scholarly journals Fractional Power-Law Intraband Optical Conductivity in the Low-Dimensional Dirac Material CaMnBi2

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 428
Author(s):  
M. B. Schilling ◽  
C. X. Wang ◽  
Y. G. Shi ◽  
R. K. Kremer ◽  
M. Dressel ◽  
...  
Keyword(s):  
Power Law ◽  
Optical Conductivity ◽  
Low Temperatures ◽  
Fractional Power ◽  
Electronic System ◽  
Quantum Criticality ◽  
Free Carriers ◽  
Universal Power Law ◽  
Low Dimensional ◽  
Open Question

We studied the broadband optical conductivity of CaMnBi2, a material with two-dimensional Dirac electronic bands, and found that both components of the intraband conductivity follow a universal power law as a function of frequency at low temperatures. This conductivity scaling differs from the Drude(-like) behavior, generally expected for free carriers, but matches the predictions for the intraband response of an electronic system in a quantum critical region. Since no other indications of quantum criticality are reported for CaMnBi2 so far, the cause of the observed unusual scaling remains an open question.

scholarly journals Maximal modularity and the optimal size of parliaments

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luca Gamberi ◽  
Yanik-Pascal Förster ◽  
Evan Tzanis ◽  
Alessia Annibale ◽  
Pierpaolo Vivo
Keyword(s):  
Power Law ◽  
Real World ◽  
Empirical Data ◽  
Random Network ◽  
Functional Relation ◽  
Optimal Size ◽  
Real World Data ◽  
Universal Power Law ◽  
The Empirical Analysis ◽  
Democratic Country

AbstractAn important question in representative democracies is how to determine the optimal parliament size of a given country. According to an old conjecture, known as the cubic root law, there is a fairly universal power-law relation, with an exponent equal to 1/3, between the size of an elected parliament and the country’s population. Empirical data in modern European countries support such universality but are consistent with a larger exponent. In this work, we analyse this intriguing regularity using tools from complex networks theory. We model the population of a democratic country as a random network, drawn from a growth model, where each node is assigned a constituency membership sampled from an available set of size D. We calculate analytically the modularity of the population and find that its functional relation with the number of constituencies is strongly non-monotonic, exhibiting a maximum that depends on the population size. The criterion of maximal modularity allows us to predict that the number of representatives should scale as a power-law in the size of the population, a finding that is qualitatively confirmed by the empirical analysis of real-world data.

Effect of Adsorbed Water and Temperature on the Universal Power Law Behavior of Lepidocrocite-Type Alkali Titanate Ceramics

2021 ◽  
Author(s):  
Saichon Sriphan ◽  
Phieraya Pulphol ◽  
Thitirat Charoonsuk ◽  
Tosapol Maluangnont ◽  
Naratip Vittayakorn
Keyword(s):  
Power Law ◽  
Adsorbed Water ◽  
Universal Power Law ◽  
Titanate Ceramics

Quantum Criticality and Collective Effects in Low-Dimensional Magnet CuGeO3:Fe Probed by High Frequency EPR

2006 ◽  
Vol 20 (2) ◽  
pp. 105-108 ◽  
Author(s):  
S. V. Demishev ◽  
A. V. Semeno ◽  
A. A. Pronin ◽  
N. E. Sluchanko ◽  
N. A. Samarin ◽  
...  
Keyword(s):  
High Frequency ◽  
Quantum Criticality ◽  
Collective Effects ◽  
Low Dimensional

93Nb Nuclear Spin-Spin Relaxation in the Low-Dimensional Antiferromagnet Fe0.25NbS2

2007 ◽  
Vol 62 (10-11) ◽  
pp. 627-632
Author(s):  
Noriaki Okubo
Keyword(s):  
Temperature Dependence ◽  
Spin Relaxation ◽  
Nuclear Spin ◽  
Low Temperatures ◽  
Fast Decay ◽  
Low Dimensional

93Nb nuclear spin-spin relaxation has been examined in the low-dimensional antiferromagnet Fe0.25NbS2 between 4.2 K and 300 K. The relaxation is characterized by two T2’s. The temperature dependence is discussed together with the origin of the disappearance of the fast decay at low temperatures.

A universal power law and proportionate change process characterize the evolution of metabolic networks

2007 ◽  
Vol 57 (1) ◽  
pp. 75-80 ◽  
Author(s):  
S. Singh ◽  
A. Samal ◽  
V. Giri ◽  
S. Krishna ◽  
N. Raghuram ◽  
...  
Keyword(s):  
Power Law ◽  
Change Process ◽  
Metabolic Networks ◽  
Universal Power Law ◽  
Proportionate Change

AC Loss Modeling in Ba0.5Sr0.5TiO3 Using Dielectric Relaxation

2004 ◽  
Vol 833 ◽  
Author(s):  
Nadia K. Pervez ◽  
Jiwei Lu ◽  
Susanne Stemmer ◽  
Robert A. York
Keyword(s):  
Dielectric Loss ◽  
Dielectric Relaxation ◽  
Power Law ◽  
Fractional Power ◽  
Ac Loss ◽  
Dielectric Susceptibility ◽  
Network Analyzer ◽  
Q Factor ◽  
Relaxation Model ◽  
Q Factors

ABSTRACTIn universal relaxation, a material's complex dielectric susceptibility follows a fractional power law f1-n where 0 < n < 1 over multiple decades of frequency. In a variety of materials, including Ba0.5Sr0.5Ti03, dielectric relaxation has been observed to follow this universal relaxation model with values of n close to 1. In this work we have shown that the universal relaxation model can be used to calculate dielectric loss even when n is very close to 1. Our calculated Q-factors agree with measured values at 1 MHz; this agreement suggests that this technique may be used for higher frequencies where network analyzer measurements and electrode parasitics complicate Q-factor determination.

The fractional power law of wind wave growth in deep water for short fetch

2002 ◽  
Vol 1 (2) ◽  
pp. 105-108 ◽  
Author(s):  
Guan Changlong ◽  
Sun Qun ◽  
Philippe Fraunie
Keyword(s):  
Power Law ◽  
Deep Water ◽  
Wind Wave ◽  
Fractional Power ◽  
Wave Growth
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