scholarly journals Catastrophe theory classification of Fermi surface topological transitions in two dimensions

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Anirudh Chandrasekaran ◽  
Alex Shtyk ◽  
Joseph J. Betouras ◽  
Claudio Chamon
Keyword(s):  
Fermi Surface ◽  
Catastrophe Theory ◽  
Two Dimensions ◽  
Topological Transitions

scholarly journals Fermi surface reconstruction and multiple quantum phase transitions in the antiferromagnet CeRhIn5

2015 ◽  
Vol 112 (3) ◽  
pp. 673-678 ◽  
Author(s):  
Lin Jiao ◽  
Ye Chen ◽  
Yoshimitsu Kohama ◽  
David Graf ◽  
E. D. Bauer ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Fermi Surface ◽  
Quantum Phase Transitions ◽  
Continuous Phase ◽  
Multiple Quantum ◽  
Quantum Critical Points ◽  
Thermally Driven ◽  
Significant Step ◽  
Open Issues

Conventional, thermally driven continuous phase transitions are described by universal critical behavior that is independent of the specific microscopic details of a material. However, many current studies focus on materials that exhibit quantum-driven continuous phase transitions (quantum critical points, or QCPs) at absolute zero temperature. The classification of such QCPs and the question of whether they show universal behavior remain open issues. Here we report measurements of heat capacity and de Haas–van Alphen (dHvA) oscillations at low temperatures across a field-induced antiferromagnetic QCP (Bc0 ≈ 50 T) in the heavy-fermion metal CeRhIn5. A sharp, magnetic-field-induced change in Fermi surface is detected both in the dHvA effect and Hall resistivity at B0* ≈ 30 T, well inside the antiferromagnetic phase. Comparisons with band-structure calculations and properties of isostructural CeCoIn5 suggest that the Fermi-surface change at B0* is associated with a localized-to-itinerant transition of the Ce-4f electrons in CeRhIn5. Taken in conjunction with pressure experiments, our results demonstrate that at least two distinct classes of QCP are observable in CeRhIn5, a significant step toward the derivation of a universal phase diagram for QCPs.

Radical right parties and European economic integration: Evidence from the seventh European Parliament

2018 ◽  
Vol 19 (2) ◽  
pp. 321-343 ◽  
Author(s):  
Matteo Cavallaro ◽  
David Flacher ◽  
Massimo Angelo Zanetti
Keyword(s):  
European Parliament ◽  
Two Dimensions ◽  
Radical Right ◽  
Future Research ◽  
The European Union ◽  
Additive Trees ◽  
Radical Right Parties ◽  
Party Family ◽  
Clustering Criterion

This article explores the differences in radical right parties' voting behaviour on economic matters at the European Parliament. As the literature highlights the heterogeneity of these parties in relation to their economic programmes, we test whether divergences survive the elections and translate into dissimilar voting patterns. Using voting records from the seventh term of the European Parliament, we show that radical right parties do not act as a consolidated party family. We then analyse the differences between radical right parties by the means of different statistical methods (NOMINATE, Ward's clustering criterion, and additive trees) and find that these are described along two dimensions: the degree of opposition to the European Union and the classical left–right economic cleavage. We provide a classification of these parties compromising four groups: pro-welfare conditional, pro-market conditional, and rejecting. Our results indicate that radical right parties do not act as a party family at the European Parliament. This remains true regardless of the salience of the policy issues in their agendas. The article also derives streams for future research on the heterogeneity of radical right parties.

scholarly journals Detecting Topological Transitions in Two Dimensions by Hamiltonian Evolution

2017 ◽  
Vol 119 (19) ◽  
Author(s):  
Wei-Wei Zhang ◽  
Barry C. Sanders ◽  
Simon Apers ◽  
Sandeep K. Goyal ◽  
David L. Feder
Keyword(s):  
Two Dimensions ◽  
Topological Transitions ◽  
Hamiltonian Evolution

scholarly journals Lie Group Classification of a Generalized Lane-Emden Type System in Two Dimensions

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Motlatsi Molati ◽  
Chaudry Masood Khalique
Keyword(s):  
Quadratic Forms ◽  
Type System ◽  
Lie Symmetry ◽  
Two Dimensions ◽  
Group Classification ◽  
Classical Approach ◽  
Physical Sciences ◽  
Lie Group Classification ◽  
Physical Phenomena

The aim of this work is to perform a complete Lie symmetry classification of a generalized Lane-Emden type system in two dimensions which models many physical phenomena in biological and physical sciences. The classical approach of group classification is employed for classification. We show that several cases arise in classifying the arbitrary parameters, the forms of which include amongst others the power law nonlinearity, and exponential and quadratic forms.

Fermi surface renormalization in two dimensions

2004 ◽  
Vol 408-410 ◽  
pp. 254-256 ◽  
Author(s):  
H. Freire ◽  
E. Corrêa ◽  
A. Ferraz
Keyword(s):  
Fermi Surface ◽  
Two Dimensions
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