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Sidler D, Schnappinger T, Obzhirov A, Ruggenthaler M, Kowalewski M, Rubio A. Unraveling a Cavity-Induced Molecular Polarization Mechanism from Collective Vibrational Strong Coupling. J Phys Chem Lett 2024; 15:5208-5214. [PMID: 38717382 PMCID: PMC11103705 DOI: 10.1021/acs.jpclett.4c00913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/01/2024] [Accepted: 05/03/2024] [Indexed: 05/22/2024]
Abstract
We demonstrate that collective vibrational strong coupling of molecules in thermal equilibrium can give rise to significant local electronic polarizations in the thermodynamic limit. We do so by first showing that the full nonrelativistic Pauli-Fierz problem of an ensemble of strongly coupled molecules in the dilute-gas limit reduces in the cavity Born-Oppenheimer approximation to a cavity-Hartree equation for the electronic structure. Consequently, each individual molecule experiences a self-consistent coupling to the dipoles of all other molecules, which amount to non-negligible values in the thermodynamic limit (large ensembles). Thus, collective vibrational strong coupling can alter individual molecules strongly for localized "hotspots" within the ensemble. Moreover, the discovered cavity-induced polarization pattern possesses a zero net polarization, which resembles a continuous form of a spin glass (or better polarization glass). Our findings suggest that the thorough understanding of polaritonic chemistry, requires a self-consistent treatment of dressed electronic structure, which can give rise to numerous, so far overlooked, physical mechanisms.
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Affiliation(s)
- Dominik Sidler
- Laboratory
for Materials Simulations, Paul Scherrer
Institute, 5232 Villigen PSI, Switzerland
- Max
Planck Institute for the Structure and Dynamics of Matter and Center
for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
- The
Hamburg Center for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Thomas Schnappinger
- Department
of Physics, Stockholm University, AlbaNova University Center, SE-106
91 Stockholm, Sweden
| | - Anatoly Obzhirov
- Max
Planck Institute for the Structure and Dynamics of Matter and Center
for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
- The
Hamburg Center for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Michael Ruggenthaler
- Max
Planck Institute for the Structure and Dynamics of Matter and Center
for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
- The
Hamburg Center for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Markus Kowalewski
- Department
of Physics, Stockholm University, AlbaNova University Center, SE-106
91 Stockholm, Sweden
| | - Angel Rubio
- Max
Planck Institute for the Structure and Dynamics of Matter and Center
for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
- The
Hamburg Center for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
- Center
for Computational Quantum Physics, Flatiron
Institute, 162 Fifth Avenue, New York, New York 10010, United States
- Nano-Bio
Spectroscopy Group, University of the Basque
Country (UPV/EHU), 20018 San Sebastián, Spain
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2
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Meisenheimer P, Zhang H, Raftrey D, Chen X, Shao YT, Chan YT, Yalisove R, Chen R, Yao J, Scott MC, Wu W, Muller DA, Fischer P, Birgeneau RJ, Ramesh R. Ordering of room-temperature magnetic skyrmions in a polar van der Waals magnet. Nat Commun 2023; 14:3744. [PMID: 37353526 DOI: 10.1038/s41467-023-39442-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 06/13/2023] [Indexed: 06/25/2023] Open
Abstract
Control and understanding of ensembles of skyrmions is important for realization of future technologies. In particular, the order-disorder transition associated with the 2D lattice of magnetic skyrmions can have significant implications for transport and other dynamic functionalities. To date, skyrmion ensembles have been primarily studied in bulk crystals, or as isolated skyrmions in thin film devices. Here, we investigate the condensation of the skyrmion phase at room temperature and zero field in a polar, van der Waals magnet. We demonstrate that we can engineer an ordered skyrmion crystal through structural confinement on the μm scale, showing control over this order-disorder transition on scales relevant for device applications.
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Affiliation(s)
- Peter Meisenheimer
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA.
| | - Hongrui Zhang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA.
| | - David Raftrey
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Santa Cruz, CA, USA
| | - Xiang Chen
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
| | - Yu-Tsun Shao
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Ying-Ting Chan
- Department of Physics, Rutgers University, New Brunswick, NJ, USA
| | - Reed Yalisove
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Rui Chen
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Jie Yao
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
| | - Mary C Scott
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Weida Wu
- Department of Physics, Rutgers University, New Brunswick, NJ, USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA
| | - Peter Fischer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Santa Cruz, CA, USA
| | - Robert J Birgeneau
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, CA, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
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3
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O'Byrne J, Jerbi K. How critical is brain criticality? Trends Neurosci 2022; 45:820-837. [PMID: 36096888 DOI: 10.1016/j.tins.2022.08.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/27/2022] [Accepted: 08/10/2022] [Indexed: 10/31/2022]
Abstract
Criticality is the singular state of complex systems poised at the brink of a phase transition between order and randomness. Such systems display remarkable information-processing capabilities, evoking the compelling hypothesis that the brain may itself be critical. This foundational idea is now drawing renewed interest thanks to high-density data and converging cross-disciplinary knowledge. Together, these lines of inquiry have shed light on the intimate link between criticality, computation, and cognition. Here, we review these emerging trends in criticality neuroscience, highlighting new data pertaining to the edge of chaos and near-criticality, and making a case for the distance to criticality as a useful metric for probing cognitive states and mental illness. This unfolding progress in the field contributes to establishing criticality theory as a powerful mechanistic framework for studying emergent function and its efficiency in both biological and artificial neural networks.
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Affiliation(s)
- Jordan O'Byrne
- Cognitive and Computational Neuroscience Lab, Psychology Department, University of Montreal, Montreal, Quebec, Canada
| | - Karim Jerbi
- Cognitive and Computational Neuroscience Lab, Psychology Department, University of Montreal, Montreal, Quebec, Canada; MILA (Quebec Artificial Intelligence Institute), Montreal, Quebec, Canada; UNIQUE Center (Quebec Neuro-AI Research Center), Montreal, Quebec, Canada.
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4
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Jefremovas EM, Svedlindh P, Damay F, Alba Venero D, Michels A, Blanco JA, Fernández Barquín L. Magnetic order and disorder environments in superantiferromagnetic [Formula: see text] nanoparticles. Sci Rep 2022; 12:9733. [PMID: 35697857 PMCID: PMC9192703 DOI: 10.1038/s41598-022-13817-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 05/27/2022] [Indexed: 11/08/2022] Open
Abstract
Magnetic nanoparticles exhibit two different local symmetry environments, one ascribed to the core and one corresponding to the nanoparticle surface. This implies the existence of a dual spin dynamics, leading to the presence of two different magnetic arrangements governed by different correlation lengths. In this work, two ensembles of [Formula: see text] nanoparticles with mean sizes of 18 nm and 13 nm have been produced to unravel the magnetic couplings established among the magnetic moments located within the core and at the nanoparticle surface. To this end, we have combined neutron diffraction measurements, appropriate to investigate magnetically-ordered spin arrangements, with time-dependent macroscopic AC susceptibility measurements to reveal memory and aging effects. The observation of the latter phenomena are indicative of magnetically-frustrated states. The obtained results indicate that, while the [Formula: see text] magnetic moments located within the nanoparticle core keep the bulk antiferromagnetic commensurate structure in the whole magnetic state, the correlations among the surface spins give rise to a collective frustrated spin-glass phase. The interpretation of the magnetic structure of the nanoparticles is complemented by specific-heat measurements, which further support the lack of incommensurability in the nanoparticle state.
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Affiliation(s)
- E. M. Jefremovas
- Department CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain
| | - P. Svedlindh
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03 Uppsala, Sweden
| | - F. Damay
- Laboratoire Léon Brillouin, Université Paris–Saclay, CEA–CNRS, 91191 Gif–sur–Yvette Cedex, France
| | - D. Alba Venero
- ISIS Neutron and Muon Facility, Rutherford Appleton Laboratory, Didcot, OX11 0QX UK
| | - A. Michels
- Department of Physics and Materials Science, University of Luxembourg, 1511 Luxembourg, Luxembourg
| | - J. A. Blanco
- Department of Physics, University of Oviedo, 33007 Oviedo, Spain
| | - L. Fernández Barquín
- Department CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain
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5
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Koopmans L, Youk H. Predictive landscapes hidden beneath biological cellular automata. J Biol Phys 2021; 47:355-369. [PMID: 34739687 PMCID: PMC8603977 DOI: 10.1007/s10867-021-09592-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 10/14/2021] [Indexed: 11/11/2022] Open
Abstract
To celebrate Hans Frauenfelder's achievements, we examine energy(-like) "landscapes" for complex living systems. Energy landscapes summarize all possible dynamics of some physical systems. Energy(-like) landscapes can explain some biomolecular processes, including gene expression and, as Frauenfelder showed, protein folding. But energy-like landscapes and existing frameworks like statistical mechanics seem impractical for describing many living systems. Difficulties stem from living systems being high dimensional, nonlinear, and governed by many, tightly coupled constituents that are noisy. The predominant modeling approach is devising differential equations that are tailored to each living system. This ad hoc approach faces the notorious "parameter problem": models have numerous nonlinear, mathematical functions with unknown parameter values, even for describing just a few intracellular processes. One cannot measure many intracellular parameters or can only measure them as snapshots in time. Another modeling approach uses cellular automata to represent living systems as discrete dynamical systems with binary variables. Quantitative (Hamiltonian-based) rules can dictate cellular automata (e.g., Cellular Potts Model). But numerous biological features, in current practice, are qualitatively described rather than quantitatively (e.g., gene is (highly) expressed or not (highly) expressed). Cellular automata governed by verbal rules are useful representations for living systems and can mitigate the parameter problem. However, they can yield complex dynamics that are difficult to understand because the automata-governing rules are not quantitative and much of the existing mathematical tools and theorems apply to continuous but not discrete dynamical systems. Recent studies found ways to overcome this challenge. These studies either discovered or suggest an existence of predictive "landscapes" whose shapes are described by Lyapunov functions and yield "equations of motion" for a "pseudo-particle." The pseudo-particle represents the entire cellular lattice and moves on the landscape, thereby giving a low-dimensional representation of the cellular automata dynamics. We outline this promising modeling strategy.
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Affiliation(s)
- Lars Koopmans
- Program in Applied Physics, Delft University of Technology, Delft, The Netherlands
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Hyun Youk
- Department of Systems Biology, University of Massachusetts Chan Medical School, Worcester, MA, USA.
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6
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Pal S, Banerjee A. Finite size effect on the magnetic glass. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:035801. [PMID: 34607321 DOI: 10.1088/1361-648x/ac2ca8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 10/04/2021] [Indexed: 06/13/2023]
Abstract
The nature of glass formation and crystallization in structural glass is yet to be understood despite the intense studies of many decades. Analogous to the structural glasses, hindered first order magnetic transitions produce magnetic glasses, where the volume fraction of two phases having long range structural and magnetic order are frozen in time. Here, we have prepared Pr0.5Ca0.5Mn0.975Al0.025O3nanoparticles of different size as a case study and investigated the formation and stability of the magnetic glass state at the length scale of a few nanometers. We have observed a profound interplay between the glass state and sample size: stability of the glass state highly increases and scales linearly with decrease in the sample size. Smaller the particle size, slower is the crystallization rate. The crystallization occurs through both homogeneous and heterogeneous nucleation and is controlled by the surface to volume ratio of the particles. Our results emphasize on an important fact that glass transition is not a phase transition in actual sense, rather it is a kinetic phenomena. The length scale associated with different nucleation processes is an important length scale and it controls the glass dynamics. Besides, apart from the intrinsic metastability due to magnetic glass, we also distinguish a secondary source of relaxation, which is dominant at low magnetic fields, predominantly arising due to surface spin disorder.
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Affiliation(s)
- Sudip Pal
- UGC DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001, India
| | - A Banerjee
- UGC DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001, India
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7
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Altieri A, Roy F, Cammarota C, Biroli G. Properties of Equilibria and Glassy Phases of the Random Lotka-Volterra Model with Demographic Noise. PHYSICAL REVIEW LETTERS 2021; 126:258301. [PMID: 34241496 DOI: 10.1103/physrevlett.126.258301] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 02/06/2021] [Accepted: 05/17/2021] [Indexed: 06/13/2023]
Abstract
We study a reference model in theoretical ecology, the disordered Lotka-Volterra model for ecological communities, in the presence of finite demographic noise. Our theoretical analysis, valid for symmetric interactions, shows that for sufficiently heterogeneous interactions and low demographic noise the system displays a multiple equilibria phase, which we fully characterize. In particular, we show that in this phase the number of locally stable equilibria is exponential in the number of species. Upon further decreasing the demographic noise, we unveil the presence of a second transition like the so-called "Gardner" transition to a marginally stable phase similar to that observed in the jamming of amorphous materials. We confirm and complement our analytical results by numerical simulations. Furthermore, we extend their relevance by showing that they hold for other interacting random dynamical systems such as the random replicant model. Finally, we discuss their extension to the case of asymmetric couplings.
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Affiliation(s)
- Ada Altieri
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris F-75005 Paris, France
- Laboratoire Matière et Systèmes Complexes (MSC), Université de Paris & CNRS, 75013 Paris, France
| | - Felix Roy
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris F-75005 Paris, France
- Institut de physique théorique, Université Paris Saclay, CEA, CNRS, F-91191 Gif-sur-Yvette, France
| | - Chiara Cammarota
- Dipartimento di Fisica, Universitá "Sapienza," Piazzale A. Moro 2, I-00185 Rome, Italy
- Department of Mathematics, King's College London, Strand London WC2R 2LS, United Kingdom
| | - Giulio Biroli
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris F-75005 Paris, France
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8
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Pal S, Kumar K, Banerjee A, Roy SB, Nigam AK. Non-equilibrium magnetic response of canonical spin glass and magnetic glass. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:025801. [PMID: 32927441 DOI: 10.1088/1361-648x/abb865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Time and history dependent magnetization has been observed in a wide variety of materials, which are collectively termed as the glassy magnetic systems. However, such systems showing similar non-equilibrium magnetic response can be microscopically very different and they can be distinguished by carefully looking into the details of the observed metastable magnetic behavior. Canonical spin glass (SG) is the most well studied member of this class and has been extensively investigated both experimentally and theoretically over the last five decades. In canonical SGs, the low temperature magnetic state obtained by cooling across the SG transition temperature in presence of an applied magnetic field is known as the field cooled (FC) state. This FC state in canonical SG is widely believed as an equilibrium state arising out of a thermodynamic second order phase transition. Here, we show that the FC state in canonical SG is not really an equilibrium state of the system. We report careful dc magnetization and ac susceptibility measurements on two canonical SG systems, AuMn (1.8%) and AgMn (1.1%). The dc magnetization in the FC state shows clear temperature dependence. In addition, the magnetization shows a distinct thermal hysteresis in the temperature regime below the SG transition temperature. On the other hand, the temperature dependence of ac susceptibility has clear frequency dispersion below SG transition in the FC state prepared by cooling the sample in the presence of a dc-bias field. We further distinguish the metastable response of the FC state of canonical SG from the metastable response of the FC state in an entirely different class of glassy magnetic system namely magnetic glass, where the non-equilibrium behavior is associated with the kinetic-arrest of a first order magnetic phase transition.
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Affiliation(s)
- Sudip Pal
- UGC DAE Consortium for Scientific Research, Indore-452001, India
| | - Kranti Kumar
- UGC DAE Consortium for Scientific Research, Indore-452001, India
| | - A Banerjee
- UGC DAE Consortium for Scientific Research, Indore-452001, India
| | - S B Roy
- UGC DAE Consortium for Scientific Research, Indore-452001, India
| | - A K Nigam
- Tata Institute of Fundamental Research, Mumbai-400005, India
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9
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Vázquez P, Petelczyc M, Hristovski R, Balagué N. Interlimb Coordination: A New Order Parameter and a Marker of Fatigue During Quasi-Isometric Exercise? Front Physiol 2021; 11:612709. [PMID: 33510649 PMCID: PMC7835426 DOI: 10.3389/fphys.2020.612709] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 12/04/2020] [Indexed: 11/24/2022] Open
Abstract
Although exercise-induced fatigue has been mostly studied from a reductionist and component-dominant approach, some authors have started to test the general predictions of theories of self-organized change during exercises performed until exhaustion. However, little is known about the effects of fatigue on interlimb coordination in quasi-isometric actions. The aim of this study was to investigate the effect of exercise-induced fatigue on upper interlimb coordination during a quasi-isometric exercise performed until exhaustion. In order to do this, we hypothesized an order parameter that governs the interlimb coordination as an interlimb correlation measure. In line with general predictions of theory of phase transitions, we expected that the locally averaged values of the order parameter will increase as the fatigue driven system approaches the point of spontaneous task disengagement. Seven participants performed a quasi-isometric task holding an Olympic bar maintaining an initial elbow flexion of 90 degrees until fatigue induced spontaneous task disengagement. The variability of the elbow angle was recorded through electrogoniometry and the obtained time series were divided into three segments for further analysis. Running correlation function (RCF) and adopted bivariate phase rectified signal averaging (BPRSA) were applied to the corresponding initial (30%) and last (30%) segments of the time series. The results of both analyses showed that the interlimb correlation increased between the initial and the final segments of the performed task. Hence, the hypothesis of the research was supported by evidence. The enhancement of the correlation in the last part means a less flexible coordination among limbs. Our results also show that the high magnitude correlation (%RCF > 0.8) and the %Range (END-BEG) may prove to be useful markers to detect the effects of effort accumulation on interlimb coordination. These results may provide information about the loss of adaptability during exercises performed until exhaustion. Finally, we briefly discuss the hypothesis of the inhibitory percolation process being the general explanation of the spontaneous task disengagement phenomenon.
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Affiliation(s)
- Pablo Vázquez
- Complex Systems in Sport Research Group, Institut Nacional d’Educació Física de Catalunya (INEFC), Universitat de Barcelona, Barcelona, Spain
| | - Monika Petelczyc
- Cardiovascular Physics Group, Faculty of Physics, Warsaw University of Technology, Warsaw, Poland
| | - Robert Hristovski
- Complex Systems in Sport Research Group, Faculty of Physical Education, Sport and Health, Ss. Cyril and Methodius University in Skopje, Skopje, North Macedonia
| | - Natàlia Balagué
- Complex Systems in Sport Research Group, Institut Nacional d’Educació Física de Catalunya (INEFC), Universitat de Barcelona, Barcelona, Spain
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10
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Hantanasirisakul K, Anasori B, Nemsak S, Hart JL, Wu J, Yang Y, Chopdekar RV, Shafer P, May AF, Moon EJ, Zhou J, Zhang Q, Taheri ML, May SJ, Gogotsi Y. Evidence of a magnetic transition in atomically thin Cr 2TiC 2T x MXene. NANOSCALE HORIZONS 2020; 5:1557-1565. [PMID: 33089267 DOI: 10.1039/d0nh00343c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Two-dimensional (2D) transition metal carbides and nitrides known as MXenes have shown attractive functionalities such as high electronic conductivity, a wide range of optical properties, versatile transition metal and surface chemistry, and solution processability. Although extensively studied computationally, the magnetic properties of this large family of 2D materials await experimental exploration. 2D magnetic materials have recently attracted significant interest as model systems to understand low-dimensional magnetism and for potential spintronic applications. Here, we report on synthesis of Cr2TiC2Tx MXene and a detailed study of its magnetic as well as electronic properties. Using a combination of magnetometry, synchrotron X-ray linear dichroism, and field- and angular-dependent magnetoresistance measurements, we find clear evidence of a magnetic transition in Cr2TiC2Tx at approximately 30 K, which is not present in its bulk layered carbide counterpart (Cr2TiAlC2 MAX phase). This work presents the first experimental evidence of a magnetic transition in a MXene material and provides an exciting opportunity to explore magnetism in this large family of 2D materials.
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11
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Nepal R, Wang Z, Dai S, Saghayezhian M, Zhu Y, Plummer EW, Jin R. Emergent Spin Glass Behavior Created by Self-Assembled Antiferromagnetic NiO Columns in Ferrimagnetic NiFe 2O 4. ACS APPLIED MATERIALS & INTERFACES 2020; 12:38788-38795. [PMID: 32805899 DOI: 10.1021/acsami.0c10790] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Spin glass (SG) is a magnetic state with spin structure incommensurate with lattice and charge. Fundamental understanding of its behavior has a profound impact on many technological problems. Here, we present a novel case of interface-induced spin glass behavior via self-assembly of single-crystalline NiO microcolumns in a single-crystalline NiFe2O4 matrix. Scanning transmission electron microscopy indicates that the hexagonal-shaped NiO columns are along their [211] direction and oriented along the [111] direction of the NiFe2O4 matrix. Magnetic force microscopy reveals magnetic anisotropy between NiO columns (antiferromagnetic transition temperature TN ∼ 523 K) and NiFe2O4 matrix (ferrimagnetic transition temperature TFI ∼ 860 K). This leads to spin disorder/frustration at atomically sharp NiFe2O4/NiO interfaces responsible for spin glass behavior below TSG ∼ 28 K. Our results demonstrate that self-assembly of magnetically distinct microstructures into another crystalline and magnetically ordered matrix is an effective way to create novel spin states at interfaces.
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Affiliation(s)
- Roshan Nepal
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Zhen Wang
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Samuel Dai
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Mohammad Saghayezhian
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Yimei Zhu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - E Ward Plummer
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Rongying Jin
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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12
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Nahas Y, Prokhorenko S, Fischer J, Xu B, Carrétéro C, Prosandeev S, Bibes M, Fusil S, Dkhil B, Garcia V, Bellaiche L. Inverse transition of labyrinthine domain patterns in ferroelectric thin films. Nature 2020; 577:47-51. [DOI: 10.1038/s41586-019-1845-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 09/10/2019] [Indexed: 11/09/2022]
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13
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Spin Glasses: Experimental Signatures and Salient Outcomes. FRUSTRATED MATERIALS AND FERROIC GLASSES 2018. [DOI: 10.1007/978-3-319-96914-5_2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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14
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15
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Tommasi F, Ignesti E, Lepri S, Cavalieri S. Robustness of replica symmetry breaking phenomenology in random laser. Sci Rep 2016; 6:37113. [PMID: 27849029 PMCID: PMC5111062 DOI: 10.1038/srep37113] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 10/25/2016] [Indexed: 11/09/2022] Open
Abstract
Random lasers are optical sources where light is amplified by stimulated emission along random paths through an amplifying scattering medium. Connections between their physics and the one of quenched disordered nonlinear systems, notably spin glasses, have been recently suggested. Here we report a first experimental study of correlations of spectral fluctuations intensity in a random laser medium where the scatterers displacement significantly changes among consecutive shots. Remarkably, our results reveal that the replica symmetry breaking (RSB) phenomenology is robust with respect to an averaging over different realizations of the disorder. Moreover, besides opening new intriguing questions about the understanding of such a phenomenon, this work aims to clarify the connection between the RSB with the onset of the Lévy regime, i.e. the fluctuations regime that is a peculiar feature of the random lasing under critical conditions. Our results suggest that the former occurs independently of the latter and then the RSB phenomenology is a generic feature linked to the random laser threshold.
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Affiliation(s)
- Federico Tommasi
- Dipartimento di Fisica e Astronomia, Università di Firenze, Via G. Sansone 1 I-50019 Sesto Fiorentino, Italy
| | - Emilio Ignesti
- Dipartimento di Fisica e Astronomia, Università di Firenze, Via G. Sansone 1 I-50019 Sesto Fiorentino, Italy
| | - Stefano Lepri
- Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - Stefano Cavalieri
- Dipartimento di Fisica e Astronomia, Università di Firenze, Via G. Sansone 1 I-50019 Sesto Fiorentino, Italy
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Požar M, Kerasidou A, Lovrinčević B, Zoranić L, Mijaković M, Primorac T, Sokolić F, Teboul V, Perera A. The microscopic structure of cold aqueous methanol mixtures. J Chem Phys 2016; 145:144502. [DOI: 10.1063/1.4964487] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Antenucci F, Crisanti A, Leuzzi L. The glassy random laser: replica symmetry breaking in the intensity fluctuations of emission spectra. Sci Rep 2015; 5:16792. [PMID: 26616194 PMCID: PMC4663759 DOI: 10.1038/srep16792] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 10/16/2015] [Indexed: 11/09/2022] Open
Abstract
The behavior of a newly introduced overlap parameter, measuring the correlation between intensity fluctuations of waves in random media, is analyzed in different physical regimes, with varying amount of disorder and non-linearity. This order parameter allows to identify the laser transition in random media and describes its possible glassy nature in terms of emission spectra data, the only data so far accessible in random laser measurements. The theoretical analysis is performed in terms of the complex spherical spin-glass model, a statistical mechanical model describing the onset and the behavior of random lasers in open cavities. Replica Symmetry Breaking theory allows to discern different kinds of randomness in the high pumping regime, including the most complex and intriguing glassy randomness. The outcome of the theoretical study is, eventually, compared to recent intensity fluctuation overlap measurements demonstrating the validity of the theory and providing a straightforward interpretation of qualitatively different spectral behaviors in different random lasers.
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Affiliation(s)
- Fabrizio Antenucci
- NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, Rome, Piazzale A. Moro 2, I-00185, Roma, Italy
- Dipartimento di Fisica, Università di Roma “Sapienza”, Piazzale A. Moro 2, I-00185, Roma, Italy
| | - Andrea Crisanti
- Dipartimento di Fisica, Università di Roma “Sapienza”, Piazzale A. Moro 2, I-00185, Roma, Italy
- ISC-CNR, UOS Sapienza, Piazzale A. Moro 2, I-00185, Roma, Italy
| | - Luca Leuzzi
- NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, Rome, Piazzale A. Moro 2, I-00185, Roma, Italy
- Dipartimento di Fisica, Università di Roma “Sapienza”, Piazzale A. Moro 2, I-00185, Roma, Italy
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Almeida STO, Nobre FD. Critical properties of short-range Ising spin glasses on a Wheatstone-bridge hierarchical lattice. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:022102. [PMID: 26382339 DOI: 10.1103/physreve.92.022102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Indexed: 06/05/2023]
Abstract
An Ising spin-glass model with nearest-neighbor interactions, following a symmetric probability distribution, is investigated on a hierarchical lattice of the Wheatstone-bridge family characterized by a fractal dimension D≈3.58. The interaction distribution considered is a stretched exponential, which has been shown recently to be very close to the fixed-point coupling distribution, and such a model has been considered lately as a good approach for Ising spin glasses on a cubic lattice. An exact recursion procedure is implemented for calculating site magnetizations, mi=〈Si〉T, as well as correlations between pairs of nearest-neighbor spins, 〈SiSj〉T (〈〉T denote thermal averages), for a given set of interaction couplings on this lattice. From these local magnetizations and correlations, one can compute important physical quantities, such as the Edwards-Anderson order parameter, the internal energy, and the specific heat. Considering extrapolations to the thermodynamic limit for the order parameter, such as a finite-size scaling approach, it is possible to obtain directly the critical temperature and critical exponents. The transition between the spin-glass and paramagnetic phases is analyzed, and the associated critical exponents β and ν are estimated as β=0.82(5) and ν=2.50(4), which are in good agreement with the most recent results from extensive numerical simulations on a cubic lattice. Since these critical exponents were obtained from a fixed-point distribution, they are universal, i.e., valid for any coupling distribution considered.
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Affiliation(s)
- Sebastião T O Almeida
- Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro RJ, Brazil
- Colégio Técnico da Universidade Federal Rural do Rio de Janeiro, Seropédica, 23891-000 Rio de Janeiro RJ, Brazil
| | - Fernando D Nobre
- Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro RJ, Brazil
- National Institute of Science and Technology for Complex Systems, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro RJ, Brazil
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Almeida STO, Nobre FD. Fixed-point distributions of short-range Ising spin glasses on hierarchical lattices. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:032138. [PMID: 25871085 DOI: 10.1103/physreve.91.032138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Indexed: 06/04/2023]
Abstract
Fixed-point distributions for the couplings of Ising spin glasses with nearest-neighbor interactions on hierarchical lattices are investigated numerically. Hierarchical lattices within the Migdal-Kadanoff family with fractal dimensions in the range 2.58≤D≤7, as well as a lattice of the Wheatstone-Bridge family with fractal dimension D≈3.58 are considered. Three initial distributions for the couplings are analyzed, namely, the Gaussian, bimodal, and uniform ones. In all cases, after a few iterations of the renormalization-group procedure, the associated probability distributions approached universal fixed shapes. For hierarchical lattices of the Migdal-Kadanoff family, the fixed-point distributions were well fitted either by stretched exponentials, or by q-Gaussian distributions; both fittings recover the expected Gaussian limit as D→∞. In the case of the Wheatstone-Bridge lattice, the best fit was found by means of a stretched-exponential distribution.
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Affiliation(s)
- Sebastião T O Almeida
- Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ, Brazil
- Colégio Técnico da Universidade Federal Rural do Rio de Janeiro, Seropédica, 23891-000 Rio de Janeiro, RJ, Brazil
| | - Fernando D Nobre
- Centro Brasileiro de Pesquisas Físicas, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ, Brazil
- National Institute of Science and Technology for Complex Systems, Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ, Brazil
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Evolution and selection of river networks: statics, dynamics, and complexity. Proc Natl Acad Sci U S A 2014; 111:2417-24. [PMID: 24550264 DOI: 10.1073/pnas.1322700111] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Moving from the exact result that drainage network configurations minimizing total energy dissipation are stationary solutions of the general equation describing landscape evolution, we review the static properties and the dynamic origins of the scale-invariant structure of optimal river patterns. Optimal channel networks (OCNs) are feasible optimal configurations of a spanning network mimicking landscape evolution and network selection through imperfect searches for dynamically accessible states. OCNs are spanning loopless configurations, however, only under precise physical requirements that arise under the constraints imposed by river dynamics--every spanning tree is exactly a local minimum of total energy dissipation. It is remarkable that dynamically accessible configurations, the local optima, stabilize into diverse metastable forms that are nevertheless characterized by universal statistical features. Such universal features explain very well the statistics of, and the linkages among, the scaling features measured for fluvial landforms across a broad range of scales regardless of geology, exposed lithology, vegetation, or climate, and differ significantly from those of the ground state, known exactly. Results are provided on the emergence of criticality through adaptative evolution and on the yet-unexplored range of applications of the OCN concept.
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Apostolico A, Comin M, Dress A, Parida L. Ultrametric networks: a new tool for phylogenetic analysis. Algorithms Mol Biol 2013; 8:7. [PMID: 23497437 PMCID: PMC3693977 DOI: 10.1186/1748-7188-8-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 02/18/2013] [Indexed: 05/27/2023] Open
Abstract
Background The large majority of optimization problems related to the inference of distance‐based trees used in phylogenetic analysis and classification is known to be intractable. One noted exception is found within the realm of ultrametric distances. The introduction of ultrametric trees in phylogeny was inspired by a model of evolution driven by the postulate of a molecular clock, now dismissed, whereby phylogeny could be represented by a weighted tree in which the sum of the weights of the edges separating any given leaf from the root is the same for all leaves. Both, molecular clocks and rooted ultrametric trees, fell out of fashion as credible representations of evolutionary change. At the same time, ultrametric dendrograms have shown good potential for purposes of classification in so far as they have proven to provide good approximations for additive trees. Most of these approximations are still intractable, but the problem of finding the nearest ultrametric distance matrix to a given distance matrix with respect to the L∞ distance has been long known to be solvable in polynomial time, the solution being incarnated in any minimum spanning tree for the weighted graph subtending to the matrix. Results This paper expands this subdominant ultrametric perspective by studying ultrametric networks, consisting of the collection of all edges involved in some minimum spanning tree. It is shown that, for a graph with n vertices, the construction of such a network can be carried out by a simple algorithm in optimal time O(n2) which is faster by a factor of n than the direct adaptation of the classical O(n3) paradigm by Warshall for computing the transitive closure of a graph. This algorithm, called UltraNet, will be shown to be easily adapted to compute relaxed networks and to support the introduction of artificial points to reduce the maximum distance between vertices in a pair. Finally, a few experiments will be discussed to demonstrate the applicability of subdominant ultrametric networks. Availability http://www.dei.unipd.it/~ciompin/main/Ultranet/Ultranet.html
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Gommes CJ, Jiao Y, Torquato S. Microstructural degeneracy associated with a two-point correlation function and its information content. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:051140. [PMID: 23004736 DOI: 10.1103/physreve.85.051140] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Indexed: 06/01/2023]
Abstract
A two-point correlation function provides a crucial yet an incomplete characterization of a microstructure because distinctly different microstructures may have the same correlation function. In an earlier Letter [Gommes, Jiao, and Torquato, Phys. Rev. Lett. 108, 080601 (2012)], we addressed the microstructural degeneracy question: What is the number of microstructures compatible with a specified correlation function? We computed this degeneracy, i.e., configurational entropy, in the framework of reconstruction methods, which enabled us to map the problem to the determination of ground-state degeneracies. Here, we provide a more comprehensive presentation of the methodology and analyses, as well as additional results. Since the configuration space of a reconstruction problem is a hypercube on which a Hamming distance is defined, we can calculate analytically the energy profile of any reconstruction problem, corresponding to the average energy of all microstructures at a given Hamming distance from a ground state. The steepness of the energy profile is a measure of the roughness of the energy landscape associated with the reconstruction problem, which can be used as a proxy for the ground-state degeneracy. The relationship between this roughness metric and the ground-state degeneracy is calibrated using a Monte Carlo algorithm for determining the ground-state degeneracy of a variety of microstructures, including realizations of hard disks and Poisson point processes at various densities as well as those with known degeneracies (e.g., single disks of various sizes and a particular crystalline microstructure). We show that our results can be expressed in terms of the information content of the two-point correlation functions. From this perspective, the a priori condition for a reconstruction to be accurate is that the information content, expressed in bits, should be comparable to the number of pixels in the unknown microstructure. We provide a formula to calculate the information content of any two-point correlation function, which makes our results broadly applicable to any field in which correlation functions are employed.
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Affiliation(s)
- C J Gommes
- Department of Chemical Engineering, University of Liège, Liège 4000, Belgium.
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Gommes CJ, Jiao Y, Torquato S. Density of States for a specified correlation function and the energy landscape. PHYSICAL REVIEW LETTERS 2012; 108:080601. [PMID: 22463509 DOI: 10.1103/physrevlett.108.080601] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Indexed: 05/31/2023]
Abstract
The degeneracy of two-phase disordered microstructures consistent with a specified correlation function is analyzed by mapping it to a ground-state degeneracy. We determine for the first time the associated density of states via a Monte Carlo algorithm. Our results are explained in terms of the roughness of an energy landscape, defined on a hypercubic configuration space. The use of a Hamming distance in this space enables us to define a roughness metric, which is calculated from the correlation function alone and related quantitatively to the structural degeneracy. This relation is validated for a wide variety of disordered structures.
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Affiliation(s)
- C J Gommes
- Department of Chemical Engineering, University of Liège, B-4000 Liège, Belgium.
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Boulougouris GC. On the Estimation of the Free Energy, From a Single Equilibrium Statistical Ensemble, via Particle Reinsertion. J Phys Chem B 2012; 116:997-1006. [DOI: 10.1021/jp2036185] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Georgios C. Boulougouris
- Department of Molecular Biology and Genetics, Democritius University, 68100, Alexandroupolis, Greece, and Scienomics SARL, 17, Square Edouard VII, 75009 Paris, France
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25
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Zhou Q. Random walk over basins of attraction to construct ising energy landscapes. PHYSICAL REVIEW LETTERS 2011; 106:180602. [PMID: 21635078 DOI: 10.1103/physrevlett.106.180602] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Indexed: 05/30/2023]
Abstract
An efficient algorithm is developed to construct disconnectivity graphs by a random walk over basins of attraction. This algorithm can detect a large number of local minima, find energy barriers between them, and estimate local thermal averages over each basin of attraction. It is applied to the Sherrington-Kirkpatrick (SK) spin glass Hamiltonian where existing methods have difficulties even for a moderate number of spins. Finite-size results are used to make predictions in the thermodynamic limit that match theoretical approximations and recent findings on the free energy landscapes of SK spin glasses.
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Affiliation(s)
- Qing Zhou
- Department of Statistics, University of California, Los Angeles, 90095, USA
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