Paramagnetic breakdown of superconductivity in nanoscale particles at finite temperature

N. CANOSA ; R. ROSSIGNOLI

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

APS

Lugar: New York; Año: 2000 vol. 62 p. 5886 - 5891

0163-1829

The effects of temperature and fluctuations on the paramagnetic breakdown of superconductivity in nanometer-scale systems are investigated using the static path plus random phase approximation to the partition function, implemented with number parity projection. The dependence with size and parity of the BCS critical fields is examined, but as size diminishes the ensuing transitions become strongly attenuated by gap fluctuations, which lead to non-negligible pairing effects in the magnetization and the odd-even free energy difference beyond the critical fields. The stepwise decrease of pairing correlations with increasing fields is also discussed. Comparison with exact results for a very small system confirms the predictions of the present method.