Specific-heat jump of superconducting lamellas with pair-breaking boundary conditions

Specific-heat measurements are reported for aluminum foils and tin films near their superconductive transition point. Surface pair-breaking effects were induced by three different means: the implantation of gadolinium impurities, the superimposition of the stray fields from iron deposits, and the proximity effect with chromium. The specific-heat jump reduction and the shift in the critical temperature are analyzed within the framework of Fulde and Moormann calculations on the thermodynamical properties of superconducting contacts. On the whole a fair agreement between experiment and theory is observed, but some limitations of the theoretical treatment and some difficulties in the experimental situation are discussed