Interplay between the glassy transition and granular superconductivity in organic materials
Abstract
It is known that some (BEDT-TTF)2X layered organic superconductors undergo a glassy transition near 80 K. Our purpose is to exploit quenched disorder to obtain insights on both the superconducting state (T⩽12K) and the glassy transition by studying the superconducting properties as functions of annealing time (ta) and temperature (Ta) around 80 K. The main results on the fully deuterated κ-(BEDT-TTF)2Cu[N(CN)2]Br compound are as follows: (i) The data can be described by a percolation cluster model. (ii) At short time scales, the clusters grow with ta following a power law. (iii) At large time scales the clusters grow toward a thermodynamic state following a stretched exponential law ∝{1-exp[-(t/τ)β]} with β varying from about 0.5 to 1 in our Ta range (65-110 K). (iv) The relaxation time follows an Arrhenius law τ(T)=τ0exp(U/T) with U≈2660K and 1/τ0≈2×1013s-1 . (v) The asymptotic magnetization fits with a scaling law ∝(Ta-Tg)-n with Tg≈55K and n≈3.2 . The results are consistent with a Ising spin-glass-like model.
- Publication:
-
Physical Review B
- Pub Date:
- January 2006
- DOI:
- 10.1103/PhysRevB.73.014525
- arXiv:
- arXiv:cond-mat/0512402
- Bibcode:
- 2006PhRvB..73a4525S
- Keywords:
-
- 74.70.Kn;
- 64.60.Ak;
- 74.25.Ha;
- 74.81.Bd;
- Organic superconductors;
- Renormalization-group fractal and percolation studies of phase transitions;
- Magnetic properties;
- Granular melt-textured amorphous and composite superconductors;
- Condensed Matter - Superconductivity
- E-Print:
- 17 pages