CRITICAL FIELD IN SPIN GLASSES : A SCALING ANALYSIS

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-1071-C8-1072
Author(s):  
M. A. Continentino ◽  
E. Szkatulla ◽  
B. Elschner ◽  
H. Maletta
Keyword(s):  
Critical Field ◽  
Spin Glasses ◽  
Scaling Analysis

scholarly journals Upper critical field and superconductor-metal transition in ultrathin niobium films

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Iryna Zaytseva ◽  
Aleksander Abaloszew ◽  
Bruno C. Camargo ◽  
Yevgen Syryanyy ◽  
Marta Z. Cieplak
Keyword(s):  
Critical Field ◽  
Upper Critical Field ◽  
Scaling Analysis ◽  
Cooper Pairs ◽  
Amorphous Films ◽  
Scaling Exponents ◽  
Negative Contribution ◽  
First Case ◽  
20 Nm ◽  
The Magnetic Field

Abstract Recent studies suggest that in disordered ultrathin films superconducting (SC) state may be intrinsically inhomogeneous. Here we investigate the nature of SC state in ultrathin Nb films, of thickness d ranging from 1.2 to 20 nm, which undergo a transition from amorphous to polycrystalline structure at the thickness $$d \simeq 3.3$$ d ≃ 3.3  nm. We show that the properties of SC state are very different in polycrystalline and amorphous films. The upper critical field ($$H_{c2}$$ H c 2 ) is orbitally limited in the first case, and paramagnetically limited in the latter. The magnetic field induced superconductor-metal transition is observed, with the critical field approximately constant or decreasing as a power-law with the film conductance in polycrystalline or amorphous films, respectively. The scaling analysis indicates distinct scaling exponents in these two types of films. Negative contribution of the SC fluctuations to conductivity exists above $$H_{c2}$$ H c 2 , particularly pronounced in amorphous films, signaling the presence of fluctuating Cooper pairs. These observations suggest the development of local inhomogeneities in the amorphous films, in the form of proximity-coupled SC islands. An usual evolution of SC correlations on cooling is observed in amorphous films, likely related to the effect of quantum fluctuations on the proximity-induced phase coherence.

PHASE TRANSITIONS IN SPIN GLASSES

2009 ◽  
Vol 20 (09) ◽  
pp. 1411-1421
Author(s):  
A. P. YOUNG
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Spin Glass ◽  
Spin Glasses ◽  
Finite Size ◽  
Three Dimensions ◽  
Scaling Analysis ◽  
Zero Field ◽  
Exchange Method ◽  
Ising Spin

Some recent progress in Monte Carlo simulations of spin glasses will be presented. The problem of slow dynamics at low temperatures is partially alleviated by use of the parallel tempering (replica exchange) method. A useful technique to check for equilibration (applicable only for a Gaussian distribution) will be discussed. It will be argued that a finite size scaling analysis of the scaled correlation length of the system is a good approach with which to investigate phase transitions in spin glasses. This method will be used to study two questions: (i) whether there is a phase transition in zero field in the Heisenberg spin glass in three dimensions, and (ii) whether there is phase transition in a magnetic field in an Ising spin glass, also in three dimensions.

Magnetic resonance in EuxSr1?xS: evidence for a critical field in spin glasses

1988 ◽  
Vol 72 (4) ◽  
pp. 471-475 ◽  
Author(s):  
M. A. Continentino ◽  
E. Skatulla ◽  
B. Elschner ◽  
H. Maletta
Keyword(s):  
Magnetic Resonance ◽  
Critical Field ◽  
Spin Glasses

RECENT DEVELOPMENTS IN ISING SPIN GLASSES

1996 ◽  
Vol 07 (03) ◽  
pp. 327-335 ◽  
Author(s):  
A. P. YOUNG ◽  
N. KAWASHIMA
Keyword(s):  
Transition Temperature ◽  
Spin Glasses ◽  
Three Dimensional ◽  
Finite Size ◽  
Scaling Analysis ◽  
Finite Size Scaling ◽  
Size Scaling ◽  
Ising Spin ◽  
Recent Developments ◽  
Rule Out

We have studied the three-dimensional Ising spin glass with a ± J distribution by Monte Carlo simulations. Using larger sizes and much better statistics than in earlier work, a finite size scaling analysis shows quite strong evidence for a finite transition temperature, Tc, with ordering below Tc. Our estimate of the transition temperature is rather lower than in earlier work, and the value of the correlation length exponent, ν, is somewhat higher. Because there may be (unknown) corrections to finite size scaling, we do not completely rule out the possibility that Tc = 0 or that Tc is finite but with no order below Tc. However, from our data, these possibilities seem less likely.

scholarly journals Finite-size scaling analysis of the distributions of pseudo-critical temperatures in spin glasses

2011 ◽  
Vol 2011 (10) ◽  
pp. P10019 ◽  
Author(s):  
A Billoire ◽  
L A Fernandez ◽  
A Maiorano ◽  
E Marinari ◽  
V Martin-Mayor ◽  
...  
Keyword(s):  
Spin Glasses ◽  
Finite Size ◽  
Scaling Analysis ◽  
Finite Size Scaling ◽  
Critical Temperatures ◽  
Size Scaling
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