Critical behavior of YBa₂Cu₃O_(7-δ) and Bi₂Sr₂CaCu₂O_(8+δ) from the dual Ginzburg-Landau model

An unifying scenario for the critical behavior of YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ (YBCO) and Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ (BSCCO) is proposed. It is shown that both critical crossovers observed in these materials follow by considering two different scalings in the dual Ginzburg-Landau model. The first scaling leads to the critical exponents $\nu\approx 2/3$, $\nu'\approx 1/3$ and $\alpha\approx 0$, with $\nu$ and $\alpha$ being respectively the correlation lenght and specific heat exponents while $\nu'$ is the magnetic field penetration depth exponent. These values for the critical exponents agree with the ones obtained experimentally for YBCO single crystals. For the second scaling we obtain $\nu=1$ and $\alpha=-1$ which must be compared with the measured values $\nu\approx 1$ and $\alpha\approx-0.7$ for BSCCO. For the penetration depth exponent it is predicted the value $\nu'=1$.