scholarly journals Zero-field superconducting phase transition obscured by finite-size effects in thickYBa2Cu3O7−δfilms

2004 ◽  
Vol 69 (21) ◽  
Author(s):  
M. C. Sullivan ◽  
D. R. Strachan ◽  
T. Frederiksen ◽  
R. A. Ott ◽  
M. Lilly ◽  
...  
Keyword(s):  
Phase Transition ◽  
Size Effects ◽  
Finite Size ◽  
Superconducting Phase ◽  
Zero Field ◽  
Finite Size Effects ◽  
Superconducting Phase Transition

Influence of Finite Size Effects on the Fulde-Ferrell-Larkin-Ovchinnikov State

2017 ◽  
Vol 21 (3) ◽  
pp. 748-762 ◽  
Author(s):  
Andrzej Ptok ◽  
Dawid Crivelli
Keyword(s):  
Fermi Surface ◽  
Size Effects ◽  
Cooper Pair ◽  
Finite Size ◽  
Superconducting Phase ◽  
Cooper Pairs ◽  
Fflo State ◽  
Finite Size Effects ◽  
Infinite Systems ◽  
Nano Size

AbstractThe Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is the superconducting phase for which the Cooper pairs have a non-zero total momentum, depending on the splitting of the Fermi surface sheets for electrons with opposite spin. In infinite systems the momentum is a continuous function of the temperature. In this paper, we have shown how the finite size of the system, through the discretized geometry of the Fermi surface, affects the physical properties of the FFLO state by introducing discontinuities in the Cooper pair momentum. Our calculation in an isotropic system show that the superconducting state with two opposite Cooper pair momenta is more stable than state with one momentum also in nano-size systems, where finite size effects play a crucial role.

scholarly journals Finite-size effects in disordered λφ4 model

2016 ◽  
Vol 30 (30) ◽  
pp. 1650207 ◽  
Author(s):  
R. Acosta Diaz ◽  
N. F. Svaiter
Keyword(s):  
Phase Transition ◽  
Long Range ◽  
Power Law ◽  
Order Phase Transition ◽  
Size Effects ◽  
Finite Size ◽  
Second Order ◽  
Finite Size Effects ◽  
Power Law Decay ◽  
Second Order Phase Transition

We discuss finite-size effects in one disordered [Formula: see text] model defined in a [Formula: see text]-dimensional Euclidean space. We consider that the scalar field satisfies periodic boundary conditions in one dimension and it is coupled with a quenched random field. In order to obtain the average value of the free energy of the system, we use the replica method. We first discuss finite-size effects in the one-loop approximation in [Formula: see text] and [Formula: see text]. We show that in both cases, there is a critical length where the system develop a second-order phase transition, when the system presents long-range correlations with power-law decay. Next, we improve the above result studying the gap equation for the size-dependent squared mass, using the composite field operator method. We obtain again that the system present a second-order phase transition with long-range correlation with power-law decay.

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