Interplay of Anisotropy and Disorder in the Doping-Dependent Melting and Glass Transitions of Vortices inBi2Sr2CaCu2O8+δ
Physical Review Letters
We study the oxygen doping dependence of the equilibrium first-order melting and second-order glass transitions of vortices in Bi_2Sr_2CaCu_2O_8+δ. Doping affects both anisotropy and disorder. Anisotropy scaling is shown to collapse the melting lines only where thermal fluctuations are dominant. Yet, in the region where disorder breaks that scaling, the glass lines are still collapsed. A quantitative fit to melting and replica symmetry breaking lines of a 2D Ginzburg-Landau model further
... that disorder amplitude weakens with doping, but to a lesser degree than thermal fluctuations, enhancing the relative role of disorder.