Os efeitos da desordem química na energia cinética de condensação dos pares de cooper no supercondutor YBa2Cu3O7-d1

Abstract

This work has the aim of execute an DC magnetization experimental study about chemical disorder effects on the kinetic energy density, 𝐾𝑆 𝑇,𝐵 , of Cooper pairs of the 𝑌𝐵𝑎2𝐶𝑢3𝑂7−𝛿 superconductor in the light of superconductivity virial theorem (SVT). The 𝑌1−𝑥𝐶𝑎𝑥𝐵𝑎2𝐶𝑢3𝑂7−𝛿 𝑥=0,0,01 𝑒 0,005 e 𝑌𝐵𝑎1,75𝑆𝑟0,25𝐶𝑢3𝑂7−𝛿 ceramic and single crystals samples were prepared and its equilibrium DC magnetization was recorded to 𝜇0𝐻≤5 𝑇. The kinetic energy density was colleted by the application of the 𝐾𝑆 𝑇,𝐵 =−𝑀.𝐵. The partial substitution of the Y for Ca and Ba for Sr produces a lower transition temperature value and introduces a inhomogeneous character to the samples flux dynamic. The 𝐾𝑆 𝑇,𝐵 =−𝑀.𝐵 behavior as a temperature function is characterized by a maxim intensity value to 𝑇<𝑇𝐶 that decreases as 𝑇→𝑇𝐶 until become zero at 𝑇=𝑇𝐶. The magnetic field application increases the 𝐾𝑆 T,𝐵 intensity. The Ca and Sr chemical doping lowers the 𝐾𝑆 𝑇,𝐵 intensity as compare to the pure sample. When 𝜇0𝐻≥2,5 𝑇 are applied the 𝐾𝑆 𝑇,𝐵 behavior is successively described by Abrikosov’s approach to the SVT. By another hand when 𝜇0𝐻≤2,5 𝑇 are applied the 𝐾𝑆 𝑇,𝐵 behavior is successful described by London’s approach to the SVT. The application of the London’s approach to the 𝐾𝑆 𝑇,𝐵 understanding permitted to obtain a estimation of the penetration deep, the upper critical field and the G-L effective parameter values. The critical analysis of the last data indicates that an additional contribution to the superconductor condensate kinetic energy density originated from the granular character of the samples must be considerate.