AC elastocaloric effect as a probe for thermodynamic signatures of continuous phase transitions

AbstractDrylands are ecosystems with limited water resources, often subjected to desertification. Conservation and restoration efforts towards these ecosystems depend on the interplay between ecological functioning and spatial patterns formed by local vegetation. Despite recent advances on the subject, an adequate description of phase transitions between the various vegetated phases remains an open issue. Here, we gather vegetation data of drylands from Southern Spain using satellite images. Our findings support three vegetated phases, separated by two distinct phase transitions, including a continuous phase transition, with new relations between scaling exponents of ecological variables. The phase diagram is obtained without a priori assumption about underlying ecological dynamics. We apply our analysis to a different dryland system in the Western United States and verify a compatible critical behavior, in agreement with the universality hypothesis.

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Thermodynamic signatures for topological phase transitions to Majorana and Weyl superfluids in ultracold Fermi gases

Physical Review A ◽

10.1103/physreva.87.063618 ◽

2013 ◽

Vol 87 (6) ◽

Cited By ~ 16

Author(s):

Kangjun Seo ◽

Chuanwei Zhang ◽

Sumanta Tewari

Keyword(s):

Phase Transitions ◽

Fermi Gases ◽

Topological Phase ◽

Ultracold Fermi Gases ◽

Thermodynamic Signatures ◽

Topological Phase Transitions

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Excitonic spin instabilities and continuous phase transitions in quantum Hall magnets

Solid State Communications ◽

10.1016/s0038-1098(01)00102-8 ◽

2001 ◽

Vol 119 (4-5) ◽

pp. 301-308 ◽

Cited By ~ 5

Author(s):

Vittorio Pellegrini ◽

Aron Pinczuk

Keyword(s):

Phase Transitions ◽

Quantum Hall ◽

Continuous Phase

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

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1413932112 ◽

2015 ◽

Vol 112 (3) ◽

pp. 673-678 ◽

Cited By ~ 49

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.

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Continuous phase transitions in molecules: BeF2

Physics Letters A ◽

10.1016/0375-9601(81)90956-7 ◽

1981 ◽

Vol 85 (5) ◽

pp. 271-272 ◽

Cited By ~ 2

Author(s):

M.A.F. Gomes

Keyword(s):

Phase Transitions ◽

Continuous Phase

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Green Function Calculations of Properties for the Magnetocaloric Layered Structures Based Upon FeMnAsP

SPIN ◽

10.1142/s2010324716500107 ◽

2016 ◽

Vol 06 (03) ◽

pp. 1650010

Author(s):

Osvaldo F. Schilling

Keyword(s):

Magnetic Field ◽

Phase Transitions ◽

Green Function ◽

Landau Theory ◽

Random Phase ◽

Layered Structures ◽

Continuous Phase ◽

Theoretical Treatment ◽

Entropy Variation ◽

Commercial Applications

The alternating Fe–Mn layered structures of the compounds FeMnAsxP[Formula: see text] display properties which have been demonstrated experimentally as very promising as far as commercial applications of the magnetocaloric effect are concerned. However, the theoretical literature on this and other families of magnetocaloric compounds still adopts simple molecular-field models in the description of important statistical mechanical properties like the entropy variation that accompanies applied isothermal magnetic field cycling, as well as the temperature variation following adiabatic magnetic field cycles. In the present paper, a random phase approximation Green function theoretical treatment is applied to such structures. The advantages of such approach are well known since the details of the crystal structure are easily incorporated in the model, as well as a precise description of correlations between neighbor spins can be obtained. We focus on a simple one-exchange parameter Heisenberg model, and the observed first-order phase transitions are reproduced by the introduction of a biquadratic term in the Hamiltonian whose origin is related both to the magnetoelastic coupling with the phonon spectrum in these compounds as well as with the values of spins in the Fe and Mn ions. The calculations are compared with experimental magnetocaloric data for the FeMnAsxP[Formula: see text] compounds. In particular, the magnetic field dependence for the entropy variation at the transition temperature predicted from the Landau theory of continuous phase transitions is reproduced even in the case of discontinuous transitions.

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Is Independence Necessary for a Discontinuous Phase Transition within the q-Voter Model?

Entropy ◽

10.3390/e21050521 ◽

2019 ◽

Vol 21 (5) ◽

pp. 521 ◽

Cited By ~ 7

Author(s):

Angelika Abramiuk ◽

Jakub Pawłowski ◽

Katarzyna Sznajd-Weron

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Continuous Phase ◽

Voter Model ◽

Social Response ◽

Generalized Model ◽

Independent Variables ◽

The Social ◽

Discontinuous Phase ◽

Independent Behavior

We ask a question about the possibility of a discontinuous phase transition and the related social hysteresis within the q-voter model with anticonformity. Previously, it was claimed that within the q-voter model the social hysteresis can emerge only because of an independent behavior, and for the model with anticonformity only continuous phase transitions are possible. However, this claim was derived from the model, in which the size of the influence group needed for the conformity was the same as the size of the group needed for the anticonformity. Here, we abandon this assumption on the equality of two types of social response and introduce the generalized model, in which the size of the influence group needed for the conformity q c and the size of the influence group needed for the anticonformity q a are independent variables and in general q c ≠ q a . We investigate the model on the complete graph, similarly as it was done for the original q-voter model with anticonformity, and we show that such a generalized model displays both types of phase transitions depending on parameters q c and q a .

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