title: Attojoule calorimetry of mesoscopic superconducting loops.
abstract: We report the first experimental evidence of nontrivial thermal behavior of the simplest mesoscopic system--a superconducting loop. By measuring the specific heat C of an array of 450,000 noninteracting aluminum loops with very high accuracy of approximately 20 fJ/K, we show that the loops go through a periodic sequence of phase transitions (with a period of an integer number of magnetic flux quanta) as the magnetic flux threading each loop is increased. The transitions are well described by the Ginzburg-Landau theory and are accompanied by discontinuities of C of only several thousands of Boltzmann constants kB.
authors.affiliation: Centre de Recherches sur les Très Basses Températures, Centre National de la Recherche Scientifique, BP 166, 38042 Grenoble Cedex 09, France. Olivier.Bourgeois@grenoble.cnrs.fr
authors.forename: O
authors.initials: O
authors.lastname: Bourgeois
authors.forename: S E
authors.initials: SE
authors.lastname: Skipetrov
authors.forename: F
authors.initials: F
authors.lastname: Ong
authors.forename: J
authors.initials: J
authors.lastname: Chaussy