O papel da pressão química sobre as flutuações termodinâmicas na magnetização diamagnética do YBa2Cu3O7-δ: abordado segundo o formalismo LLL

Abstract

In this work we investigated the role of chemical pressure on the thermodynamic fluctuation of the YBa2-xSrxCu3O7-δ (x = 0; 0,02; 0,10; 0,25 e 0,37) single crystals diamagnetic magnetization. The chemical pressure is introduced to the YBa2Cu3O7-δ structure through lattice distortion promoted by the Ba partial substitution for Sr. The single crystals structure, which were grown by self-flux method, was characterized by the X ray and polarized light microscopy techniques. The DC magnetization measurements were made with a SQUID magnetometer to H ≤ 50kOe applied parallel to the c axis and to the ab plane of the single crystals. The role of the chemical pressure on the thermodynamic fluctuation of the diamagnetic magnetization of our samples was analyzed through lowest Landau level (LLL) formalism. The application of this formalism shows that the single crystals reversible DC magnetization behavior is understood by means of 3D-LLL scale function when H ≥ 10kOe are applied parallel to the c axis and to the plane of the single crystals. In this way, we could suggest that the chemical pressure, take into account its applied amount, maintains the threedimensional character of the thermodynamic fluctuation YBa2Cu3O7-δ diamagnetic magnetization, making their character stronger due to the superconductor block compaction produced by the Ba partial substitution for Sr at YBa2-xSrxCu3O7-δ structure.