Topology effects on the heat capacity of mesoscopic superconducting disks

Florian Ong (1) , Olivier Bourgeois (1)

1 NEEL - TPS - Thermodynamique et biophysique des petits systèmes

Phase transitions in superconducting mesoscopic disks have been studied over the $H-T$ phase diagram through heat capacity measurement of an array of independent aluminium disks. These disks exhibit non periodic modulations versus $H$ of the height of the heat capacity jump at the superconducting to normal transition. This behaviour is attributed to giant vortex states characterized by their vorticity $L$. A crossover from a bulk-like to a mesoscopic behaviour is demonstrated. $C_{\rm p}$ versus $H$ plots exhibit cascades of phase transitions as $L$ increases or decreases by one unity, with a strong hysteresis. Phase diagrams of giant vortex states inside the superconducting region are drawn in the vortex penetration and expulsion regimes and phase transitions driven by temperature between vortex states are thus predicted in the zero field cooled regime before being experimentally evidenced.

Mots clés: mesoscopic and nanoscale systems; thermodynamic properties; superconductivity phase diagrams; nanophysics; nanocalorimetry

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

Florian Ong, Olivier Bourgeois. Topology effects on the heat capacity of mesoscopic superconducting disks. EPL - Europhysics Letters, 2007, 79 (6), pp.67003. ⟨10.1209/0295-5075/79/67003⟩. ⟨hal-00167716⟩