Entropy jump at the first-order vortex phase transition in Bi2Sr2CaCu2O8+d with columnar defects

G. RUMI; L. ALBORNOZ; P.PEDRAZZINI; M. I. DOLZ; H. PASTORIZA; C. J. VAN DER BEEK; M. KONCZYKOWSKI; Y. FASANO

Materials Today: Proceedings

Elsevier

Año: 2019 vol. 14 p. 30 - 33

2214-7853

We study the entropy jump entailed in the first-order vortex melting transition (FOT) in Bi 2 Sr 2 CaCu 2 O 8+ samples by means of Hallprobe magnetometry. The samples present a diluted distribution of columnar defects (CD) introduced by irradiation with Xe ions. TheFOT is detected in ac transmittivity measurements as a paramagnetic peak whose height is proportional to the enthalpy differenceentailed in the transition. By applying the Clausius-Clapeyron relation, we quantify the evolution of the entropy jump s as a function ofthe FOT temperature, T FOT , in samples with CD and compare with data obtained in several pristine samples. On increasing the density ofCD, s is monotonically depleted with respect to the evolution found in pristine samples. The s versus T FOT dependence in the case ofpristine samples follows reasonably well the theoretical prediction of dominant electromagnetic coupling for a model neglecting theeffect of disorder. For samples with a diluted distribution of CD the data do not properly follow such a theoretical model.