faster: a competition between rejuvenation and aging during in-situ high pressure compression at the atomic scale
Authors:
A. Cornet,
G. Garbarino,
F. Zontone,
Y. Chushkin,
J. Jacobs,
E. Pineda,
T. Deschamps,
S. Li,
A. Ronca,
J. Shen,
G. Morard,
N. Neuber,
M. Frey,
R. Busch,
I. Gallino,
M. Mezouar,
G. Vaughan,
B. Ruta
Abstract:
A fascinating feature of metallic glasses is their ability to explore different configurations under mechanical deformations. This effect is usually observed through macroscopic observables, while little is known on the consequence of the deformation at atomic level. Using the new generation of synchrotrons, we probe the atomic motion and structure in a metallic glass under hydrostatic compression…
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A fascinating feature of metallic glasses is their ability to explore different configurations under mechanical deformations. This effect is usually observed through macroscopic observables, while little is known on the consequence of the deformation at atomic level. Using the new generation of synchrotrons, we probe the atomic motion and structure in a metallic glass under hydrostatic compression, from the onset of the perturbation up to a severely-compressed state. While the structure indicates reversible densification under compression, the dynamic is dramatically accelerated and exhibits a hysteresis with two regimes. At low pressures, the atomic motion is heterogeneous with avalanche-like rearrangements suggesting rejuvenation, while under further compression, aging leads to a super-diffusive dynamics triggered by internal stresses inherent to the glass. These results highlight the complexity of the atomic motion in non-ergodic systems and support a theory recently developed to describe the surprising rejuvenation and strain hardening of metallic glasses under compression.
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Submitted 6 January, 2023;
originally announced January 2023.
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Disentangling structural and kinetic components of the α-relaxation in supercooled metallic liquids
Authors:
Nico Neuber,
Oliver Gross,
Maximilian Frey,
Benedikt Bochtler,
Alexander Kuball,
Simon Hechler,
Fan Yang,
Eloi Pineda,
Fabian Westermeier,
Michael Sprung,
Isabella Gallino,
Ralf Busch,
Beatrice Ruta
Abstract:
The particle motion associated to the α-relaxation in supercooled liquids is still challenging scientists due to its difficulty to be probed experimentally. By combining synchrotron techniques, we found the existence of microscopic structure-dynamics relationships in Pt42.5Cu27Ni9.5P21 and Pd42.5Cu27Ni9.5P21 liquids which allows us to disentangle structural and kinetic contributions to the α-proce…
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The particle motion associated to the α-relaxation in supercooled liquids is still challenging scientists due to its difficulty to be probed experimentally. By combining synchrotron techniques, we found the existence of microscopic structure-dynamics relationships in Pt42.5Cu27Ni9.5P21 and Pd42.5Cu27Ni9.5P21 liquids which allows us to disentangle structural and kinetic contributions to the α-process. While the two alloys show similar kinetic fragilities, their structural fragilities differ and correlate with the temperature dependence of the stretching parameter describing the decay of the density fluctuations. This implies that the evolution of dynamical heterogeneities in supercooled alloys is determined by the rigidity of the melt structure. We find also that the atomic motion not only reflects the topological order but also the chemical short-range order, which can lead to a surprising slowdown of the α-process at the mesoscopic length scale. These results will contribute to the comprehension of the glass transition, which is still missing.
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Submitted 20 September, 2022;
originally announced September 2022.
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Wave vector dependence of the dynamics in supercooled metallic liquids
Authors:
B. Ruta,
S. Hechler,
N. Neuber,
D. Orsi,
L. Cristofolini,
O. Gross,
B. Bochtler,
M. Frey,
A. Kuball,
S. S. Riegler,
M. Stolpe,
Z. Evenson,
C. Gutt,
F. Westermeier,
R. Busch,
I. Gallino
Abstract:
We present a detailed investigation of the wave vector dependence of collective atomic motion in Au49Cu26.9Si16.3Ag5.5Pd2.3 and Pd42.5Cu27Ni9.5P21 supercooled liquids close to the glass transition temperature. Using x-ray photon correlation spectroscopy in a precedent uncovered spatial range of only few interatomic distances, we show that the microscopic structural relaxation process follows in ph…
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We present a detailed investigation of the wave vector dependence of collective atomic motion in Au49Cu26.9Si16.3Ag5.5Pd2.3 and Pd42.5Cu27Ni9.5P21 supercooled liquids close to the glass transition temperature. Using x-ray photon correlation spectroscopy in a precedent uncovered spatial range of only few interatomic distances, we show that the microscopic structural relaxation process follows in phase the structure with a marked slowing down at the main average inter-particle distance. This behavior is accompanied by dramatic changes in the shape of the intermediate scattering functions which suggest the presence of large dynamical heterogeneities at length-scales corresponding to few particle diameters. A ballistic-like mechanism of particle motion seems to govern the structural relaxation of the two systems in the highly viscous phase, likely associated to hopping of caged particles in agreement with theoretical studies.
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Submitted 28 August, 2020; v1 submitted 3 March, 2020;
originally announced March 2020.
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Liquid-liquid transition revealed by quasi-static cooling of an ultra-viscous metallic liquid
Authors:
S. Hechler,
B. Ruta,
M. Stolpe,
E. Pineda,
Z. Evenson,
O. Gross,
W. Hembree,
A. Bernasconi,
R. Busch,
I. Gallino
Abstract:
Temperature-driven polyamorphism has been reported in various supercooled liquids and glasses. The dynamical and structural routes followed by the system during such crossovers are however not universal and appear to be related to intrinsic kinetic properties of the liquid. By combining x-ray photon correlation spectroscopy and high energy x-ray diffraction, we have followed the collective atomic…
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Temperature-driven polyamorphism has been reported in various supercooled liquids and glasses. The dynamical and structural routes followed by the system during such crossovers are however not universal and appear to be related to intrinsic kinetic properties of the liquid. By combining x-ray photon correlation spectroscopy and high energy x-ray diffraction, we have followed the collective atomic motion and structural changes during quasi-static cooling of the Au49Cu26.9Si16.3Ag5.5Pd2.3 metallic glass-former. Due to this ultra-slow thermal protocol, the glass transition temperature is lowered far enough to reveal a liquid-liquid crossover in the ultra-viscous supercooled phase. This transition is usually hidden by vitrification and leads to a strong liquid characterized by increasing correlation at the medium range.
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Submitted 21 April, 2017;
originally announced April 2017.
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X-Ray Photon Correlation Spectroscopy Reveals Intermittent Aging Dynamics in a Metallic Glass
Authors:
Zach Evenson,
Beatrice Ruta,
Simon Hechler,
Moritz Stolpe,
Eloi Pineda,
Isabella Gallino,
Ralf Busch
Abstract:
We use coherent X-rays to probe the aging dynamics of a metallic glass directly on the atomic level. Contrary to the common assumption of a steady slowing down of the dynamics usually observed in macroscopic studies, we show that the structural relaxation processes underlying aging in this metallic glass are intermittent and highly heterogeneous at the atomic scale. Moreover, physical aging is tri…
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We use coherent X-rays to probe the aging dynamics of a metallic glass directly on the atomic level. Contrary to the common assumption of a steady slowing down of the dynamics usually observed in macroscopic studies, we show that the structural relaxation processes underlying aging in this metallic glass are intermittent and highly heterogeneous at the atomic scale. Moreover, physical aging is triggered by cooperative atomic rearrangements, driven by the relaxation of internal stresses. The rich diversity of this behavior reflects a complex energy landscape, giving rise to a unique type of glassy-state dynamics.
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Submitted 2 September, 2015;
originally announced September 2015.
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Thermodynamics, kinetics and fragility of bulk metallic glass forming liquids
Authors:
Ralf Busch,
Zach Evenson,
Isabella Gallino,
Shuai Wei
Abstract:
This review deals with the kinetic and thermodynamic fragility of bulk metallic glass forming liquids. The experimental methods to determine the kinetic fragility, relaxation behavior and thermodynamic functions of undercooled metallic liquids are introduced. Existing data are assessed and discussed using the Vogel-Fulcher-Tammann equation and in the frameworks of the Adam-Gibbs as well as the Coh…
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This review deals with the kinetic and thermodynamic fragility of bulk metallic glass forming liquids. The experimental methods to determine the kinetic fragility, relaxation behavior and thermodynamic functions of undercooled metallic liquids are introduced. Existing data are assessed and discussed using the Vogel-Fulcher-Tammann equation and in the frameworks of the Adam-Gibbs as well as the Cohen-Turnbull free volume approach. In contrast to pure metals and most non glass forming alloys, bulk glass formers are moderately strong liquids. In general the fragility parameter $D^{*} $ increases with the complexity of the alloy with differences between the alloy families, e.g. noble-metal based alloys being more fragile than Zr-based alloys. At least some bulk metallic glass forming liquids, such as Vitreloy 1, undergo transitions from a fragile state at high temperatures to a strong state at low temperatures with indications that in Zr-based alloys this behavior is a common phenomenon.
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Submitted 9 May, 2014;
originally announced May 2014.
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Obtaining Communities with a Fitness Growth Process
Authors:
Mariano G. Beiró,
Jorge R. Busch,
Sebastian P. Grynberg,
J. Ignacio Alvarez-Hamelin
Abstract:
The study of community structure has been a hot topic of research over the last years. But, while successfully applied in several areas, the concept lacks of a general and precise notion. Facts like the hierarchical structure and heterogeneity of complex networks make it difficult to unify the idea of community and its evaluation. The global functional known as modularity is probably the most used…
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The study of community structure has been a hot topic of research over the last years. But, while successfully applied in several areas, the concept lacks of a general and precise notion. Facts like the hierarchical structure and heterogeneity of complex networks make it difficult to unify the idea of community and its evaluation. The global functional known as modularity is probably the most used technique in this area. Nevertheless, its limits have been deeply studied. Local techniques as the ones by Lancichinetti et al. and Palla et al. arose as an answer to the resolution limit and degeneracies that modularity has.
Here we start from the algorithm by Lancichinetti et al. and propose a unique growth process for a fitness function that, while being local, finds a community partition that covers the whole network, updating the scale parameter dynamically. We test the quality of our results by using a set of benchmarks of heterogeneous graphs. We discuss alternative measures for evaluating the community structure and, in the light of them, infer possible explanations for the better performance of local methods compared to global ones in these cases.
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Submitted 6 June, 2012;
originally announced June 2012.
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On weakly optimal partitions in modular networks
Authors:
José Ignacio Alvarez-Hamelin,
Beiró Mariano Gastón,
Jorge Rodolfo Busch
Abstract:
Modularity was introduced as a measure of goodness for the community structure induced by a partition of the set of vertices in a graph. Then, it also became an objective function used to find good partitions, with high success. Nevertheless, some works have shown a scaling limit and certain instabilities when finding communities with this criterion. Modularity has been studied proposing several f…
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Modularity was introduced as a measure of goodness for the community structure induced by a partition of the set of vertices in a graph. Then, it also became an objective function used to find good partitions, with high success. Nevertheless, some works have shown a scaling limit and certain instabilities when finding communities with this criterion. Modularity has been studied proposing several formalisms, as hamiltonians in a Potts model or laplacians in spectral partitioning. In this paper we present a new probabilistic formalism to analyze modularity, and from it we derive an algorithm based on weakly optimal partitions. This algorithm obtains good quality partitions and also scales to large graphs.
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Submitted 20 August, 2010;
originally announced August 2010.